Effect Of Feed Type On Growth And Fertility In Ornamental Fish, Xiphophorus Helleri

Abstract

The effects of feed type on feed intake and conversion, ovary weight, and fertility were studied in red swordtail, Xiphophorus helleri, for 235 days. Five groups of 30-day-old juveniles (0.05±0.001g; 16.84±1.59 mm) were fed Artemia, earthworms, liver, pelleted feed, or a mixed diet. Mean body length and weight were higher in fish that consumed the mixed diet or Artemia than in those that consumed the other diets. Pelleted feed produced the highest feeding rate but the poorest conversion rate. Fish fed pelleted feed consumed 143 mg/g/day, which was con- verted into 13 mg/g/day flesh. Those fed the Artemia, earthworm, liver, or mixed diets consumed 46, 56, 89, and 84 mg/g/day, repectively, which were converted into 16, 18, 21, and 24 mg/g/day, respectively. The conversion rate dropped after parturition, possibly due to allocation of a major portion of the feed energy to development of gonads and young. Irrespective of feed type, gonads appeared on day 42. On day 84, the gonad weight of fish fed earthworms was 16 mg (wet weight), significantly (p<0.01) increasing to 25 mg in fish fed Artemia, 31 mg in fish fed liver, 86 mg for pellets, and 145 mg for the mixed diet. A similar trend was noted in the gonadosomatic index. Females fed the mixed diet, Artemia, and liver released 753, 612, and 509 fry in four breeding cycles while those fed earthworms and pellets bred only three times, releasing 315 and 155 fry, respectively.