# Occurrence of Malabar Snakehead,Channa diplogramma (Perciformes: Channidae) from River Valapattanam, Western Ghats of Kerala, India

Authors: Sajan Sajeevan; Anna Mercy T. Varkey; Mithun Sukumaran
Journal: Advances in Ecology
 (2014)

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## Abstract

We report the occurrence ofChanna diplogramma in the Valapattanam River in March 2013 and this study adds to the species record of C. diplogramma in terms of diversity and range distribution in the River Valapattanam and South India.


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## Body

## 1. Introduction

Freshwater snakehead fishes of the family Channidae have widespread distribution in the tropics [1], represented by 38 species, of which 35 are of the Asian genusChanna [2] and three of the African genusParachanna [1, 3, 4]. The Western Ghats biodiversity of India extends along the west coast and is crisscrossed with many streams, which form the major rivers draining water to the plains of Peninsular India [5]. The freshwater fish diversity in the Western Ghats hotspots is very high [6], with 320 species belonging to 212 endemic species 47% being under Threatened or Near Threatened categories and 23% being under Data Deficient or Not Evaluated categories [7]. The Valapattanam River is one of the west-flowing Rivers in the Western Ghats region of India and the main tributaries are Srikandapurampuzha, Bavalipuzha, Venipuzha, and Aralampuzha. In this paper, we report the occurrence and biometric characteristics ofC. diplogramma (Day 1865) [8] from the river Valapattanam, Western Ghats of Kerala, India.


## 2. Materials and Methods

A specimen ofC. diplogramma (Figure 1) was caught with an encircling net (length 50 meter; height 1.5 meter; mesh size 0.8 mm) from the River Valapattanam, northern Kerala (11.93° N, 75.30° E) on 15 March 2013. The morphometric measurements of the formalin-preserved specimen were measured with a Vernier calliper to the nearest 0.1 millimetres and weighed to the nearest 0.01 gram using an electric balance (Sartorius-GD-603). The morphometric measurements and meristic counts were made by following Ng et al. [9]. Measurements of body parts are reported as percentage of standard length (%SL) and measurements of subunits of head are reported as percentage of head length (%HL). The specimen was preserved in 4% formaldehyde solution and deposited in the Museum of the Faculty of Fisheries, College of Fisheries, Kerala University of Fisheries and Ocean Studies, Panangad, Kerala, India (FRM-CH-DIP/2013-1).Figure 1
Channa diplogrammacaught from the River Valapattanam (lateral view).


