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|***Dedicated To Tribal Aquaculture Programs***
      Fish Jumping
          **June 2001 ~ Volume 36****Coordinator:
                  Frank G. Stone 
                  (715-682-6185) Ext. 12
                  U.S. Fish and
                  Wildlife Service
                Email: [email protected]** | Fish Jumping | **June 2001 ~ Volume 36** | **Coordinator:
                  Frank G. Stone 
                  (715-682-6185) Ext. 12
                  U.S. Fish and
                  Wildlife Service
                Email: [email protected]** | **Coordinator:
                  Frank G. Stone 
                  (715-682-6185) Ext. 12
                  U.S. Fish and
                  Wildlife Service
                Email: [email protected]**
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# Topics
  of Interest:

> MTAN ArrowHydrogen Peroxide For Treating Eggs and Fish!
>   MTAN ArrowDisinfect Those Hatchery Tools - Please
>   MTAN ArrowAeration For Aquaculture
>   MTAN ArrowVenturi Aeration Process
>   MTAN ArrowMasternet

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## **Hydrogen Peroxide-A Potential Broad Spectrum Fish  Therapeutant**Authors: Jeff Rach, Mark Gaikowski, and Theresa Schreier

Studies conducted at the Upper  Midwest Environmental  Sciences Center  (UMESC; USGS) La Crosse, Wisconsin determined that hydrogen peroxide  was effective for controlling fungus on fish eggs. Additional attributes of  hydrogen peroxide are that it is environmentally compatible decomposing into  water and oxygen and the compound does not accumulate in fish tissue. Based on  these early studies and the chemical properties of the compound the U.S. Food  and Drug Administration (FDA) classified hydrogen peroxide as a low regulatory  priority drug when used at concentrations up to 500 mg/L to control fungal  infections on fish and their eggs. Recent research funded by the International  Association of Fish and Wildlife Agencies (IAFWA) has indicated hydrogen  peroxide may have potential as a broad spectrum fish therapeutant. However, FDA  requires further research and data submissions before granting a New Animal  Drug Approval (NADA) for additional uses for hydrogen peroxide. Additional  studies are being conducted to gain FDA approvals for using hydrogen peroxide  to control fungal and bacterial infections and parasitic infestations on  freshwater fish. An overview of hydrogen peroxide research conducted at the  UMESC will be presented in this article along with recent hydrogen peroxide  publications.

**SUMMARY OF RECENT STUDIES**

## Hydrogen Peroxide Egg TreatmentsA. Rach, J.J., M.P. Gaikowski, G.E. Howe & T.M.  Schreier. 1998. Safety of hydrogen peroxide treatments on warm- and coolwater  fish eggs.

Methods: The efficacy of hydrogen peroxide (35%) to control  egg mortality of eight freshwater fish species was evaluated in a miniature egg  jar incubation system. Non-eyed eggs of northern pike, walleye, yellow perch,  white sucker, lake sturgeon, paddlefish, common carp, and channel catfish were  cultured in egg jars or aquaria and treated for 15 minutes every weekday with  0, (untreated control) 500 (northern pike only), 1,000, 3,000, or 6,000 mg/L of  hydrogen peroxide until all viable eggs hatched.

Results: In comparison to the controls, hydrogen peroxide  controlled or eliminated the spread of fungus to healthy eggs in most species  tested (Table 1). Fungus was present on all untreated control eggs of the  species tested, except for the northern pike eggs which were free of fungus on  all eggs tested (including treatment groups). Only the lake sturgeon had  visible fungus present on treated eggs. Treated eggs of all other species were  free of fungus. Hydrogen peroxide treatments of 1,000 and 3,000 mg/L increased  hatch in all species in comparison to the control group, with the exception of  the paddlefish eggs in the 3,000 mg/L group. The highest percent hatch for all  species was in the 1,000 mg/L treatment group except lake sturgeon where the  highest hatch was in the 3,000 mg/L treatment group.

**Table 1**. Percent hatch (mean of three jars with standard  deviation in parentheses) of fish eggs treated with 0, 500, 1,000, 3,000, and  6,000 mg/L hydrogen peroxide for 15 minutes every week day until hatch.

|Mean Percent Hatch
    Treatment Concentrations (mg/L)
|------------------------------------------------------
|Fish Species                                          
|Northern Pike                                         
|Walleye                                               
|Yellow Perch                                          
|White Sucker                                          
|Lake Sturgeon                                         
|Paddlefish                                            
|Common Carp                                           
|Channel Catfish                                       

a Not tested.
b Fungus observed on eggs.



