bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth and Survival of African Catfish (Clarias gariepinus) Larvae Fed Decapsulated Artemia, Live Daphnia, or Commercial Starter Diet
Authors: Olurin K.B. , Oluwo A.B.
Published: February 2021

The effects of three diets (decapsulated Artemia, live Daphnia spp., and commercial starter diet) on the growth and survival of Clarias gariepinus larvae were investigated in the laboratory for seven days using a completely randomized block design. Larvae were hatched by the hypophysation technique and, immediately after resorption of the yolk sac, randomly distributed into nine tanks at a stocking rate of 180 larvae per experimental plastic tank. Triplicate groups were fed treatment diets ad libitum twice daily, in the morning and in the evening. The highest growth values were obtained in larvae fed decapsulated Artemia (p<0.05), while the survival rate was similar in fish fed decapsulated Artemia and live daphnia. It is concluded that feeds of animal origin are more suitable for first feeding of C. gariepinus larvae than inert diets.
Identification and Genotyping of Vibrio ordalii: A Comparison of Different Methods
Authors: Akayli T. , Timur G. , Albayrak G. , Aydemir B.
Published: February 2021

The phenotypical, serological, and molecular identification of Vibrio ordalii isolates recovered from diseased gilthead sea bream (Sparus aurata) in the Mediterranean area were investigated. Most isolates had similar phenotypic characteristics, but some showed small differentiation in biochemical analysis. Both slide agglutination and enzyme linked immunosorbent assay (ELISA) showed that the isolates were antigenically homogeneous and no different serotypes were detected. SDS-PAGE analysis showed that the structure of lipopolysaccharide (LPS) was heterogeneous, that outer membrane proteins (OMP) display homogeneous grouping protein banding patterns, and that the LPS profile of the isolates had different banding patterns. However, random amplified polymorphic DNA (RAPD) analysis revealed genetic variation (up to 90.4%) among isolates of the same species.
Physiological Stress Responses in Strains of the Gilthead Sea Bream (Sparus aurata)
Authors: Ron Tetsuzan Benny , Gorshkova Galina , Gorshkov Sergei
Published: February 2021

In this study we examined the physiological responses of different strains of gilthead sea bream (Sparus aurata) to chronic and acute stress factors. Blood glucose levels, hematocrit, and lactate concentrations were examined in yearlings of different strains of gilthead sea bream subjected to different stress situations. In the first experiment, fish of the Ardag and ‘ebony’ strains were kept 45 days in moderate (35-45 kg/m3) or high (70-90 kg/m3) density. There were no significant effects on the blood glucose level but, at both densities, hematocrit was significantly higher in the Ardag strain (33.2±3.0% at moderate and 44.5±1.6% at high) than in the ebony strain (22.0±3.0% and 19.9±2.7%, respectively). The interaction of ‘strain’ and ‘crowding’ was highly significant, suggesting that hematocrit may respond differently in each strain to crowding. In the second experiment, we examined the effects of acute stress (handling without anesthesia) among four strains representing Mendelian mutations that affect body coloration in gilthead sea bream: ebony, ‘white’, ‘yellow’, and the normally pigmented Ardag. Significant variations in the glucose and lactate concentrations suggest that genotypes of gilthead sea bream may have heritable differences in their physiological responses to stress factors.
Effect of Low Salinity on Yolk Sac Absorption and Alevin Wet Weight of Rainbow Trout Larvae (Oncorhynchus mykiss)
Authors: Başçınar Nadir
Published: February 2021

Growth, yolk sac absorption, and maximum wet weight of alevin rainbow trout (Oncorhynchus mykiss) stocked in fresh water (0 salinity), water with 4‰ salinity, or water with 8‰ salinity were determined. Larvae were sampled on the 329th degree-day when 50% of the eggs hatched, and on degree-days 361, 396, 432, 467, 496, 528, 557, and 584. Sampled larvae were anesthetized in benzocaine solution (20 mg/l) and preserved in 10% formaldehyde. At hatching, mean length was 14.25±0.63 mm and total wet weight was 58.16±9.98 mg. Larvae reached the swim-up stage at 96.94±8.71 mg on the 28th day in fresh water, at 120.29±9.26 mg on 19th day in 4‰ salinity, and at 102.80±5.88 mg on 22nd day in 8‰ salinity. The total length and dry weight of the larvae at the swim-up stage differed significantly among treatments (p<0.001). There was a significant relationship between larvae dry weight and degree-day. The best growth, yolk sac consumption, and alevin wet weight were obtained in 4‰ salinity.
Soybeans Heat-Treated by Different Methods in Diets for Goldfish (Carassius auratus) Fry
Authors: Vartak Vivek Rohidas , Singh Ravendra Kumar
Published: February 2021

The objective of this study was to determine the effect of diets supplemented with soybean meal processed by different heat treatments on growth, survival, and body composition of goldfish (Carassius auratus) fry. The fry (5.25±0.27 cm) were fed isonitrogenous (40%) diets containing soybean meal for 60 days. The first treatment contained soybeans toasted in a pan for 10 min. The second and third treatments contained soybeans oven- heated for 30 and 60 min, respectively. The fourth treatment contained raw soybeans. There were no significant differences (p>0.05) in survival between treatments. There was a significant increase in specific growth rate, protein efficiency ratio, and food conversion ratio with the diet containing soybeans oven-heated for 60 min. No significant differences were detected in body composition among the four treatments.
The Effects of Light Intensity and Color on Aggressive Interactions in the Dusky Kob, Argyrosomus japonicus
Authors: Timmer Rowan , Magellan Kit
Published: February 2021

