Preliminary study on performance of triploid Thai silver barb, Puntius gonionotus

The triploid chromosome condition was induced in Thai silver barb (Puntius gonionotus) by application of cold shock (2 degrees C) to eggs at time inte rvals after activation of 0.5 min with a duration of 10 min which resulted in mean triploidy yield of 72.5% at 9 months of age. Growth rate of the 2-9 -month-old, cold shock group (0.1-6.2 g/month) did not differ from that of the control (0.1-5.7 g/month). Gonadal somatic indices (GSI) of presumed tr iploid males and females were lower than that of control (GSI values of the presumed triploids were 35.0-60.2% and 28.7-75.9% of control males and fem ales, respectively). Spermatogenesis and oogenesis were retarded in triploi ds. However, all stages of spermatogenic cells were observed in triploid ma les, including few spermatozoa. Oocytes of triploid females did not undergo vitellogenesis while normal oogenesis was observed in diploids. Nuclear vo lume of red blood cells (RBCs) of triploid fish was 1.63 times larger than that of diploids. (C) 2000 Elsevier Science B.V. All rights reserved.