## B. Rach, J. J. Unpublished Data. Efficacy of hydrogen  peroxide treatments on rainbow trout fish eggs

**Methods**: The efficacy of hydrogen peroxide to control egg  mortality of rainbow trout was evaluated in a miniature egg jar incubation  system. Non-eyed eggs of rainbow trout were cultured in egg jars and treated  for 15 or 45 minutes every other day with 0, (untreated control) 1,000, 3,000,  5,000, or 10,000 mg/L of hydrogen peroxide until the eggs became eyed. Eyed  eggs of rainbow trout were cultured in egg jars and treated for 15 or 45  minutes every other day with 0 (untreated control) 1,000, 3,000, 5,000, or  10,000 mg/L of hydrogen peroxide until the viable eggs hatched (eyed egg  treatments).

**Results**: In all the rainbow trout non-eyed toxicity tests  (Table 2), hydrogen peroxide treatments reduced the probability of hatch in a  dose-dependent manner. The 15-minute treatments were significantly less toxic  than 45-minute treatments and treatments conducted at 12EC were less toxic than  treatments conducted at 15EC. In all the rainbow trout eyed egg toxicity tests, all treatment groups had similar percent mean egg hatch. There  appeared to be no significant differences in toxicity (percent mean egg hatch)  for the 15- or 45- minute treatments. Also, there appeared to be no significant  differences in toxicity (percent mean egg hatch) between the 12EC and 15EC  treatments. Rainbow trout appear to have a sensitive period (70 - 140_C daily  temperature units) in egg development where the eggs may be sensitive to 1,000  mg/L or greater treatments. However, after this period is passed, the eyed eggs  become very insensitive to hydrogen peroxide exposure.

**Table 2**. Percent eye-up (mean of three jars with standard  deviation in parentheses) of rainbow trout eggs treated with 0, 1,000, 3,000,  5,000, or 10,000 mg/L hydrogen peroxide every weekday for 15 or 45 minutes  until hatch was complete.



|Mean Percent Eye-up
        Treatment Concentrations (mg/L)
|-----------------------------------------------------------
|                                                           
|12EC, for 15 min.                                          
|12EC, for 45 min.                                          
|15EC, for 15 min.                                          
|15EC, for 45 min.                                          

a Same set of control fish used for both treatments.
b Not tested.



## Hydrogen Peroxide Treatment of Bacterial InfestationsRach J. J., M. P. Gaikowski, and R. T. Ramsay. 2000.  Efficacy of Hydrogen Peroxide to Control Mortalities Associated with Bacterial  Gill Disease Infections on Hatchery Reared Salmonids.

**Methods**: The efficacy of hydrogen peroxide to control  mortalities associated with Bacterial Gill Disease (BGD) was evaluated in three  trials conducted at two Wisconsin Department of Natural Resources hatcheries.  Treatments were conducted in a portable test system consisting of 12  individually plumbed 20 L tanks. Each test tank was supplied with a continuous  flow of water. Microscopic examination of the fish gills before treatment  revealed gill damage and the presence of bacteria indicative of BGD. Fish in  the test system were exposed to three static hydrogen peroxide treatments (30  or 60 minute exposures) administered once daily every-other-day on three occasions.  Exposures were administered for 60 minutes in trials 1 (brown trout) and 2  (chinook salmon), and shortened to 30 min in trial 3 (rainbow trout).

**Results**: In all three trials, at least one of the hydrogen  peroxide treatment regimens reduced cumulative fish mortality in comparison  with the controls. The percent mortalities for individual species tested in  separate trials were as follows: Trial 1 (brown trout) control - 12%, 50 FL/L -  0%, 100 FL/L - 7%, 200 FL/L - 37%; Trial 2 (chinook salmon) control - 21%,  50 FL/L - 7.6%, 100 FL/L - 22%, and 200 FL/L - 72%; Trial 3 (rainbow trout)  control - 31%, 50 FL/L - 25%, 100 FL/L - 14%, and 200 FL/L - 7%. Exposures of  200 FL/L for 60 minute increased the risk of mortality to brown trout and  chinook salmon relative to other treatment concentrations. Exposures up to 200  FL/L hydrogen peroxide for 30 minute decreased the risk of mortality to rainbow  trout. Post-treatment qualitative gill examination indicated that gills of the  treated fish appeared normal while the gills of control fish exhibited pale  coloration, clubbing of filaments, and lamellar fusion. Based on the efficacy  data, two static bath treatment regimens were effective in the control of BGD;  hydrogen peroxide administered at concentrations of 50 to 100 FL/L as a 60  minute exposure or hydrogen peroxide administered at concentrations of 50 to  200 FL/L as a 30 minute exposure.