The dusky kob, Argyrosomus japonicus, is highly susceptible to stress under culture conditions. Such stress frequently involves a high degree of aggression, leading to cannibalism. Here, the effects of light intensity and color on the frequency of aggressive interactions and the time that passes between presentation of food and food first being eaten (feeding latency) in this species were examined. Aggression was lowest when fish were maintained in partial shade and highest in red light. Feeding latency was not affected by light treatment. The results can aid the aquaculture industry in determining the optimal light intensity for minimizing aggressive behavior in A. japonicus.
The Effects of Different Carotenoid Sources on Skin Pigmentation of Goldfish (Carassius auratus)
Authors: Yeşilayer Nihat , Aral Orhan , Karsli Zafer , Öz Meryem , Karaçuha Ali , Yağci Feraye
Published: February 2021

The aim of this study was to investigate the effect of different carotenoid sources on goldfish (Carassius auratus) skin pigmentation. The value of goldfish depends on the intensity of the skin color. In the red variety of goldfish, an orange-red hue is desirable. Juvenile goldfish were fed one of five diets for five months to determine the effects of carotenoids on skin pigmentation, growth, feed efficiency, and survival: (1) astaxanthin (carophyll pink at 75 mg/kg), (2) canthaxanthin (carophyll red at 75 mg/kg), (3) Gammarus spp. (75 mg/kg), (4) Oleoresin paprika (180 mg/kg), and (5) an unsupplemented control. Growth and feed efficiency did not significantly differ among groups. Initial and final samples of head skin were measured by colorimetric analysis for lightness (L), redness (a), yellowness (b), hue (Hºab), and chroma (Cab). The best red color (a* and Hºab) was obtained with the astaxanthin, canthaxanthin, and paprika diets.
Effect of Feeding Frequency and One Day Fasting on Tilapia (Oreochromis niloticus) and Water Quality
Authors: Villarroel Morris , Alavriño José Mario R. , López-Luna Javier
Published: February 2021

The aim of this study was to investigate the effects of different feeding frequencies and one day fasting on the quality of tank water in a recirculation system and on the growth, body composition, and welfare of juvenile Nile tilapia (Oreochromis niloticus). One hundred and twenty juveniles (24±4.2 g) were fed two or four times a day, with or without a one-day fast every fourth day. Fish that were fed two or four times every day grew more than fish that fasted once a week, but there were no significant differences in food conversion rate or specific growth rate among the four treatments. Regarding body composition, fish fed four times a day, whether fasted or not, had a higher percentage of fat, while the percentage of protein was highest in fish fed four times a day with a one-day fast every fourth day. Plasma cortisol levels at the end of the trial were similar between frequencies, suggesting little effect of feeding frequency on stress level. Electrical conductivity in tank water was highest in the twice a day/fasting group and related to higher sodium (Na+) and chloride (Cl-) levels. Overall, results suggest that fasting one day a week does not affect growth efficiency and that tilapia adjust well to relative changes in feeding frequency.
Effect of Lipopolysaccharide (LPS) and Outer Membrane Protein (OMP) Vaccines on Protection of Grass Carp (Ctenopharyngodon idella) against Aeromonas hydrophila
Authors: Sun Jinhui , Wang Qingkui , Qiao Zhiyi , Bai Dong-qing , Sun Jingfeng , Qiao Xiuting
Published: February 2021

The gram-negative bacterium, Aeromonas hydrophila, causes high mortality and economic losses to the aquaculture industry. We investigated whether lipopolysaccharide (LPS) or outer membrane proteins (OMP) from A. hydrophila can enhance specific and/or non-specific immunity in grass carp (Ctenopharyngodon idella). Fish were injected intraperitoneally with LPS, OMP, or formalin-killed cells (FKC) from A. hydrophila. The control group was injected with phosphate buffered saline (PBS). All three antigens elicited strong immune responses. Respiratory burst and phagocytic activities in head kidney leukocytes and serum lysozyme activity peaked on day 21 after vaccination. Heavy chain gene transcription of immunoglobulin M and Z in the head kidney in vaccinated fish peaked on day 28. Relative percent survival was 83.3%, 72.2%, and 55.6% in the LPS, OMP, and FKC groups, respectively, but only 10% in control fish. Results suggest that LPS and OMP isolated from A. hydrophila can enhance specific immunity, non-specific immunity, and protection against A. hydrophila in fish. Thus, LPS and OMP could be important antigens for development of vaccines to control diseases caused by A. hydrophila in grass carp and other aquatic animals.
Effects of Dietary Fish Oil Substitution with Palm Oil on Growth, Survival, and Muscle Proximate Composition of Cirrhinus mrigala (Hamilton, 1822)
Authors: Singh Soibam Khogen , Rather Mohd Ashraf , Mandal Sagar C. , Das Pronob , Pawar Nilesh , Singh Y. Jackie , Dar Shabir Ahmad
Published: February 2021

A 60-day growth experiment was carried out to evaluate the effect of replacing dietary cod liver oil with palm oil on the growth, survival, and muscle proximate composition of the Indian major carp, Cirrhinus mrigala. Five diets were fed to triplicate groups of 20 advanced C. mrigala fry (2.16±0.01 g): 100% cod liver+0% palm (control), 25% palm+75% cod liver, 50% palm+50% cod liver, 75% palm+25% cod liver, and 100% palm+0% cod liver. At the end of the experiment, mean weight gain, average daily growth, specific growth rate, feed conversion efficiency, feed conversion ratio, and percentage survival were assessed. Growth performance and survival were not compromised when fish oil was substituted with palm oil up to 25%. However, beyond this level, growth was significantly retarded (p<0.01). There were no significant (p>0.01) differences in feed efficiency or muscle proximate composition. Results confirm the feasibility of substituting up to 25% dietary fish oil by palm oil in diets for C. mrigala advanced fry without negatively affecting growth or feed utilization efficiency.
Effect of Stocking Density on Growth and Survival of Sub-Adult Tench (Tinca tinca Linnaeus 1758)
Authors: Pantazis Panagiotis A.
Published: February 2021

