Etroplus- culture
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Etroplus the state fish of Kerala, India have great demand. the presentation deals with the aquaculture of etroplus
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Etroplus- culture
- 2. INTRODUCTION • known locally as ‘Karimeen’ • Largest among Indian cichlids • High-valued food fish • Endemic to peninsular India and Sri Lanka • Etroplus suratensis - brackish water fish • Naturally acclimatized to freshwaters • Ideal candidate for pond culture and most adapted for intensive farming • Lack of required quantities of fish seed -serious constraint • Exhibit Unique and prolonged parental care and biparental substrate breeding habit
- 3. Taxonomy • Kingdom-ANIMALIA • Phylum- CHORDATA • Class- ACTINOPTERYGII • Order- PERCIFORMES • Family- CICHLIDAE • Scientific Name:Etroplus suratensis • Common Name(s): Green Chromide, Pearlspot
- 4. Geographic Range • Etroplus suratensis is distributed in the coastal regions of peninsular India and SriLanka • In India-Kerala and Tamil Nadu. There are also populations in Goa, Andhra Pradesh, Orissa and West Bengal Biology • Elliptical black body with shiny white diamond like spots all over the body- 'pearl spot or'Karimeen’ • A mixed combination of green and black on its body. • Dark black stripes (usually 8 in number) are found from head to tail • Apart from the vegetative diet, they also feed on plankton, small worms and small prawns • Spirogyra -most favourite food • Fragilleria, Coscinodiscus -other major foods of karimeen • Fishes like catla and various carp species can be used for composite cultivation along with Karimeen
- 5. Use and Trade • popular foodfish. • Introduction to various other man-made habitats like tanks, ponds and dam reservoirs for culture and export. The most astonishing features of Karimeen, which makes it a candidate species, include the following: • 1. Ability to live in varying genre of water resources. • 2. Ability to make their living together with a wide variety of fishes, • 3. Lively growth rate and high survival rate of young ones. • 4. Delicious taste and flavor of karimeen. • 5. High survival rate of eggs, due to its ability of parental care. • 6. Consistent and stable market price Nutritive Value of Karimeen • Highly nutritive food • Good amount of meat • Fat, phosphorus, calcium, ash, iron and water. • Percentage : fat: 17.5 percent, phosphorus: 1.65 percent, calcium: 0.50 percent, ash: 1.08 percent, iron: 4.90 percent and water: 79.70 percent.
- 6. Seed Production • Seed-available throughout the year, along the east and south-west coasts of India • Peak season of abundance -May-July and November-February • Collection -brackish water and freshwater tanks and ponds • Simple method-twigs or branches are kept submerged in the water, a week ahead of day of collection • The juveniles congregating for feeding purpose are trapped using an encircling net or trap Pond Preparation • Draining • Removing all the materials that may be detrimental to the growth and productivity of fish farming. • Lime application when acidic
- 7. Drying • Accelerates the decomposition of organic matter • Provision of a better oxygen supply to bacteria • Better aeration • Kills disease organisms and their carriers • Drying period-two weeks • Acclimatization and Stocking of Breeders • Weight range-50-125 g • Stocked @ 5000/ha, after one week of fertilization of the pond • Disinfection by dipping In 1 per cent commercial formalin • Acclimatization • Sex ratio-1:1 • Additional breeders to compensate the natural mortality of breeders • Viable for three years Provision of Spawning Surfaces • Natural environment –Eggs are attached to submerged substrata like • Prepared pond- Palmyra leaves tied in bunches to fixed poles, coconut leaf petioles, coconut husks, bricks, pieces of asbestos sheets etc., have to be provided in the ponds
- 8. Water quality monitoring and management • Water level -1.2 meter • Water exchange 20 % to 30 % of pond volume per day through sluice gate operation & putting a filter net of 1-2 mm mesh size -successful practice and will not lead to escape of hatchlings and fry • As the fish grows, by increasing the mesh size of the filter net, the volume of water exchange and circulation in the pond increase, resulting in the maintenance of uniform water Quality Mechanical aeration • Essential for respiration, digestion and assimilation of food • Plenty of oxygen during day light & low level during night • Diffused air aerators employ an air blower and tubing to deliver air