## Hydrogen Peroxide Treatment of Parasitic InfestationsRach J. J., M. P. Gaikowski, and R. T. Ramsay. 2001.  Efficacy of Hydrogen Peroxide to Control Parasitic Infestations on Hatchery  Reared Fish.

**Methods**: The efficacy of hydrogen peroxide to control  external parasitic infestations on juvenile (10-33g) rainbow trout was  evaluated in three clinical field trials conducted at two Wisconsin Department  of Natural Resources hatcheries. In separate trials, rainbow trout were  transferred from a source raceway into a test system of 12 individually plumbed  tanks. Pre- and post-treatment skin scrapes and gill wet mounts of test fish  were microscopically examined to identify and enumerate external parasites.  Infestation severity was classified as nonexistent (0 organisms), low (1-10  organisms), moderate (11-20), or severe ($21). Fish were exposed to hydrogen  peroxide concentrations ranging from 0 to 500 FL/L for 30 min once  every-other-day for a total of three treatments.

**Results**: In trial 1, pretreatment skin examinations revealed  a severe infestation of Ambiphrya (Protozoan) on all fish examined.  Post-treatment skin examinations conducted within 24 hours of the last  treatment indicated that all hydrogen peroxide treatments eliminated Ambiphrya,  whereas control fish remained severely infested with the protozoan. In trial 2,  pretreatment examinations of skin and gill samples indicated a severe infestation  of the trematode Gyrodactylus (skin) and the protozoan Trichodina (gills) on  all fish. Post-treatment examinations conducted within 24 hours of the last  treatment revealed Gyrodactylus was eliminated from the skin of all treated  fish, however, the severe Trichodina infestation remained on the gills of the  test fish. All control fish remained severely infested with both parasites. In  trial 3, a severe Ambiphrya infestation was found on the skin of test fish  prior to treatment. Post treatment examinations conducted 14 days after the  last treatment revealed 56% of the fish were parasite free, while the remaining  test fish had low infestation levels (fish probably became reinfested with  parasites). Control fish remained severely infested with the parasite. Based on  the efficacy data, all hydrogen peroxide treatment regimens were efficacious in  the control of the Ambiphrya and Gyrodactylus but not Trichodina.

## Selection of Hydrogen Peroxide Treatment Regimens

Chemical therapy for disease control is a necessary and  common practice in aquaculture. There seems to be a misconception that one  treatment regimen (chemical concentration applied for a specific time period)  can be used in all circumstances. In reality fish disease treatments are not an  exact science, because fish are cultured in an environment where numerous  variables are encountered that affect the health and ability of a fish to  withstand a chemical treatment.

A disease outbreak is dependent on three major components;  the disease organism, fish host, and environmental conditions. Numerous  variables can effect the balance between each of the disease outbreak  components and fish culturists should consider these variables before selecting  a treatment regimen. These variables include; state of health of the fish, fish  species sensitivity to the therapeutant, fish life stage, severity of the  disease infestation, presence or absence of the disease organism in the culture  water source, water quality, and weather conditions. For example, if the fish  are severely stressed and infested with numerous parasites the treatment  regimen selected should be less stressful (lower concentration or exposure  time) than a treatment administered to fish just coming down with a disease.

The selection of treatment regimen should always be defined  within the limits (range of acceptable treatment concentrations and exposure  times) defined on the chemical label. Once a specific treatment regimen has  been selected a preliminary bioassay should be conducted on a small sample of fish  to validate the safety of the proposed treatment regimen.

Before conducting a chemical treatment, fish culturists  should be aware of the length of time required to flush the chemical from the  culture unit after the treatment termination. The flushing rate can be  determined by dividing the volume of the culture unit by the flow rate or water  samples can be periodically analyzed for chemical concentration. If the  chemical concentration cannot be rapidly flushed from the culture unit, fish  toxicity could result. In instances when the chemical concentration cannot be  significantly reduced within 5-10 minutes, the treatment regimens (exposure  time or concentration) may have to be reduced.

