Captive breeding and seed production of Etroplus suratensis in controlled systems
2009
Padmakumar, K. G. | Bindu, L. | Manu, P. S.
Pearlspot, Etroplus suratensis, the largest indigenous cichlid, breeds in shallow, peripheral waters and are most critically exposed to human interferences in Vembanad lake, the home ground of this species. The species exhibit a complex courtship behaviour involving pairing and nesting. Captive breeding of E. suratensis was undertaken, in specially designed artificial raceway tank, with depth situations ranging from 30 to 80 cm. Paired fishes were stocked for breeding in raceways provided with artificial spawning surfaces and breeding pits to facilitate egg attachment and 'pit caring', characteristic of the species. A total of 50 trials were carried out and in over 75 % of the cases, nest were confined to shallow depths between 12 and 45cm. The mean number of eggs within a nest was observed to be 32 cm-². Almost round the year breeding was possible in this controlled system and the breeding success was as high as 71 %, much higher than that in the traditional earthen pond system (60%). The fertilization rate in the confined raceway system fluctuated between 82 to 100%. When eggs were incubated allowing parental care, hatching rate varied from 63 to 99 %. Hatching of eggs occurred in 70-72 hrs at 25-27°C. The hatched out larvae, were heavily yolked and were observed to become free swimming on the 6th day. The fry yield under the devised system is perceptibly high (61%), as compared to that in earthen ponds (28 %). The technique devised is a reliable system for large scale production of seeds of this species under controlled conditions.
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