Food availability as a possible determinant for initiation and termination of reproductive activity in the tropical damselfish Chrysiptera cyanea

The involvement of food availability and temperature in the reproductive success was examined in a tropical damselfish Chrysiptera cyanea. Fish undergoing active reproduction were reared with saturated feed (SF; 1.5-2.0% of body mass) and limited feed (LF; one-tenth of SF) under natural photoperiod and temperature. Reduction of food ration affected spawning frequency during the reproductive season and spawning occurred repeatedly only under SF condition. The LF resulted in significant decreases in condition factor (K), hepatosomatic index (HSI), and gonadosomatic index (GSI) within 15 days with disappearance of vitellogenic oocytes from the ovaries. When the LF-reared fish were re-fed with SF, their K, HSI and GSI increased and vitellogenic oocytes re-appeared within 30 days. When these two feeding levels were crossed with 20, 25 and 30 degrees C temperature regimes, the fish maintained better ovarian conditions at 25 degrees C than those at 20 and 30 degrees C, but not under LF conditions, suggesting that minimum and maximum temperatures in their habitat influence reproductive performance in fish. It is concluded that food availability is regarded as a regional factor in tropical monsoon environments and has an impact on reproductive success of tropical fish within suitable ranges in photoperiod and temperature conditions.