Fish culturists should analytically verify the accuracy of a  chemical application and document factors that negatively affected the accuracy  of the treatment application. Inaccurate chemical applications are usually the  result of insufficient information on the efficiency of a treatment system to  deliver a specific treatment regimen or inaccurate calculation of chemical  quantities to be delivered. Hydrogen peroxide is a chemical that can be easily  analyzed by a simple titration method. Verification of treatment regimens will  assist with increasing treatment accuracy and improving disease control.



## Disinfect Hatchery Tools and Ponds For Peace Of MindBy: Terry Ott, U.S. Fish and Wildlife Service, LaCrosse Fish  Health Center

Hatchery ToolsProperly disinfecting hatchery equipment can eliminate or  reduce your chances of developing a serious fish disease at your hatchery. It  is well known that prevention is better than cure; this also applies in the  case of disinfection. Many fish diseases are caused by microscopic pathogens,  which are found in the water supplies of fish cultural facilities. How they get  there depends on a number of hatchery operation factors and whether or not your  hatchery has a closed or open water supply. Fish are continually bathed in an  aqueous suspension of microorganisms @good or bad@, and these organisms are  easily transmitted from one raceway pond to another by anything that goes into  the water; brushes, nets, seines, rubber boots, etc. All these items can be  effectively sanitized by dipping, soaking, or rinsing in some form of chemical  disinfectant.

Proper disinfect ion practices at your hatchery are easy and  inexpensive methods of disease control in which you destroy a 'link" in  the transmission cycle of a potential fish pathogen moving throughout your  hatchery. Don 't give a possible fish pathogen a free ride!

Sunshine, in itself ' is a good disinfectant, and few fish  pathogens can last very long under the combined assault of drying and sunshine.  Hatchery tools which have come into contact with a stock of fish should always  be allowed to air-dry in the sun, before coming into contact with another stock  of fish.

If time and sunshine are at a premium one of the best and  cheapest chemical disinfectants is chlorine (HTH). Chlorine levels are reduced  by organic material such as mud, slime, and plant material. So it is very  important to thoroughly clean pond walls and bottoms, before filling ponds to  the top with clean water and adding 200 ppm of HTH. A solution of 200 ppm will  be effective in killing all fish pathogens in one hour. Walls and flooring that  do not come into contact with the 200 ppm HTH can be sprayed with 1000 ppm.  Make sure all safety precautions are followed when using chlorine and hatchery  staff are wearing the proper personal protective equipment. Chlorine is toxic  to all fish at levels above 0.03 ppm. If troughs, tanks, or ponds are  disinfected, the chlorine must be neutralized before it is allowed to drain or  to enter waters containing fish. HTH can be safely neutralized by adding 5.6  grams of sodium thiosulfate for every gallon of 200 ppm HTH solution contained  within the pond.

Store HTH in a cool dry place in its original container. As  with all chemicals received at your hatchery read and understand what is in the  Material Safety Data Sheets before handling any potential hazardous chemical.

The quaternary ammonium compounds, such as Hyamine 1622,  Hyamine 3500, and Roccal can be used at 600 ppm effectively as disinfecting  agents. Net-Dip distributed as Sanaqua by Aquavet,  (http://www.aquavet.com/aquavet.htm) is a buffered chloride compound and is a good  all around disinfectant. Use it in a 30 gallon tub filled with the appropriate  chemical strength and keep it in a convenient location for disinfecting tools.  Any industrial or food service germicidal detergent can also make a good  hatchery equipment sanitizer. At the laboratory we use EXTRA made by Hydrite  Chemical Company, Brookfield, Wisconsin.

Iodophors, sold under the trade names of Betadine,  Wescodyne, and others, incorporate the disinfecting element of iodine, which is  an oxidizing agent. Wescodyne can be purchased from West Chemical Products, New  York and used at a concentration of 3 ounces to 5 gallons water.

Hatchery staff entering and exiting a hatchery building  where fish are raised can eliminate the spread of a potential fish pathogen by  disinfecting the soles of their boots in a foot bath. This can be accomplished  by placing a rubber grated matt or large sponge in the bottom of a plastic  tray. Fill the tray with just enough disinfectant solution to cover the grated  matt or saturate the sponge. This will allow wetting only of the bottom of the  boot. If the entire boot requires disinfection remove the matt or sponge and  add more disinfectant to raise the level above the ankle. It 's important to  change the disinfectant solution in the tray once a week to keep the solution  fresh.

