Murrels

the presentation provides the details regarding the murrels or snakeheads which includes the basic taxonomy, some of the important species, distribution, special characters, its aquaculture potential, food and feeding habits, sexual dimorphism, parental care, age at maturity, the maturity stages, breeding season, courtship and mating, natural spawning, fecundity, induced spawning using ovaprim and HCG and LHRHa, and also the detailed facts regarding larval reariing.

1. MURRELS Presented by, Akhila . S(2014-01-13), Roshni Joseph(2014-01-38) BFSc 2014 Batch,Kerala University of Fisheries and Ocean Studies,Kochi

2. INTRODUCTION Highly regarded food fish in South and South East Asian Countries Popular fish for aquaculture since they breed in confined water bodies. Aggressive and carnivorous in nature. Also considered a pest fish since they destroy other natural species of a water body where they inhabit.

3. BASIC TAXONOMY Phylum Vertebrata Subphylum Craniata Superclass Gnathostomata Series Pisces Class teleostomi Subclass Actinopterygii Superorder Ostariophysi Order Channiformes Family Channidae (= Ophiocephalidae ) Genus Channa

4. There are about 33 sps of murrels distributed in tropical Asia including Northern China and Africa Species of aquaculture importance: Channa striatus C. punctatus C. marulius C. maculata C. micropeltes

5. Channa striata Bangladesh, Dumuria , Khulna, by Balaram Mahalder Courtesy:fish base

6. Bangladesh, Faridpur fish market, by Shovan Khan Sabuz Channa punctatus Courtesy:fish base

7. Channa   marulius   (Hamilton, 1822) Bangladesh, by Balaram Mahalder Courtesy:fish base

8. Channa maculata Courtesy:fish base

9.   Channa micropeltes Courtesy:fish base

10. DISTRIBUTION The geographic distribution of genus Channa extends from Amur in eastern Siberia to China, Korea, India, Burma, Bangladesh, Afghanistan, Iran, Srilanka , Thailand, Vietnam, Kampuchia , Malaysia, Indonesia, Phillippines , East India and tropical Africa. Channa inhabit all type of freshwater such as rivers, lakes, reservoir, ponds, swamps, canals, ditch.

11. SPECIAL CHARACTERS Ability to breathe atmospheric oxygen- sold alive at high prices in the market Predacious and cannibalistic Known to survive drought by aestivating for months in moist mud Very hardy and can tolerate unfavourable conditions.

12. AQUACULTURE POTENTIAL Most common system of murrel culture is in earthen ponds ranging in size from 800- 1600m³. In Vietnam- cultured in cages moored near the shore or trailed behind fishermen boat Traditional system- in irrigation wells High quality flavour and texture of flesh- regarded as diets for invalids and recuperating patients Generally monoculture practiced, In Taiwan, murrels stocked in carp and tilapia ponds to forage unwanted fishes In Thailand, integrated culture with pig and poultry In Thai, farmers stock 75-460 fry of C. striatus per square metre of pond area trash fish, rice bran and broken rice are fed thrice daily in the ratio 8:1:1

13. FOOD AND FEEDING HABITS Parameswavaran (1975) has made a detailed study on the food and feeding habit of C.marulius in swamps. He found that post larvae are exclusively phytophagus , the bulk constituted by zooplankton and rotifers and also small quantity of protozoans . The phytoplankton encountered were desmids and diatoms. The large post larvae subsists mainly on small aquatic insects and other hemipterans . Aquatic insects predominate the diet of larger juveniles. The species develops piscivorous tendency at this stage.

14. In general, the food and feeding habit of C.striatus is the same as given murrel . They are also highly piscivorous , but a lesser degree than C.marulius . At 151-250 mm size group, C.striatus develop piscivorous tendency. Larger adult are predominating piscivorous constituting their diet mainly with carp minnows, weed fish, small sized murrel etc.. True cannibalism is also observed in fry and juveniles stage. The feeding intensity decrease with the increase in size of the fish; more in juveniles and maximum in adults during maturing and recovering months.

15. Like other murrels C.punctatus is also a carnivore, feeding mainly on the animal food right from the post larval stage, but in different stages of life different diet have been noticed. Spawn and the early fry feed almost exclusively on zooplankton; juveniles consume mainly on aquatic insects; fingerlings feed on bigger sized aquatic insect and partly shrimps, annelids and small fish while adult subsists on medium fish fry, minows , shrimps, worms and insects. The difference in food habit of the species of murrels as observed may be attributed to the variation in the availability of the different food organisms.

16. SEXUAL DIMORPHISM SPECIES MALE FEMALE C.marulius No bulging abdomen. Vent pale round and reddish. Slight bulging of abdomen. C.striatus No bulging abdomen. Vent pale . Anal papilla-like structure with its tip pointed. Slight bulging abdomen. Vent round and reddish. Anal papilla like structure broad, slightly reddish in colour and blunt with reddish dot. C.punctatus No bulging abdomen. Numerous minute black dots on the dark ventral bands. Vent oblong and pale with brown to dark periphery. A pinkish dot may be present as the center. Slight bulging abdomen. Diffused black blotches. A few minute black dots may or may not be present. Vent round, slightly protruding and reddish.

17. Channa striata

18. Channa striata

19. PARENTAL CARE In Channa marulius , the species exhibits deep parental care. They build cup like nests in a weedy margin by inter weaving act of stem and blade of weeds. Both parents guard the egg and fry although at times only one is seen with the brood. Parental care ceases and the young are disposed when attain a size of above 170mm. The degree of negligence is inversely proportional to the size of young one.