## 3. Results and Discussion

Channa diplogramma was first described asOphiocephalus diplogramma (Day 1865) based on one juvenile specimen (42 mm in length) collected near the mouth of the Cochin estuary in the port city of Cochin (Kerala, India). The close similarity of this juvenile specimen withC. micropeltes, originally described by Cuvier and Valenciennes [10] from Indonesia, may have misled author to synonymiseC. diplogramma withC. micropeltes [11]. Recently researchers suggested thatC. diplogramma is distinct fromC. micropeltes and should be considered as a valid species [12, 13]. After 134 years of it being synonymised,C. diplogramma is known to be a valid endemic species of Peninsular India [11].Channa diplogrammais endemic to southern Western Ghats region of India, where it has been reported from the River Meenachil, Manimala, Pampa, Achankovil, and Kallada in Kerala state, as well as the River Chittar and Tambraparni in Tamil Nadu state [11, 14, 15]. Benziger et al. [11] reported that they used comparative specimens ofC. diplogramma from Canara and Mangalore region of south India, but there is no specific record from River Valapattanam [11]. This species has not been reported from the Valapattanam River in earlier works [16, 17]. Hence, this current record adds to the recorded ichthyodiversity of River Valapattanam in Kerala (Figure 2).Figure 2
Distribution ofChanna diplogramma in the rivers of Kerala.The morphometric and meristic characters of the collectedC. diplogrammaare presented in Tables 1 and 2. All the morphometric measurements and meristic counts of the current specimen were in the prescribed range forC. diplogrammaas described by Benziger et al. [11]. Some researchers have used molecular analysis methods for the taxonomic identification of a species [2, 12, 18, 19]; however, we could not follow the molecular analysis in the current study. Benziger et al. [11] reported thatC. diplogramma,collected from the riverine system of Kerala, had 103–105 lateral line scales, which was more than all other species in this genus. Similarly, the current specimen also had 104 lateral line scales and has a relatively long broad body with a laterally compressed head.Table 1
Morphometric measurements of theChanna diplogramma.
Character
Measurement (mm)
% of Standard Length
Total length
534.1
Standard length
437.1
Head length
145.2
33.2
Head width
85.1
19.5
Head depth
73.6
16.8
Body depth
92.0
21.1
Body width
91.3
20.9
Predorsal length
154.2
35.3
Preanal length
221.1
50.6
Prepectoral length
149.1
34.1
Prepelvic length
155.3
35.5
Dorsal fin base length
282.1
64.5
Anal fin base length
169.1
38.7
Caudal peduncle length
61.1
14.0
Caudal peduncle depth
58.5
13.4
Caudal fin length
97.1
22.2
Orbital diameter
16.1
3.6
Preorbital length
33.2
7.6
Postorbital length
108.9
24.9
Inter orbital width
48.9
11.2
Jaw length
61.2
14.0
Jaw width
54.1
12.4
Gape width
21.1
4.8
Dorsal fin length
36.1
8.2
Pectoral fin length
65.6
15.0
Pectoral fin base length
24.1
5.5
Pelvic fin length
55.1
12.6
Anal fin length
32.1
7.3
Character
Measurement
% of Head length
Head width
85.1
58.6
Head depth
73.6
50.7
Orbital diameter
16.1
11.1
Preorbital length
33.2
22.9
Postorbital length
108.9
75.0
Inter orbital width
48.9
33.7
Jaw length
61.2
42.1
Jaw width
54.1
37.3
Gape width
21.1
14.5Table 2
Meristic data of theChanna diplogramma.
Character
Number
Dorsal fin rays
42
Anal fin rays
27
Pectoral fin rays
15
Pelvic fin rays
6
Lateral line scales
104
Scales above Lateral line
7
Scales below Lateral Line
16Snakeheads are very hardy animals due to the presence of several biological features that they share among their family [18]. In the present studyC. diplogramma was collected from middle stream part of the river, pool type of habitat with riparian shade and bottom with rock, gravel, and sand. Banks of the site was supported with shrubs and trees giving strong shade into the water. In nature, snakeheads are carnivorous which feed only on live animals including small fishes, insects, crustaceans, frogs, and even baby turtles [20]. Mohsin and Ambak [21] and Roberts [22] noted thatC. micropeltes kills more individual fish than it actually eats (i.e., not all prey is consumed); likewise,C. diplogramma may possibly be a biological threat to the small indigenous freshwater fishes in these rivers [18]. To underst and its effects over indigenous freshwater fish diversity, more studies are to be conducted.Due to the attractive colour pattern of juveniles ofC. diplogramma,they have been overexploited from the wild for the international aquarium pet trade [23]. However, this profitable business sometimes poses a threat to the environment especially in places where snakehead is not a native fish since some of the fish find their way into dams, rivers, and other water bodies, either by accident or otherwise by being released by traders or by hobbyists when they mature into less attractive colours [18]. Channa diplogrammashows a similar pattern of body colouration as inC. micropeltes[11]; the current specimen showed to be dark blue with white spots along the whole of its profile down to its white underside. According to Benziger et al. [11],C. diplogramma shows multiple colour stages during its life history, which makes local fishermen believe that they are different species. Because of this colour differentiation,C. diplogramma is locally known by different vernacular names such as Puli vaka, Kari vaka
, Manal vaka, Charal vaka, and Vaka varal. The current female specimen measured 534.1 mm in total length and 1720 g in body weight. The spent stage of ovarian maturity was observed in the current specimen ofC. diplogramma caught in March, which may be helpful for future biological and conservation studies inC. diplogrammaThe population ofC. diplogrammais declining due to the overexploitation for consumption and aquarium trading [1, 11]. A recent study revealed thatC. diplogramma contributed 0.79 tonnes in the exploited fishery from River Pampa [24]. Kurup and Ranjeeth [25] reported that the population ofC. diplogrammahas declined significantly over the last two decades in the rivers of Kerala (>90%). Kurup [26] noticed that this species was subjected to alarming decline in its population due to destructive type of fishing activities including dynamiting and poisoning, EUS, habitat alteration, and pollution. Consulting the local fishermen and fish collectors in the River Valapattanam, it is known thatC. diplogrammais caught occasionally by artisanal fishing, namely, seine netting, gill netting, or long lining. Our personal observations and discussions with local fishermen reveal that most of the extensive fishing ofC. diplogrammawas carried out during the monsoon season. Habitat destruction and sand mining in the river basin of Valapattanam have posed serious problems to the freshwater fish population by affecting their breeding and spawning grounds. Due to its restricted distribution, small population size, illegal fishing, and anthropogenic pressure to its natural habitats, the species is classified under Vulnerable by the IUCN [27]. However, the present record is nevertheless significant in extending recorded distribution ofC. diplogrammain the Western Ghats of India.



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*Source: 145056-2014-07-08.xml*