Induction of triploidy in tawes, Puntius gonionotus Bleeker by cold shock and comparison of growth and other traits between diploid and triploid fish
1994
Worawut Koedprang
Triploid chromosome condition was induced in tawes (Puntius gonionotus) by application of cold shock (2 deg C) to eggs at different time intervals after insemination (0, 0.5, 1, 1.5 and 2 min) with varying durations (5, 10 and 15 min). Shock duration of 5 minutes affected neither hatching rate nor ploidy level. Shock durations of 10 and 15 minutes started 0-2 minutes after insemination resulting in equal rate of triploid fry (62.50-85.00 %) with different hatching success. Hatching rate was decreased when cold shock was applied later than 1 minute after insemination. Yield of triploid fish was highest when eggs of 0.5 minutes after insemination were subjected to cold shock with shock duration of 10 minutes, which resulted in triploid yield of 72.50 %. Growth rate of 2-9 months old triploid (-0.08-6.22 gram/month) did not differ from those of diploid (0.07-5.72 gram/month). GSI of triploid males and females was lower than that of the respective control (GSI values of triploids were 35.00-60.26 % and 28.76-75.90 % of diploid males and females respectively). Spermatogenesis and oogenesis were retarded in triploids. However, all stages of spermatogenic cells were observed in triploid males, including few spermatozoa. Oocytes of triploid females did not undergo vitellogenesis while normal oogenesis was observed in diploids. Nuclear volume of red blood cell of triploid was 1.63 times larger than that of diploid.
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