Three hundred and fifty-nine (359) sub-adult tench were allocated to twelve tanks to investigate the effect of stocking density on survival and growth. The experimental population consisted of two weight groups (small = 11.27-11.36 g and large = 15.38-15.44 g) and two initial stocking densities (1.4 kg/m3 and 2.5 kg/m3). The experiment lasted seven months (217 days). The total lack of deformities in the caudal peduncle in all groups and the low incidence of mortality indicate that sub-adult tench cultured in a water recirculation system perform well when stocked at a relatively high stocking density (2.5 kg/m3) and fed 1.0% of their body weight per day. By the end of the experiment, the weight of the best-performing groups increased 83-90% and confirmed the hypothesis that high densities favor the growth and survival of sub-adult tench reared in artificial tanks in a water recirculation system.
Pigmentary and Zootechnical Responses of Juvenile Litopenaeus vannamei (Boone, 1931) Maintained on Diets Supplemented with Xanthophylls of Marigold Tagetes erecta Flowers
Authors: Piña-Valdéz Pablo , Aguirre-Hinojosa Eduardo , Garza-Aguirre María del Carmen , Montoya-Olvera Ricardo , Torres-Quiroga José Odón , Nieves-Soto Mario
Published: February 2021

Practical diets supplemented with 75 or 150 ppm xanthophylls (75% zeaxanthin, 15% lutein) industrially extracted from marigold (Tagetes erecta L.) flowers increased the astaxanthin and total carotenoid concentrations in juvenile Litopenaeus vannamei, compared to shrimp fed a practical control diet. Our results paralleled or exceeded those obtained with a diet containing 75 ppm supplementary synthetic astaxanthin. The post-feeding astaxanthin concentration accounted for more than 84% of the total carotenoid concentration in shrimp fed either diet, while beta-carotene, zeaxanthin, lutein, and other non-identifiable carotenoids comprised a minority of the total concentration. That this was seen in both the tail exoskeleton and abdominal muscle indicates that L. vannamei can metabolize precursor xanthophylls to produce astaxanthin. In most cases, more than 60% of the astaxanthin was esterified. In general, survival improved in shrimps fed the supplemented diets compared to those fed the control diet. There were no differences in growth.
Effects of Dietary Pyridoxine on Growth and Physiological Responses of Labeo rohita Fingerlings Reared in High Water Temperature
Authors: Akhtar M.S. , Pal A.K. , Sahu N.P. , Ciji Alexander , Meena D.K.
Published: February 2021

The role of dietary pyridoxine (vitamin B6) on the growth and physiological responses of Labeo rohita fingerlings reared in a high temperature of 33°C was examined in a 60-day trial. Two hundred and seventy fingerlings (6.71±0.32 g) were randomly distributed into six treatments in triplicate. Five iso-caloric and iso-nitrogenous purified diets were prepared with graded levels of pyridoxine: 0, 10, 50, 100, and 200 mg. The control group was given a diet containing 10 mg pyridoxine and reared at ambient temperature (26°C). Pyridoxine supplementation at 100 or 200 mg/kg diet significantly augmented the specific growth rate but there were no significant (p>0.05) effects of pyridoxine supplementation on the feed conversion ratio. Superoxide-dismutase, catalase, blood glucose, and serum cortisol were significantly lower and acetylcholinesterase (AchE) significantly (p<0.05) higher in the pyridoxine-fed groups. Results indicate that dietary pyridoxine supplementation at the rate of 100 mg/kg diet augments growth and helps lower stress in L. rohita fingerlings reared in a high water temperature.
Detection of Acylated Homoserine Lactone (AHL) in the Heterotrophic Bacteria Z-TG01 and Its Ecological Action on the Algae, Chlorella vulgaris
Authors: Tang Xuexi , Bi Xiangdong , Xing Kezhi , Zhou Wenli
Published: February 2021

Heterotrophic bacteria Z-TG01 was isolated from the phycosphere of Chlorella vulgaris and identified as Sphingomonas paucimobilis by VITEK 2 Compact automated system with an excellent confidence level (99.0% probability). We detected acylated homoserine lactones (AHL) bioactivity in the growth process of Z-TG01 using Agrobacterium tumefaciens KYC55. The effects of C. vulgaris on AHL bioactivity, as well as the mutual influence of C. vulgaris and Z-TG01 in a co-culture system, were investigated. Results showed that AHL bioactivity of bacteria Z-TG01 varied with the bacteria density and was inhibited by supernatants of C. vulgaris culture in the early and middle exponential phases within 2 h (p<0.01), and in the late exponential phase within 1.5 h (p<0.05 or p<0.01). Within a certain cell density, bacteria Z-TG01 and C. vulgaris promote mutual growth in a co-culture system.
Ultrastructure of Erythrophores and Xanthophores of the Siamese Fighting Fish, Betta splendens
Authors: Khoo Gideon , Lim Tit Meng , Phang Violet P.E.
Published: February 2021

The ultrastructural morphology of brightly colored pigment cells (chromatophores) of Siamese fighting fish, Betta splendens, was investigated by transmission electron microscopy. The major pigment cells in the epidermis and dermis of the red and golden strains were erythrophores and xanthophores, respectively. Specific combinations of these chromatophores formed the basis of pigmentation patterns in both strains. The ultrastructure of the erythrophores was characterized by ellipsoidal electron-lucent vesicles that had limiting membranes and inner lamellae. The latter appeared whorl-like due to a concentric arrangement of parallel membranes. The xanthophores contained small and large cytoplasmic vesicles that appeared hollow and electron-lucent, with some vesicles displaying slightly electron dense particles. Sections of some large vesicles also revealed a very thin membrane enveloping these droplet-like vesicles.
Effect of Astacin on Growth and Color Formation of Juvenile Red-White Ornamental Carp (Cyprinus carpio var. koi L)
Authors: Liang Yong-jun , Bai Dong-qing , Yang Guang , Wei Dong , Guo Mei , Yan Shan-shan , Wu Xuan , Ning Bo
Published: February 2021

