Study on reproductive biology of Pterygoplichthys disjunctivus (Weber, 1991)

In the Mekong Delta was carried out in An Giang, Dong Thap, Can Tho and Hau Giang province from April, 2013 to March, 2014. The length-weight relationship of P.disjunctivus was determined as the equation of W=0.0587*L^2.6682 (R²=0.9688; n=758) and the condition factor (CF) ranged from 3.08% to 7.2%; the result showed that CF was higher from April to September. Gonadosomatic Indexs (GSI) of males were lower than that of females and GSI of female was lowest in February (0.396%) and highest in June (7.98%). Meanwhile, Hepatosomatic Indexs (HSI) was changed inversely with GSI and ranged from 0.78 to 1.47%. The results also indicated that the diameter of eggs ranged from 1.8 to 2.2 mm and the largest diameter was also in June that is same time with the hightest GSI values. The results showed that the main spawning season of P.disjunctivus occurs from April to September; however this species breeds in all year round. The fecundity of P. disjunctivus ranged 252 to 5820 eggs/female and relative fecundity fluctuated from 2665 to 18092 eggs/kg of female. Length at first maturity (Lm) was 11.12 cm and 9.14 cm of female and male, respectively.

Keywords: Pterygoplichthys disjunctivus, Reproductive biology, Mekong Delta.