- 9. Feeding • Initiated within 3-4 days after stocking. • Artificial feed prepared -groundnut oil cake 40 per cent, rice bran 45 per cent and fish meal 15 percent, fortified with vitamin and mineral mix @ 2.5 kg per 100 kg feed, is to be supplied daily @ 3-5 per cent of the fish biomass, either in Pelleted or in dough form. • Supplied in feeding trays kept at the bottom of the pond. The feeding trays should be examined daily and cleaned outside the Pond. • The quantity of the feed can be reduced whenever left-over feed is present in the trays, to avoid wastage and water pollution. • The presence of hatchlings indicates that the pond is to be manured with cow dung @ 500 kg/ha for the production of plankton, which forms the food for the hatchlings. • Small quantities o f the artificial feed (250-300 g/pond of 1000 m^) also can be broadcast in powder form during early morning
- 10. Breeding behavior & spawning • Breeding-pairing, nest making & parental care • Formation of schools of 15-20 members • Spawning pair formation • The most prominent indication of premating pair formation-conspicious intensification & darkening of colour pattern in males • In the case of females, black spotes & blotches appears on the ventral side between pelvic & anal fins, during spawning period • The breeding pair starts swimming along the side of the pond in search of a suitable substratum for nesting • Clearance of substratum by browsing them over • Stationary objects such as coconut leaves, coconut husk, stones, pvc hose pipes, bricks, coconut roots or any such hard solids as substrate • In the present trial bamboo stumps planted at close intervals were utilized as nest substrate
- 11. • Excitation of the female by hitting on the vent & nibbling on the abdomen & the pair swims around the chosen substratum • During ovulation the female lay flat on to the spawning site & gently move from one end to end and begin to attach eggs carefully with the help of its tubular, fleshy, cup like ovipositor • The female fish then glue their eggs by pressing closely on to the nest surface, one by one in a single layer, supported by their ventral fin • The male fish following close behind & rapid movements dashes over the freashly laid eggs, releases a spray of milt & fertilize them instantly. Duration of sperm motility is 3-4 minutes • Female repeat the process of egg extrusion on to the nest surface • The whole process of spawning is completed with in 45-60 min • Excavation of nursery pits ( thadam)-7-15 numbers with an average of 3-10cm in diameter & 2-7 cm in depth • Preferable breeding depth-15-44.5cm • Eggs are ovoid • The whole egg mass appears as patches
- 12. Pit nurseries Attached eggs collected from the experimental pond.
- 14. Hatching • Hatches out, generally in 70-72 hours • Hatchlings or ‘wrigglers’ are picked up by the brooding female in its mouth and are transferred to the breeding pits on the shallow pond bottom • ‘pit guarding’ -fanning of pits with their fins and render oxygenation of the hatchlings that are sheltered in the pits • Occasionally, a few wrigglers are picked up by the parents, rolled out in the mouth and returned and some times, the entire brood of wrigglers is shifted from pit to pit -helps to cleanse the sticky larvae by removing the adhering particulate matter. • As the yolk is fully utilized, within a week, the wrigglers develop their • Locomotor abilities and become free swimming and the larvae gradually move out of the pits, in schools and swim freely in to the open waters
- 15. Larval rearing • The early larval stage lasts for7 days during when the larvae develop into free- swimming individuals • During late larval stage-the tail remains long and the caudal fin is continuous • The larvae assume adult form within a month after hatching and measure about 18 mm • The young ones feed almost exclusively on zooplankton, the advanced fry on aquatic insect larvae, filamentous algae and other vegetable matter • The adult fish subsist mainly on filamentous algae, aquatic macro vegetation and plank tonic organisms. Worms, shrimps and insect larvae also form part of its food • Adult pearl spot can be fed with pelleted fish feed Embryonic Development • The eggs of E. suratensis, is elliptical in shape, with an average length of 2.2mm and width of 1mm. Eggs of Etroplus are pale yellow in color and after fertilization the color changes slowly and they become brownish just prior to hatching.