Body color is an important quality and determines the value of koi. Fish are unable to fully synthesize carotenoid pigments. Therefore, carotenoid needs to be added to their diets. This study determined the effect of astacin on the growth and body color enhancement in healthy red-white ornamental carp (Cyprinus carpio var. koi). Fish were fed diets containing 0 (control), 50, 100, 150, 200, or 250 mg astacin/kg diet for 8 weeks. At the end of the experiment, samples of red-white, red, and white skin, head, scales, and fin ray were collected for carotenoid content analysis and visual observation. Fish weight and specific growth rate were significantly higher in fish fed the 150, 200, and 250 mg diets than in fish fed the control while the feed conversion rates in the 200 and 250 groups were significantly lower than in the control. Carotenoid deposition in the skin, head, scale, and fin ray of fish fed diets containing astacin was significantly higher than that those fed the control. In addition, a higher astacin content resulted in a brighter body color. The highest carotenoid concentration was achieved when 250 mg astacin/kg feed was added. Astacin was mainly deposited in the skin, scales, and head.
Influence of Temperature and Parasite Intensity on Egg Production and Hatching of the Monogenean Dactylogyrus extensus
Authors: Turgut Emine
Published: February 2021

Dactylogyrus extensus is a species of monogenetic flukes of the family Dactylogyridae that infests cultured as well as wild fish. Understanding its reproductive biology would help control its population. Temperature and parasite intensity influence egg production and larvae hatching. Therefore, we investigated the effect of these parameters on egg production in vivo and in vitro of D. extensus taken from the gills of Cyprinus carpio at 10°C and 17°C, and on larvae hatching at 10°C, 17°C, and 25°C. Temperature significantly effected both egg production and larvae hatching. A significantly greater number of eggs was produced at 17°C than at 10°C, but the hatching rate was higher and more rapid at 25°C. Egg production in vitro was relatively higher than in vivo. Eggs were resistant to cold water and larvae development was inhibited at 2-3°C. However, when the temperature was increased, larvae development commenced and hatching was observed.
Breeding of Climbing Perch (Anabas testudineus Bloch, 1792) Induced with Ovatide
Authors: Singh Yumnam Bedajit , Saha Himadri , Mandal Babita , Tandel Ritesh
Published: February 2021

Climbing perch (Anabas testudineus) is a much demanded fish in the northeastern part of India, yet the absence of a standardized method to induce breeding remains a major constraint in the development of aquaculture of this species. In this study, breeding was induced using 0.1, 0.2, or 0.3 ml/kg body weight of the synthetic hormone Ovatide and compared with fish injected with 30 mg carp pituitary extract (CPE) per kg body weight or 0.5 ml saline (control). Male and female brooders were injected once with an identical dose and left to spawn in tubs at a ratio of 2:1. No breeding occurred in the saline-injected control fish. There was partial spawning in the 0.1 and 0.2 Ovatide treatments and complete spawning in fish injected with 0.3 Ovatide. Spawning and number of eggs in fish injected with 0.3 Ovatide did not statistically differ from results in fish injected with CPE (p≥0.05). The present experiment suggests that Ovatide at 0.3 ml/kg body weight is optimal for seed production of climbing perch held in captivity and can be used for species restoration.
Effect of Total Dissolved Solids and Temperature on Bacteriophage Therapy against Luminous vibriosis in Shrimp
Authors: Karunasagar Indrani , Venugopal Moleyur Nagarajappa , Maiti Biswajit , Choudhury Tanmoy Gon
Published: February 2021

Bacteriophage therapy is an efficient, eco-friendly, and scientifically demonstrable solution to antibiotic resistance in bacteria. Environmental factors have a profound influence on the growth and activity of phages. We evaluated the influence of two important parameters of the aquatic environment on phage activity, i.e., total dissolved solids (TDS) and temperature. Evaluated levels of TDS were 11.25, 22.63, and 38.43 mg/ml; studied temperatures were 20, 30, and 37ºC. Levels were chosen from the ranges of values encountered during larvae rearing in a hatchery. Of seven
Partial Purification and Characterization of Amylases from the Digestive Tract of the Indian Medium Carp Labeo fimbriatus (Bloch, 1797)
Authors: Kushwaha J.P. , Sridhar N. , Kumar U.V. , Prasanth K.P.H. , Raghunath M.R. , Eknath A.E.
Published: February 2021

Partial purification of amylases from the digestive tract of the Indian medium carp Labeo fimbriatus through acetone fractionation and Sephadex G-75 gel filtration resulted in 5-fold purification with 29% recovery. Characterization of amylase activity revealed two pH optima at 4.5 and 6.5-7.0. Activity was stable over a wide pH range of 4.0-10.0. Optimum incubation temperature was 25°C. The enzyme lost 80% activity at 50°C within 30 min and was inhibited by 1 mM p-chloromercuri benzoate, ethylene diamine tetra-acetate, and phenyl methyl sulphonyl fluoride. The heavy metal ions Hg++, Cd++, Cu++, Zn++, Fe++, Pb++, Bi++, and Ag+ strongly inhibited enzyme activity whereas Ca++ activated it. Native polyacrylamide gel electrophoresis of the purified amylase fractions revealed four bands, with corresponding molecular weights of 72, 68, 66, and 65 kDa. Amylase activity from L. fimbriatus exhibited linear hydrolysis of starch up to 7% concentration.
A Loop-Mediated Isothermal Amplification Method Targeting the fbsB Gene for Rapid Detection of Streptococcus agalactiae, the Causative Agent of Streptococcosis in Farmed Fish
Authors: Wang B. , Cai S.H. , Lu Y.S. , Zhang X.L. , Huang Y.C. , Jian J.C. , Wu Z.H.
Published: February 2021

