Friday, 7 September 2012

Breeding of Climbing perch

Breeding of Climbing perch (Anabas testudineus)
Climbing perch (Anabas testudineus), which is a highly demanded food fish. It is an important air breathing fish, which can be considered for culture in the areas with low dissolved oxygen. It is also popular for their lean meat, which contain easily digestible protein and fat of very low melting point and many essential amino acids making them ideal food. In India there are two species of anabas available i.e. A. testudineus and A. oligolepis. The fish having less deep body, lower pectoral and shorter snout is A. oligolepis with 46 chromosomes numbers and the fish with more deep body, shorter pectorals and longer snout is A. testudineus with 48 chromosomes numbers. Now anabas is a threatened species due to over exploitation and conservation measure is very much needed. Induce mass breeding and culture of this species may be ensuring to sum the fish in nature. This fish has a tendency to walk away from the pond during rains. It can be cultured singly or in combination with magur (Clarius batrachus) and singhi (H. fossilis). It can also be grown in combination with carp fingerlings of over 10 cm sizes. This practice can be employed in order to utilize the insect fauna as well as in respect of the role of fish as a biological check on small insects in water. 

The adults of A. testudineus are solitary and aggressive. It can gain weight up to 52gm in one year. Maturity occurs at the age of one when the fishes reach a size of 10-12cm in total length. The sexual dimorphism in A. testudineus is more apparent during breeding season. The mature male acquires a reddish hue on the body, particularly on the pectoral and ventral fins. The female shows only a faint reddish colour. Further in the male a distinct diamond shaped black spot appears in the caudal peduncle. In the female this black spot is oblong and somewhat diffused. Moreover, the female is contrast to the male, has a prominently bulging abdomen. The ventral distance between the bases of the two pectoral fins in the female is significantly greater than the male. In the breeding season, the female exhibits a prominent bulge at the vent, resembling the genital papillae while in the male this structure is absent. Mature male oozed out white milt and mature female oozed out ova even at a gentle pressure at the abdomen during breeding season. 

In nature the eggs are scattered in open water at the onset of the rains without any nest. The male wraps itself in the female body, fertilizing the eggs as they are laid. Each time 200 colorless eggs are released until about 5000 numbers are laid. The fecundity varies from 5000-35000 numbers. The eggs rise to the surface and float. The eggs hatch in 24 hrs and the fry are about 2-3 mm long. They are free swimming within two days of hatching.In case of artificial breeding with pituitary or synthetic hormone, a single dose of injection for both the male and female spawning actively and courtship behavior starts after 6 hrs of injection. The water temperature to be maintained at 280 C + 10C. Fertilized eggs float in the surface of water. It takes 18-19 hrs for hatching after spawning and newly hatches larvae measures 1.9-2.0 mm in length without any movement. Yolk sac completely absorbs on third day after hatching and settles at the bottom. Egg custard, plankton and Artemia are supplied as artificial feed for those fries up to 20-25 days. The survivability varies from 70-75%

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