Triploidy Induction in Stinging Catfish Heteropneustes fossilis Using Cold Shock

Abstract

A study was conducted to induce triploidy in newly fertilized eggs of H. fossilis using cold shock. The eggs were exposed at two temperature-regimes viz. 20C and 40C. Among the various combinations of temperature and duration tested, shock duration for 10 min at 20C applied 3 min after fertilization was the best; it induced triploidy up to 94 to 97% of the eggs and had the best hatching and survival percentage of the triploid larvae. The success of triploidy induction was determined by chromosome counting. Erythrocyte measurements from diploid and triploid individuals were compared to results of karyotyping which showed a significant increase (P < 0.05) in the erythrocyte nuclear major and minor axes, area and volume in triploids over those in diploids. The implications of the results for production of genetically sterile triploidy in stinging catfish are briefly discussed.