The purpose of this study was to develop a loop-mediated isothermal amplification (LAMP) method for rapid, sensitive, and simple detection of Streptococcus agalactiae in farmed fish. A set of four primers, two outer and two inner, was designed from the fibrinogen-binding (fbsB) proteins gene sequence of S. agalactiae, and conditions for LAMP were optimized as incubation of all reagents for 60 min at 64°C. LAMP products were judged by agar gel electrophoresis as well as the naked eye after development by Synergy Brands Green I (SYBR Green I). Sensitivity of the assay was 2.8 × 103 CFU/ml (2.8 CFU per reaction) and no positive amplification was detected for other related bacteria. This LAMP method can be used to detect S. agalactiae infection in the laboratory and the field.
Efficiency of Shelters in Reducing Cannibalism among Juveniles of the Marine Blue Swimmer Crab, Portunus pelagicus
Authors: Ravi R. , Manisseri M.K.
Published: February 2021

Portunus pelagicus is an important crab species for aquaculture in India. Cannibalism during the megalopa and juvenile stages is a major constraint in standardizing the hatchery technology of this species. The present study evaluates the efficiency of various types of shelters in curbing cannibalism in juvenile P. pelagicus. Larvae from eggs of berried females collected from the wild were reared to first crab instars under controlled conditions. They were stocked in 200-l tanks at a density of 10/l with shelters of different materials: (a) nylon mesh netting, (b) seagrass, (c) seagrass and sand, and (d) without any material as shelter. At the end of the experimental period (15 days), the mean survival rates of the juveniles in each treatment were subjected to one-way ANOVA and pairs that significantly differed (p<0.01) were traced using Fisher’s LSD. The seagrass and sand treatment produced the highest mean survival (88±3%); the lowest (24.67±2.52%) was obtained in the treatment where no material was provided as a shelter.
Visualization of Sparus macrocephalus Infection by GFP-Labeled Edwardsiella tarda
Authors: Yan Maocang , Wang Xuepeng , Hu Weili , Chen Shaobo , Zhang Saile , Xie Qilang
Published: February 2021

Edwardsiella tarda is a fish pathogen that causes systemic infections in many marine and freshwater fish. The invasion pathway of E. tarda was studied in vivo in Sparus macrocephalus using a virulent strain of E. tarda, transformed with a plasmid encoding green fluorescent protein and sharing similar virulence characteristics as the parent strain. Fish were divided into six groups: (A) bacteria bath-challenged, unwounded fish, (B) bacteria bath-challenged fish, skin mucus layer partially removed by paper towel, (C) bacteria bath-challenged fish, skin artificially wounded by scalpel, (D) bacteria intramuscularly-challenged fish, (E) normal fish, and (F) phosphate-buffered saline intramuscularly-treated fish. The number of bacteria from blood, gills, kidney, muscle, spleen, liver, and intestine were determined 2, 4, 6, 12, 24, and 48 h post-challenge. High numbers of bacteria were observed in the gills and intestine, followed by the liver, kidney, spleen, and muscle of infected fish. The number of bacteria was significantly higher in groups B and C than in group A. The skin, intestine, and gills were likely the main routes of entry for E. tarda.
Effect of Temperatures and Storage Periods on Fertilizing and Hatching of Short-Term Preserved Scaly Carp (Cyprinus carpio) Eggs
Authors: Bozkurt Yusuf , Yavas Ilker
Published: February 2021

Preserved fish eggs can be used in many applications including artificial propagation and genetic studies. The aim of this study was to determine the effects of different temperatures and storage periods on fertilization and hatching success of short-term preserved scaly carp (Cyprinus carpio) eggs. Eggs were kept in 4 ml ovarian fluid in 10-cm petri dishes that were stored in a refrigerator at 4°C, 8°C, or 12ºC for 30, 60, or 90 min. The stored eggs were fertilized by adding 200 µl milt to each petri dish. The highest fertilization (98%) and hatching (80%) rates were obtained with eggs stored for 30 min at 8ºC and 12ºC respectively, indicating that this combination was best for short-term preservation of scaly carp eggs.
Effect of Total Fish Meal Replacement with Vegetal Protein Alone or Combined with Rendered Animal Protein on Growth Performance and Tissue Composition of European Catfish (Silurus glanis L.)
Authors: Havasi Máté , Kumar Shivendra , Nagy Zoltán , Pál László , Beliczky Gábor , Bercsényi Miklós , Gál Dénes
Published: February 2021

A feeding trial was conducted for six weeks to determine the effect of the replacement of fishmeal (FM) either with vegetal protein (mainly soybean) and rendered animal protein combined or vegetal protein alone on growth and carcass composition of European catfish, Silurus glanis. One hundred and thirty five fish (average weight 70.90±5.10g ±SD) were randomly distributed into three treatments in triplicate. Fish were fed with either of three isonitrogenous (35% crude protein) and isocaloric (16.70 MJ/kg DE) experimental diets. The diets were: fish meal (FM) based diet, fish meal protein replaced with a combination of vegetal protein and rendered animal protein (AP), and fish meal replaced with vegetal protein only (SM). Weight gain (%), specific growth rate, protein efficiency ratio, and apparent net protein utilization of FM diet fed groups were similar (P>0.05) with AP diet fed group being significantly higher (P < 0.05) than the SM group. Feed conversion ratio with FM diet was similar (P < 0.05) to that of the AP diet, and significantly lower than SM diet. The present experiment indicated that vegetal protein alone cannot replace total FM protein in the diet of Silurus glanis, however, vegetal protein and rendered animal protein combined, can replace total fish meal protein, with no detrimental effect on growth performance, feed utilization, and body composition.
Isolation, Identification, and Detection, of the Virulence Factor of Vibrio cholerae in Grass Carp
Authors: Teng Tao , Liang Liguo , Xie Jun
Published: February 2021

