Effect of water hardness on growth and reproductive potential inXiphophorus helleri and Betta splendens

摘要

Effects of water hardness (76, 316, 540 and 1018 CaCO sub(3) l super(-1)) on growth and reproductive potential were studied in aquarium fishes, red swordtail Xiphophorus helleri and fighting fish Betta splendens. X. helleri exhibited maximum growth parameters (mean body length and weight, rates of feeding and conversion and conversion efficiency) and reproductive performance in the highest hardness of 1018 mg CaCO sub(3) l super(-1). Female broods of red swordtail reared in 1018 mg CaCO sub(3) l super(-1) released 264 fry and it significantly (p<0.01) decreased to 211, 69 and 58 fry in fish reared in 540, 316 and 76 CaCO sub(3) l super(-1) respectively. On the contrary, B. splendens elicited better growth, feeding parameters and fecundity in the lowest hardness of 316 mg CaCO sub(3) l super(-1). Female B. splendens reared in 316 CaCO sub(3) l super(-1) laid more number of eggs/spawn (396) and yielded greater percentage of egg hatching (93%) than other groups. Although female brood laid more number of eggs/spawn, in egg hatchability drastically declined (2.15%) in fish reared in 1018 mg CaCO sub(3) l super(-1). X. helleri and B. splendens prefer hard and soft water respectively for maximum growth and reproductive performance.