Effect of salinity, light intensity and tank size on larval survival rate of shoemaker rabbitfish Siganus sutor (Valenciennes, 1835)

Abstract

The hatching rate and larval survival of shoemaker rabbit fish Siganus sutor at different environmental conditions were surveyed in 2014. Adult and sub adult fishes were captured from coastal waters of Lavan Island , Hormozgan, Iran and were transported to Persian Gulf and Oman Sea Ecological Research Center, and reared until reproduction season. Induced spawning took place using HCG hormone (500IU/kg body weight), during April – May when the environmental temperature was about 26-28oC. Eggs were stocked at a density of 25 Eggs L-1 in different tank size (40, 300 and 2400 L, tanks) to obtain the effects of tank size on eggs hatching rate and survival of fish larvae. Three salinities (25, 30 and 37 ppt), and three light intensity (10000, 5000, and 2000 lux) were examined in 300L tanks and survival rates of larvae were assessed on days 3, 5, 7, 10, 15 and 20 of culturing period. There was no significant difference between hatching rate of S. sutor eggs, in various hatching tanks (p>0.05), but survival rates of larvae was significantly higher in 300 Land 2400 L tanks (p 0.05). The survival rate of larvae was significantly higher in 2000 lux intensity of light (p<0.05), Under intense light (5000 and 10000 lux), mortality of larvae increased.