In this study, we examined the mass mortality of grass carp (Ctenopharyngodon idellus) caused by Vibrio cholerae in Jiangsu Province. We evaluated the phenotypic, morphological, physiological, biochemical, and virulence factor characteristics as well as the drug sensitivity of the CY-1 strain isolated from the liver, spleen, and kidney, of dying grass carp. The 16S rRNA gene (GenBank accession number: KF386612) was amplified and compared with sequences deposited in GenBank. A phylogenetic tree analysis showed that the isolated pathogen was V. cholerae and that it was most closely related to V. cholerae (GenBank accession number: JN555611). Artificially infected grass carp that died exhibited the same disease symptoms as those of naturally infected fish. An amplified band in the corresponding 564-bp position was detected as the virulence factor, and it was the same as that of the V. cholerae virulence factor ctxA. Drug sensitivity tests showed that V. cholerae was resistant to penicillin, tobramycin, cotrimoxazole, and amoxicillin, and was highly sensitive to cefuroxime, amikacin, tetracycline, and nitrofurantoin. These could possibly be used in the treatment of this disease. The findings of this study can be used as a reference for disease control and health management in the cultivation of C. Idellus.
Effect of the Substitution of Fish Oil with a Mixture of Plant-Based Oils in Diets of Rainbow Trout (Oncorhynchus mykiss Walbaum) Fingerlings on Growth, Phosphorus and Nitrogen Excretion
Authors: Reyes Mirna Leandra Enríquez , Velázquez Esmeralda Analleli Ramírez , Hernández Luis Héctor Hernández , Araiza Mario Alfredo Fernández
Published: February 2021

A feeding trial was performed to determine the effect of substituting fish oil with a 1:1 mixture of soybean and linseed oil on growth, phosphorus and nitrogen excretion, and lipid deposition of rainbow trout fingerlings. Diets with soy protein concentrate and soybean meal were prepared with 25, 50, and 75% substitution of fish oil with plant oils. Soy protein concentrate and soybean meal were used with fish oil at 100% in the control diet. Triplicate groups of 15 juveniles with an initial weight of 0.74 ± 0.05 g (mean ± standard error) were fed the experimental diets for 70 days. Growth performance, protein, and lipid digestibility, oxygen consumption, nitrogen, and phosphorus excretion, and lipid deposition (liver and muscle) were determined. The mixture of plant oils did not affect the growth performance of fingerlings. Apparent digestibility of lipids decreased as the fish oil in the diet decreased. A significant decrease of phosphorus excretion was observed as plant oils in the diets were increased. Lipid deposition was higher in liver unrelated to plant oil concentration in the diet. The results show that it is possible to use high quantities of plant ingredients in the diets without affecting the growth performance and lipid deposition, as well as significantly decreasing phosphorus excretion.
Effects of Trehalose, Bovine Serum Albumin, and Sucrose, on the Integrity of the Plasma Membrane of Pseudosciaena crocea Semen after Cryopreservation
Authors: Cheng Shun , Sheng Zhang , Zhu Jun-Quan , Wu Xiong-Fei
Published: February 2021

Cryopreservation and the effect of additives on the plasma membrane stability, motility, enzyme activity, membrane lipid composition, and ultrastructural injury of sperm of Pseudosciaena crocea, were examined in this study. Results indicated that the addition of trehalose (TH) and bovine serum albumin (BSA) provided significantly better results in the motility test compared to sucrose. Some BSA groups, showed significantly increased semen motility and effective enzyme activity. There were no significant differences between the cholesterol (CHO) composition for fresh sperm and cryopreserved sperm stored in 3 g/L BSA or 8.56 g/L TH+3 g/L BSA. Ultrastructural injury included damaged membrane, lost mitochondria, or broken flagella, whereas the majority of the freeze-thawed sperm remained morphologically normal. In conclusion, the addition of 3 g/L BSA and 8.56 g/L TH+3 g/L BSA significantly increased semen quality
Effect of Dietary Cornstarch Level on The Growth Performance of Japanese Seabass (Lateolabrax japonicus) in Grow-Out Phase
Authors: Zheng Keke , Dou Bingshuai , Xu Houguo , Liang Mengqing
Published: February 2021

A 10-week growth trial was conducted to investigate the effect of dietary cornstarch levels on the growth performance, body composition, liver/muscle glycogen, and selected serum biomarkers, of Japanese seabass in grow-out phase. Six isonitrogenous and isolipidic diets containing graded levels (0%, 6%, 12%, 18%, 24%, 30%) of cornstarch were fed to Japanese seabass (initial weight 343g). Weight gain (WG) significantly increased up to 18% with increasing dietary cornstarch, and then reached a plateau. There was no significant difference in WG between fish fed 18%, 24%, or 30% cornstarch (P>0.05). Based on WG, the optimal dietary cornstarch level of Japanese seabass estimated by second-order polynomial model was 27.0%. Body protein and lipid content as well as total cholesterol and triglycerides in serum showed similar trends, i.e. increasing at first and then reaching a plateau despite increasing levels of dietary cornstarch. Ash content decreased at first and then reached a plateau with increasing dietary cornstarch. Hepatosomatic index and liver glycogen significantly increased with increasing dietary cornstarch (P<0.05) while muscle glycogen, the condition factor was not influenced by dietary treatments. Serum glucose significantly increased with increasing dietary cornstarch and then decreased (P<0.05). Results of this study suggest the provision of adequate dietary cornstarch (>18%) could improve the growth performance of Japanese seabass and the optimal dietary cornstarch level is 27.0% during grow out phase.
Growth, Survival and Fatty Acid Composition of Freshwater Crayfish (Astacus leptodactylus) Juveniles Fed Enriched Daphnia magna as an Alternative to Artemia
Authors: Koca Seval Bahadir , Yigit Nalan Ozgur , Uzunmehmetoglu Esra , Guclu Zekiye , Diken Gurkan , Eralp Hasan
Published: February 2021

