Preface The rapid growth of aquaculture in recent has raised questions concerning its environmental sustainability. To minimize the potential threat for climate change, there is need to modernize the sector in a manner that is more responsible, sustainable, & transparent and should generate enhanced public and private confidence in aquaculture. Therefore future aquaculture should be targeted to produce more fish using less water or recycle the water through elimination of harmful effluent discharge using intensive farming practices in open as well in closed systems. Whereby closed-systems can rely on modern systems of re-circulatory aquaculture (RAS), biofloc Technology (BFT) and aquaponics; open systems of farming in ponds, cages and pens will require mechanical aeration and water quality management protocols for sustainable growth potential. Present day freshwater aquaculture is mainly carp centric, a low value fish and hence operating modern systems of farming with carps may not be able to substantiate outputs. Further, carps are not suitable to grow in small enclosures due to growth problems. In order to effectively use these systems, the focus now should be on aquaculture of high value species, which can sustain intensive stocking with minimum disease risk. Striped murrel or striped murrel or chevron murrel (Scientific name, Channa striata) is an important species of many countries of South-east Asia including India. It is popular for its esteemed taste, therapeutic values, antinociceptive properties and hence consumed by many to induce healing and pain control after clinical operations. It contains high arachidonic acid (AA), which is a precursor of prostaglandin that may initiate blood clotting and enhance tissue growth. It is devoid of muscular spines and hence easily processed for making fillets for meeting the export demand. The species is air-breathing and can live without water for few hours and with little water for several hours, hence suitable for marketing in live condition to nearby and far places. In comparison to carps, the growth of this species is better in small rearing enclosures and hence farmers having small landholdings and entrepreneurs who wish to adopt intensive farming under indoor conditions, can make great use of this high value farming species. The efforts made in the past on farming of this species has not shown promising results due to several problems associated with its breeding, seed production, larval rearing, grow-out production and non-availability of species and size-specific artificial feeds. However major handicaps are now being understood with recent global research and it has become possible to overcome them to a larger extent. Therefore efforts have been made to compile the outcome of available research with personal research experience of the authors to provide updated information on this important valuable species for the promotion of aquaculture in respect of reproductive biology, breeding, larval rearing, cannibalism mitigation issues, fingerling rearing and grow-out productions under different farming system.

The species is commonly found in tanks, ponds, lakes, reservoirs, canals, swamps, etc in freshwater plains. It is air-breathing in nature and survives easily low oxygen stress. During drying-up of water bodies in summers, it has been reported to penetrate deep under moist-earth and come out live on arrival of rains. The name 'murrel' encompasses its resemblance to reptile (snake) due to presence of body scales all over its body including head region. Fully-grown adults are dark greenish brown with faint black and white vertical bands visible across its entire abdominal length below the lateral line and a black ocellus at posterior end of dorsal fin. Striped murrel is one of the important food fish of high commercial value due to preference for its meat quality, therapeutic and antinociceptive properties and hence consumed by many to induce healing and pain control after clinical operations. It contains high arachidonic acid (AA), which is a precursor of prostaglandin that may initiate blood clotting and enhance tissue growth. Geographically, the species is distributed in Western to Southeast Asia including Bangladesh, Cambodia, China, India, Indonesia, Lao People’s Democratic Republic, Malaysia, Myanmar, Nepal, Pakistan, SriLanka, Thailand and Vietnam (Chaudhary, 2019). It is supposed to be introduced in countries like Fiji, New Caledonia (Welcomme, 1988), Madagascar (Stiassny and Raminosoa, 1994) and Hawaii (Courtenay et al., 2004). The species has been reported to grow to a length of 100 cm (Rahman, 1989) and categorized„ Least Concern under the IUCN Red List (IUCN, 2020). Globally, 92523 ton of striped murrel is produced (FAO, 2016), of which the major share of 70802 ton is contributed from capture fisheries and 21721 ton from aquaculture (Figure 1). Though capture fisheries of striped murrel is quite stable in terms of global production, the aquaculture has shown a steady rise in last two decades. In India, though no production data is available, the production of this species is mainly contributed from the capture fisheries with meager contribution from aquaculture. This has caused serious stress in past few years on its resources, more particularly due to habitat degradation and man-made hazards in aquatic ecosystem.

