ABSTRACT
Sequential hermaphroditism is a common reproductive strategy that has evolved many times. Sex change from female to male or male to female is favoured, when sex specifi c reproductive success is differentially distributed with size/age. However, serial sex change characterized by changing between sexes more than once during the life of a fi sh may be expected with maximum sex specifi c reproductive success (Nakashima et al., 1995). It is to the credit of Kuwamura et al. (1994), who fi rst described the serial hermaphroditism or the ability to change sex more than once and in both directions from female to male and subsequently from male to female in the monogamous coral goby Paragobiodon echinocephalus; since then, serial hermaphroditism has also been confi rmed to occur in other monogamous gobies Gobiodon. micropus, G. aculolineatus, G. quinquestrigatus and G. rivulatus rivulatus, inhabiting Acropora corals from fi eld and aquarium experiments at Sesoko Island, Japan (Nakashima et al., 1996) and in Trimma okinamae (Sunobe and Nakazona, 1993). It is also known to occur in a cirrhitid hawkfi sh Cirrhitichthys aureus (Kobayashi and Suzuki, 1992) a pomocanthid Centropyge fi sheri (Hioki and Suzuki, 1996) and in the serranid Epinephelus akaara (Okumura, 2001). Controlling social conditions in captivity, Ohta et al. (2003) successfully induced bi-directional sex change in the Japanese wrasse Pseudolabrus sieboldi. The tendency and potency for serial hermaphroditism have also been shown to be in the gobies Lythrypnus spp (St. Mary, 1994, 1996), Gobiodon okinawae (Cole and Hoese, 2001) and humbug damselfi sh Dascyllus aruanus (Cole, 2002).