This experiment was conducted to investigate the effects Daphnia magna enriched with lipid emulsions as an alternative to Artemia, on growth, survival rate, and fatty acid composition of freshwater crayfish (Astacus leptodactylus Esch. 1823). The four treatment groups were (a) unenriched Artemia (UEA), (b) unenriched D. magna (UED), (c) D. magna enriched with redpepper emulsion (DER), and (d) D. magna enriched with anchovy oil emulsion (DEA). All tests were carried out in triplicate for 30 days. The crayfish (mean weight 0.12g) were fed ad libitum once daily. At the end of experiment, the highest eicosapentaenoic acid, 20:5n-3 (EPA) level was found in the DEA group (5.77%). The highest DHA (docosahexaenoic acid, 22:6n-3) level was found in the DER group (2.73%) which was statistically similar to the DEA group. In addition, high n-3 HUFA (high unsaturated fatty acid) levels were detected in enriched D. magna groups with emulsions. However, high EPA levels in enriched D. magna groups with emulsions were not reflected in crayfish tissues, but DHA level was reflected in crayfish tissues fed with anchovy oil emulsion. The crayfish fed with D. magna showed similar growth to that of the Artemia fed groups. The growth of the enriched D. magna groups did not differ.
Effects of Enzyme-Producing Probiotic Bacteria Isolated from the Gastrointestinal Tract of Trout on the Growth Performance, Survival, and Digestive Enzyme Activity of Rainbow Trout Fry (Oncorhynchus mykiss)
Authors: Koca Seval Bahadır , Yigit Nalan Özgür , Didinen Behire Işıl , Metin Secil , Bayrak Halit , Onuk Ertan Emek , İlhan İlter , Eralp Hasan , Diler İbrahim
Published: February 2021

In this study, we investigated the effects of enzyme-producing probiotic bacteria isolated from the gastrointestinal tract of rainbow trout on the growth performance, feed conversion ratio, and digestive enzyme activity, of fry (Oncorhynchus mykiss). Three isolates (G8/2013, T7/2013 and U5/2013) of candidate bacteria elicited the highest protease, lipase, and amylase activities, respectively. Isolates were identified as Aeromonas sp., Bacillus sp. and Citrobacter braakii by morphological, physiological, biochemical characterizations as well as 16S rRNA gene sequence analysis. The fry basal diet was supplemented with probiotics at varying concentrations; G8 group, Aeromonas sp. 1.72 x 108 CFU/g; U5 group, Bacillus sp. 3.01 x 108 CFU/g; T7 group, C. braakii 2.96 x 108 CFU/g and a mixed group (same bacterial concentrations), and control group (no bacteria). The rainbow trout fry were fed ad libitum in triplicate treatments with supplemented and non-supplemented probiotic diets for 70-days. The total bacterial count in the intestine was significantly higher in the mixed group (30th and 50th days) and U5 group (50th and 70th days) compared with the control group. However, there was no significant difference in weight gain, specific growth rate (SGR), feed conversion ratio (FCR), nutrient digestibility, or digestive enzyme activity among the groups.a
Effects of Dietary Cholesterol Levels on the Growth, Molt Performance, and Immunity of Juvenile Swimming Crab, Portunus trituberculatus
Authors: Han Tao , Wang Jiteng , Li Xinyu , Yang Yunxia , Wang Jianxin , Hu Shunxin , Jiang Yudong , Mu Changkao , Wang Chunlin
Published: February 2021

The effects of dietary cholesterol levels on growth, molt performance, and immunity of juvenile swimming crab Portunus trituberculatus, were investigated at four cholesterol levels (0.2%-1.4%) of purified diets. Each diet was fed in triplicate to 18 crabs per replicate for 50 days. Crabs fed the diet with 1.0% cholesterol showed significantly higher (P<0.05) specific growth rate (SGR) than the other groups, who suffered from relatively lower molt death syndrome (MDS). Cholesterol content in the serum, whole body, and hepatopancreas increased in relation to dietary cholesterol. Muscle lipid content was significantly higher (P<0.05) in crabs fed the diet with 0.2% cholesterol compared to the other treatments. Crabs fed moderate dietary cholesterol levels showed higher alkaline phosphatase (AKP) or acid phosphatase (ACP) levels than those fed 0.2% or 1.4% cholesterol diets. The present study also showed that dietary cholesterol supplementation generally increased serum superoxide dismutase (SOD) activity. Overall, moderate dietary cholesterol (1.0 %) enhanced the performance of growth, survival, molting, and immunity of juvenile swimming crab P. trituberculatus.
Biochemical Components of Different Colored Strains of Cultured Japanese Scallop (Mizuhopecten yessoensis) Under Different Cultivation Systems
Authors: Hao Zhenlin , Yang Limeng , Zhan Yaoyao , Tian Ying , Ding Jun , Pang Yunlong , Chang Yaqing
Published: February 2021