Knowledge on fish reproductive biology is extremely important to understand various issues relating to reproduction and fishery management. Reproductive success in aquaculture systems depends to a greater extent on our knowledge about sexual differentiation, gonad structure, gametogenesis, spawning, larval metamorphosis, etc for successful captive breeding of a fish species. This chapter therefore, contains information on secondary sexual characters, sex-ratio, gonad structure, gonadal maturity, fecundity and embryonic development of striped murrel. 2.1 Secondary Sexual Characters The sexes are separate in striped murrel however differentiation of sex is not easy when fish is immature. The differentiations in sexes become distinct with advancement of maturity during spawning season. On attaining full maturity, a good fecund mature female could be easily distinguished with having bulged belly originating nearing the site of pectoral fins and extends near to the vent.

3.1 Spawning Season Striped murrel breeds in stagnant waters and commence breeding in ditches, ponds, tanks, flooded paddy fields, wetlands and dead end of rivers; a little prior to or with the onset of monsoons (Bhattacharya 1946; Chacko 1947). Striped murrel is a batch spawner species and hence breeds several times in a year. According to Courtenay et al. (2004), spawning occurs in this species all through the year. In northern states of India, the breeding season of this species coincides with south-west monsoon and extends from June to September with peak in mid of June to mid of August (Qasim and Qayyum, 1961). However, the species has been reported to breed during November to January in southern India (Alikunhi, 1953).

In order to get assured supply of quality seed weaned on formulated diet, the captive spawning is the right choice for successful farming of striped murrel. Captive spawning involves several activities such as broodstock development, induced breeding, hatching of eggs, larval rearing, etc. These activities are given in detail in the following sections. 4.1 Broodstock Development Brood stock development is an integral part of captive breeding programme in fish and the success of breeding largely depend on it. It involves rearing of healthy brooders of both sexes in captive conditions to meet the targeted production of seed. In striped murrel, maturation of gonad begins in the first year of their life. However, brooders of 2+ year age or above are better and recommended for captive breeding (Pati et al., 2004). A size of 400g to 1500g is considered ideal (Fig. 10). Brooders may be procured from wild sources or reared on-farm from farm-raised fingerling. Brooders from wild stocks are to be procured at least 2-3 months prior to spawning season so that they acclimatize to the farm conditions. It is recommended to give them a bath of 50 ppm formalin for about 8 hours under vigorous aeration before stocking in the tank/pond. Formalin treatment removes external pathogens from the fish body. Brooders raised at the same farm do not require formalin treatment, if they are free from any wound.

Predation and cannibalism are entirely two different processes. In predation, the animal used to consume other species then their own, whereas cannibalism is a practice of eating one’s own kind. Cannibalism is a common behavior in animal kingdom and has been recorded in more than 1500 species. It is reported in an increasing number of fish species belonging to group/ families such as air-breathing catfishes (Clariidae), pikes (Esocidae), percids (Percidae), characids (Characidae), latids (Latidae), gadids (Gadidae) and in over 30 other families, including cyprinids (Cyprinidae) and salmonids (Salmonidae) (Smith & Reay, 1991; Hecht & Peinaar, 1993; Folkvord, 1991; Baras, 1998; Qin et al., 2004). Cannibalism is a common ecological interaction and depends on genetics and fish behavior; mediated by appetite and metabolism and is promoted by size differences, and is more intense among fast growing larvae and young juveniles than among older fish (Hecht and Pienaar, 1993; Baras, 1998). Cannibalism is a serious problem in the farming of striped murrel that starts from the early larval stage (Ng and Lim, 1990) and continues at all sizes including during parenting also. Murrels have large mouth gape; sharp jaw teeth for catching & grasping prey and can consume prey fish more than half to two-third of its length (Wee, 1981; Diana et al., 1985; Ng and Lim, 1990 and Qin and Fast, 1996). Its aerodynamic body shape allows fast movement in water and catching the prey with ease. Striped murrel observes two types of cannibalism, Filial and Intracohort, which is discussed in detail in the subsequent sections.

