The stimulatory effects of long wavelengths of light on the ovarian development in the tropical damselfish, Chrysiptera cyanea

The sapphire devil, Chrysiptera cyanea, were reared for 45 days during the non-reproductive season (September) under LD14:10 at four different wavelengths produced by light emitting diodes (LEDs): red (peak at 627 nm), green (530 nm), blue (455 nm) and white (5000 K). Ovarian maturation occurred in fish exposed to red, green and blue light, but not to fish under either white or natural light (control group). Mean gonadosomatic index was higher (P < 0.05) in fish group reared under red light than those reared under other treatments. Moreover, the ovaries of all fish (10/10) reared under red LED light contained vitellogenic oocytes. By contrast, a few fish in the groups of green LED (4/10 individuals) and blue LED (2/10 individuals) contained vitellogenic oocytes in ovaries, while the fish in the white LED and control groups had oocytes at immature stages. These results indicate that the light wavelength influences ovarian development in the sapphire devil and the level of effectiveness was red light > green light > blue light. The present results demonstrate that in addition to photoperiod, light wavelength is important for induction of gonadal maturation of reef fishes and that LED becomes a useful tool for aquaculture. Since responsiveness to lighting environments may differ among species, it is necessary to define optimum photic conditions on a species by species basis, if an artificial induction of reproduction is conducted by lighting environment in fish.