20. Parental care

21. AGE AT MATURITY Murrels attain maturity at an age between one and two years Length C. striatus - above 25 cm C. marulius - above 36 cm

22. MATURITY STAGES The following six stages of maturity was observed in the ovary of spotted murrel

23. Stage 1 Ovaries thin, looks ribbon like transparent, whitish grey in colour . Extends to not even half the length of coelom . Stage 2 Ovaries pale yellow, granular in appearance; becomes slightly thicker and longer. Oocytes increase in size and show formation of yolk vesicle in the periphery of ooplasm . Stage 3 Ovaries yellow, granular in appearance, increases in length and width, occupying half of the length of the body cavity. Yolk granules increases in quantity and passes towards periphery of ooplasm . Stage 4 Ovaries enlarge in girth and length; occupy almost entire length of coelom . Ova closely packed, nuclear content not visible. Stage 5 Ovaries attain maximum volume; ova transparent with large yolk granules. Volume is reduced; extrusion of some ova. Stage 6 Spent ovaries shrunken; reddish in colour occupying 3/4 th length of coelom .

24. Breeding and larval rearing

25. BREEDING SEASON Peak breeding season of C. striatus is during the rainy season, but the species seem to breed throughout the year the moderate climate and abundant rainfall in peninsular India provide favourable conditions for breeding of murrels throughout the year In north, these conditions prevelant only for limited period- breeding restricted to monsoon and post monsoon spawns in a variety of habitats such as rivers,lakes , reservoirs, swamps, jheels , bheels , tanks,ponds , paddy fields and even puddles

26. COURTSHIP AND MATING An elaborate courtship with males actively chasing the females precedes spawning Only one male pairs with the female intense male competition inherent in group spawning. The absence of breeding behavior from any of the breeders often results in spawning failure Several factors like body size, pigmentation, age, and social dominance, environmental conditions, mating history, female reproductive state, male dominance and aggression are known to affect the mating behavior of fishes in many species

27. Courtship behaviour

28. NATURAL SPAWNING In Channa striatus , Construct a nest with its tail at the edge of tanks, bites off weeds which grows in them The species generally lays its eggs in shallow margins of weed infested waters where the weeds are cleared in a small circular area, probably during active spawning movement of the breeders weeds help to hold the floating eggs together without dispersal. Also found to breed in weed free waters and even puddles

29. Both parents guard the egg and larvae fertilization external Fry move in shoals near the water margin Parental care ceases when they attain a size of 57mm- young ones disperse fry and fingerlings frequent the surface and column juveniles are column and shallow bottom dwellers.

30. FECUNDITY few hundreds to a few thousands, depending on the size of the fish vary between 2200 and 34,000 among cultivated murrels Fecundity differs in different agro climatic region as well as habitat eggs are free floating, spherical and non-adhesive and have an oil globule. Are golden yellow in colour in fresh condition

31. Fertilized eggs

32. INDUCED SPAWNING Hypophysation ,- natural and synthetic hormones using carp pituitary glands injected intramuscularly in the dorsolateral region in two instalments An initial dose of gland varying from 2 to 20 mg/ kg weight of fish was administered to the female Nil to 20 mg to the males After 4 to 6 hr a higher dose ranging from 5 to 380 mg/kg was given to the females and 5 to 250mg to the males Disadvantage- gonadotropic potency of pituitary glands used is unknown and difficult to standardise

33. Ovaprim hormone Single dosage Mass induced breeding Brood stocks were injected with dosage of 0.5 ml/kg body weight spawning occurred within 24-26 h, following the injection with the hormon Human Chorionic Gonodotrophin (HCG) and LHRHa also used for induced spawning

34. HORMONAL INJECTION

35. LARVAL REARING Captive reproduction and larval rearing of snakehead have been accomplished experimentally, but are not done on a commercial scale The hatchling, according to Alikunhi (1953), measures 4.33 mm in length. The yolksac is fully absorbed on the third day At this stage the post-larva has a well formed mouth and has commenced feeding Pronounced cannibalism is observed during fry and juvenile stages( minimised in captive stocks by ensuring abundant supply of preferred food

36. The life cycle of any species of fish from hatchlings to fry/fingerlings stage have high mortality Early fry subsists mainly on zooplankton , it is better to feed them with small plankton like rotifers and Artemia nauplii Fingerlings – insect larvae, fish fry, zooplankton

37. fed with a supplementary feed comprising of fish meal (50%) and mustard oilcake (50) at the rate of 5-8% of theestimated body weight.

38. REFERENCE Aquaculture Principles and practices. - T.V.R.Pillai Murrels and Murrel Culture - N.M.Chakrabarty

39. PAPERS Induced spawning of the striped murrel Channa striatas using pituitary extracts, human chorionic gonadotropin , luteinizing hormone releasing hormone analogue, and ovaprim - Mohamed A. Haniffa , Thangarose Merlin, Junaith Shaik Mohamed; Acta Icht. Piscat. 30 (1): 53-60, Ann. 2000 Effect of Different Synthetic Hormones and/or Their Analogues on Induced Spawning in Channa marulius - Muhammad Hafeez-ur-Rehman,1 Muhammad Ashraf , 1 Farzana Abbas , 1 Khalid Javed Iqbal , Iftikhar Ahmed Qureshi and Syedah Andleeb ; Pakistan J. Zool., vol. 47(3), pp. 745-752, 2015.

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