The objective of larval rearing is to mass-produce high-quality and healthy juvenile fish. In larval rearing, the management of both rearing environment and feeding regime are the most important aspects. Improving larval rearing technique requires understanding of larval morphology & behaviour and requirements of live food, artificial diet and environmental conditions at different ages of larvae (Liao et al., 2001). Striped murrel is predatory as well cannibalistic species in nature. Therefore understanding about its behavior with respect to feeds and feeding, stocking density with growing age is utmost important. It is a general thinking that fish hatchlings do not require exogenous food until yolk-sac attached to their body is exhausted. But this is untrue with many carnivorous fish species, particularly those observe cannibalism. Larvae of such fish species start feeding much before the yolk-sac absorption; rather delay in getting feed make them weak or force them to feed on the conspecifics. Therefore in order to understand larval behavior of this species in respect of feeds and feeding, knowledge on its ontogenic development is crucial particularly in respect of age at which mouth opens; mouth gape size, food choice, size of food particle at different age-groups and finally the age when gut digestion starts. Yulintine et al. (2017) have given ontogenetic details of striped murrel larvae since hatching. According to him, mouth opens and exogenous feeding begin in this species when hatchling grows to a size 4.63+0.25mm on second say of hatching. On day-3 after hatching, the buccopharynx channeled with the anterior intestine through a short oesophagus and rather narrow lumen, with having prominent liver developed by this time. Two pyloric caeca appeared on day-25 hph, indicating the transition from larval to juvenile stage and acquisition of an adult type of digestion. This chapter provides strategy for larval rearing of striped murrel based on ontogenic studies and work carried out by various workers in this field including that of authors.

Stocking fingerlings in grow-out ponds increases survival rates, cut-down culture duration, better feed management and reduce risk-factors on account of natural as well disease occurrence. In pond culture, good amount of fry-size seed suffer predation from enemies such as snakes, birds and predator fishes, if any and mortalities due to disease occurrence as smaller size fish is more vulnerable. However, fingerling stocking reduces predation loss to a greater extent, increase survivals, allow better feed management and highe production. This is truer with carnivorous fishes and particularly those observe cannibalism. Qin and Fast (1996) stated that the rate of cannibalism is higher in small size (TL) predators than the larger in case of striped murrel, so stocking large size fingerling in culture ponds reduces chances of ICC and hence recommended for grow-out production. 7.1 Traditional Methods of Fingerling Rearing Wee (1981) has defined traditional system of murrel farming in Thailand in which seed of murrel was procured from wild resources and raised to large fingerling size before stocking. Two type of practices being used to raise fingerlings. In the first one, the pond(s) designated for fingerling production are stocked with brooders of SFs so they could spawn in the stocking pond(s) few days before the stocking of striped murrel fry and could directly feed upon the juvenile SFs. In second system, the fingerlings were reared to accept small-size fish (SF) along with rice bran to cut down cost of feeding on production of fingerling. In recent, more systematic approaches have been made to wean the seed collected from the wild resources on inert diets totally. The protocol adopted for weaning the fingerling on inert diet includes initial feeding with cut pieces of SFs and then gradual supplementation of inert diet till fingerlings start relishing inert diet completely.

The farming of striped murrel is quite old in many south-eastern and south Asian countries including India under traditional farming system. Wee (1981) has given an account of traditional farming of striped murrel in Thailand, where seed of wild stock was stocked in very high density (75-460 numbers/m2) in ponds. Freshwater small fish (FSF) were fed to the seed during pre-monsoon and monsoon seasons and subsequently marine small fish (MSF) mixed with rice bran to satiation level. The fish grew to 700-1000 g in 7-10 months with an FCR of 6.5:1 and production of 9.0-15.6 kg/m2. In another culture trial, Diana et al. (1985) have described a poor survival of 9-13%, when they stocked seed @ 40-80 number/m2 collected from wild sources and fed them on FSF for 9-11 months. There are records of backyard production of this species also (Wan et al., 1992). The major problems with traditional farming were poor & uncertain survivals, problems of getting SFs and occurrence of diseases due to poor management protocols. Therefore for a scientific farming of this species, the major bottlenecks are the non- availability of hatchery seed, species & size specific feed, cannibalism at all stages and disease occurrence. These bottlenecks have been addressed to a greater extent by the researchers in recent and protocols for hatchery seed production and cannibalism reduction have been simplified to a greater extent with the availability of commercial pellet diets to boost its farming. Vietnam has been pioneer in the production of farmed striped murrel in recent, following new initiatives and based on its success, neighbouring countries such as Indonesia, Camobodia, Thailand, Myanmar, etc have also taken initiatives to boost production of this high value species in their countries.

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