- 17. Larval And Post Larval Development Newly hatched larva • 4.5 mm in size. • The hatchling is characterized by large pigmented eyes and olfactory pits. • Mouth and jaws are not fully developed at this stage. • Anal opening is seen located 4-5 somites below the level of yolk sac. • Fin fold appear continuous from 3rd somite dorsally • head down and tail up with lashing movements and apparently exhibit positive geotaxis and a negative photo taxis. Hatchling – 2 day old • Average length -5.0 mm • Yolk sac that remain attached to the head region of the larvae become separated and the head appear free from the yolk mass • Otolith is clearly visible within the transparent body. • The two chambered heart located ventrally anterior to the globular yolk • Dorsal fin fold also appears continuous through the caudal end.
- 18. Hatchling – 3 day old • The larvae measures 6.0mm in length on the 3rd day. • Head region is well developed with the formation of a characteristic spout like mouth. • Yolk sac becomes reduced to half its size and heart appears spherical with rapid pulsation. • The transparent body becomes pigmented gradually. Hatchling – 4 day old • The larvae measures 6.0mm in length on day 4, starts gliding on the bottom and begins to swim up with yolk sac down • Pigmentation becomes remarkable on the head and trunk region. • Alimentary canal becomes visible through the body, marked by intermittent pulsative movements. Hatchling – 5 day old • The larva attains a length of 6.5mm on fifth day (Plate 18c). The yolk sac is greatly reduced at this time.
- 19. Hatchling – 6 day old • The larva measures 6.5mm and the yolk sac is almost resorbed by the 6th day. • Pectoral fins also begin to appear at this period • Operculum also becomes conspicuous and the gills become functional. • The fry become free swimming on the 6th day and move in shoals guided by the parents, swimming mostly underneath the parents. • The yolk gets fully resorbed by this time and the hatchlings attain an average size of 7-8 mm.
- 20. Captive Breeding of Etroplus Suratensis • As E. suratensis was observed to exhibit such a complex and unique courtship behavior, involving pairing, nesting and parental care, captive breeding of Etroplus suratensis was undertaken, in specially designed artificial raceway tank provided with simulated natural conditions. • The raceway system was devised as a trapezoidal tank with slopping sides and bottom. The tank facilitated appropriate and diverse depth situations ranging from 30 to 80 cm. • This system was provided with continuous water exchange that facilitated manipulation of the breeding environment in terms of temperature regime, turbidity, and a mild flow. • Artificial spawning surfaces, comprising 30-35cm long casuarina poles (25-87 nos.) fixed on specially fabricated cement concrete base were placed vertically in the tanks, approximately 50 cm away from the tank margin at varying depths. • Selected brood fishes, 70 pairs, of size 15cm (90g) to 23cm (250g) were placed in the raceway tanks, filled with filtered lake water. • In order to prevent formation of algal blooms and to avoid turbidity, the raceway tank was provided with adequate shading from above by using 50 percent shade netting.
- 21. Threats Wild populations of Etroplus suratensis are subject to various pressures brought on by people like habitat deterioration brought on by the disposal of solid and liquid wastes and the discharge of human fecal matter from adjacent habitations and an increasing number of tourism resorts and houseboats, which are going beyond the carrying capacity of the backwaters/estuaries. A major threat is from exotic species like Oreochromis mossambicus, Trichogaster trichopterus. There have also been reports in the past, of the Epizootic Ulcerative Syndrome (EUS) disease outbreak, which has been to have spread in South and south-east Asia since 1980.
- 22. CONCLUSION E. suratensis, a cichlid endemic to the region, is one of the most potential candidate species for aquaculture with immense commercial possibilities. Placement of brood stock in open ponds and pond spawning has been the only method of seed production of E. suratensis, followed for long. Investigations on captive breeding of this species under controlled conditions by manipulation of the breeding environment revealed that in this species, breeding is preceded by a very complex pair bonding. The major spawning season of E. suratensis is from February-April and June-October; the fish could be made to breed round the year under captive conditions. Nevertheless, in controlled breeding system also, maximum spawning success is achieved during June September. The spawning fecundity was quite high for fishes bred in tank breeding trials as compared natural system. This is apparently due to the better nutrition of the brood fish raised under captive conditions, as the number of eggs released per spawning naturally increases with body weight and physical well being of the fish.