Earthen ponds which have contained fish, should be tilled  with a tractor and agricultural lime spread at a rate of 2,000 pounds per acre,  allowed to dry for several weeks, before new stocks of fish are introduced.

A good house keeping practice at all hatcheries is to keep  hatchery tools used in cleaning ponds, tanks, or troughs, separate from each  other. Supply each set or series of ponds in your facility with its own set of  brooms, brushes, and dip nets. If this is not possible at least keep separate  tools used in brood stock ponds from those used for fry and juvenile fish.  Brood stock often carry microorganisms, which, while not harmful to them, are  easily transmitted to, and can be detrimental to younger fish.

Keep in mind while working at your hatchery that a good  hygiene program is one of the cheapest and best ways to ensure a happy and  healthy stock of fish, and a happy manager too! Those who are to be entrusted  with disinfection must be trained in the use of disinfectants and the  maintenance of disinfecting appliances and first aid measures.



## Aeration For AquacultureA Power Point Presentation:
By: Gregg Raisanen, Alexandria Technical   College,  320-762-4618

(Please click on the images below to view each picture).

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## Venturi Aeration Process for AquacultureBy: John Solonich, Pelham,   NH, 603-635-8239, http://venturi-aeration.com/wpr/

The venturi aerator accomplishes three principal benefits  for aquaculture applications:

1. It adds large quantities of dissolved oxygen (DO) for  supporting and growing various aquatic species, and because it aspirates  ambient air, it is self limiting= preventing hyper oxidation.

2. The venturi aerator strips gases like carbon dioxide  (CO2) and methane, stripping CO2 helps maintain a steady pH level ideal for  enhancing growth of aquatic species.

3. The discharged liquid out of the venturi aerator is used  for mixing and equalization of the contents of the pond or lagoon to prevent  stratification and stagnation. Anoxic liquids at the bottom of the lagoon or  pond are pumped into the venturi aerator and are discharged at the top of the  pond. This affords the highest oxygen transfer.

Venturi Aeration Process

A. Suction lift into a self-priming pump, liquids are pumped  from the bottom of the pond where the liquid has the least amount of dissolved  oxygen and is the coolest. Well screening positioned at the end of the suction  line prevents suction of fish and debris into the pump.

> B. Suction lift pump supplies energy for the venturi  aerator.
>   C. Liquid being pumped through the venturi has dissolved  oxygen transferred into the water from 5.0 mg/L up to 7.5 mg/L of DO, depending  on the temperature of the water.
>   D. The liquids being discharged from the venturi aerator  have a velocity of 2 fps which is used for mixing and equalization. The  discharge is onto the top of the lagoon or pond. A properly aligned discharge  will provide for a well-mixed and equalized lagoon.

**Hydrostatic Head Stream Aeration Using Venturi Aerators**

Venturi Aerators can also be uniquely configured to  condition stream water for non-chemical corrosion control and to add dissolved  oxygen for supporting viability of aquatic species. Venturi aerator units can  be remotely deployed without utilities where there is a drop in elevation of 47  feet as there could be in hilly terrain or with a dam. This 47 foot change in  elevation provides the required 20 psi for optimal operation of a venturi  aerator, however they can be operated at lower elevations at lower pressure  differentials with proportionally reduced performance. The piping configuration  is simple and a siphon would ensure constant flooding of the venturi aerator  supply pipe to allow for changes in stream elevation behind the dam or in an  upstream pool.



## MasternetBy: Linda Hartman, Vice President, Masternet Ltd,  1-800-216-2536, Email: [email protected],www.masternetltd.com

Masternet is a family owned and operated company, started in  1988. We extrude various types of plastic nets and meshes. These products can  be converted to bags, or cut to length per customer requirements. Currently we  are supplying a variety of nets and meshes to the aquaculture industry. Along  with a large variety of sizes, we have a wide range of colors as well.

Being owner operated, we have the flexibility to work on and  develop new products. One of our specialties is working closely with people to  develop new and unique items, that could be utilized in various ways to suit  individual needs. With the vast experience we have in the net industry, we feel  we have a good handle on what can be done, and what may work.





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