In this study, the water and total fat content, total crude protein, ash, fatty acids, amino acids and mineral elements of scallop adductor muscle were used to understand the biochemical components of different colored strain of Japanese scallop, Mizuhopecten yessoensis, cultured using different cultivation methods. Common scallops had slightly higher moisture, and total protein content, significantly higher total fat content, and significantly lower ash content than ivory white scallops when cultivated under both suspended and bottom culture conditions. For scallops of both colors, suspended culture individuals had slightly higher moisture, total protein content, significantly lower total fat and ash content, compared to bottom culture conditions. Most amino acids were more abundant in scallops from the bottom culture group than in scallops from the suspended culture group. The ivory white scallops contained slightly higher amounts of total amino acids, essential amino acids, and flavor-imparting amino acids, than the common scallops under a given culture method. In the suspended culture group, common scallops had higher content of unsaturated fatty acids, mono-unsaturated fatty acids, polyunsaturated fatty acids, lower contents of eicosapentaenoic acid and docosahexaenoic acid, compared with ivory white scallops. In the bottom culture group, common scallops contained more unsaturated fatty acids, polyunsaturated fatty acids, eicosapentaenoic acid and docosahexaenoic acid compared with ivory white scallops. In common scallops, levels of mineral elements (apart from Fe and Mg) were higher in suspended culture than in bottom culture. Levels of mineral elements in ivory white scallops in suspended culture were higher than or the same as those in bottom culture with the exception of K and Mn. In conclusion, different cultivation methods and shell color of M. yessoensis affected biochemical composition, amino acid content, fatty acid content, and mineral element content of the scallops. The research results may provide useful information for selective breeding, culture methods, deep processing, and comprehensive utilization of M. yessoensis.
Characterization of Nitrifying Bacterial Community in a Mariculture Wastewater Treatment Using SBR System
Authors: Che J. , Wang L. L. , Wang X. T. , Yang G. J. , Yang  , Xu W. P. , Xu Y. P.
Published: February 2021

Sequencing batch reactors (SBR) have been used in the biological treatment of aquaculture wastewater. In this study, we investigated the microbial community of a SBR that used diatomite earth (20 g/L) as the sludge carrier material. Marine wastewater in which ammonia content was 42.08 to 55.88 mg/L was supplied to the SBR every 12 h over a treatment period of 65 days. During the first 20 days, the concentration of NH4-N decreased gradually, while nitrite (NO2-N) became the major nitrogen compound, reminiscent of the development of an ammonia-oxidizing process. Over the next 20 days, the concentration of NH4-N decreased further due to conversion to NO3-N. More than 99% of the NH4-N was converted to NO3-N over a period of 40-65 days. Denaturing gradient gel electrophoresis (DGGE) assay showed that bacteria of the genus Flavobacterium were present during the entire treatment period, while α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, and Sphingobacteriia started to accumulate after the first 20 days. Fluorescence in situ hybridization (FISH) assay identified Nitrobacter and Nitrosomonas as the main bacteria involved in the conversion of NH4-N to NO3-N. Diatomite earth therefore acted as an efficient sludge carrier by shortening the settling time and facilitating bacterial colonization. This SBR was capable of rapid removal of NH4-N. This warrants further investigation at the pilot-scale in an actual mariculture farm.
DNA Barcoding Analysis of Commercial Freshwater Fish Species Cultured in China
Authors: Wang Qian , Dai Wei , Wang Xiaomei , Yang Jianxin , Zhou Wenli
Published: February 2021

In this study, thirteen commercial freshwater fish species cultured in China, and one hybrid F1 (Megalobrama amblycephala ♀ × Erythroculter ilishaeformis ♂), were barcoded for a 860 bp region of the mitochondrial cytochrome oxidase subunit I (COI) gene. The results showed that a neighbor-joining (NJ) tree was constructed based on COI sequence clustered species in accordance with their taxonomic classification. Hybrid F1 could not be differentiated from M.amblycephalaj in the neighbor-joining (NJ) tree. There was a significant negative correlation between interspecific hybrid compatibility and genetic distance (R2 = 0.96). Hybrid compatibility can be predicted by the interspecific genetic distance.
Dietary Phosphorus Requirements of Juvenile Hybrid Tilapia (Oreochromis niloticus♀× O. Aureus♂) Fed Fishmeal-free Practical Diets
Authors: Zhang Yu-Fan , Yue Yi-Rong , Tian Li-Xia , Liu Yong-Jian , Wang An-Li , Yang Hui-Jun , Liang Gui-Ying , Ye Chao-Xia
Published: February 2021

A growth trial was conducted to estimate the optimum levels of dietary phosphorus (P) for juvenile hybrid tilapia (Oreochromis niloticus × O. aureus) fed fishmeal-free practical diets. Hybrid tilapia (1.68 ± 0.08 g) were fed diets containing various levels (0.0%, 0.2%, 0.4%, 0.6%, 0.8% and 1.0%) of additional inorganic phosphorus for 10 weeks using two different sources of phosphorus：calcium dihydrogen phosphate (MCP), and sodium dihydrogen phosphate (MSP). Hybrid tilapia fed the P-supplemented diets showed significantly higher weight gain (WG) and mineral deposition than those fed the unsupplemented diet. Based on weight gain and vertebral phosphorus content, the available phosphorus requirements of hybrid tilapia were estimated as 1% and 1.31% (0.6% and 0.9% based on additional phosphorus content) respectively, when MSP was used as a phosphorus source. When MCP was the phosphorus source, the requirement estimated for weight gain was 0.95% (0.61% based on additional phosphorus content). In addition, MCP contributed to increased growth and a higher mineral deposition rate than did MSP, in freshwater-reared hybrid tilapia.