Hermaphroditic fish

Lin, H.C. and W.A. Dunson. 1993. The effect of salinity on the acute toxicity of cadmium to the tropical, estuarine, hermaphroditic fish, Rivulus marmoratus a comparison of Cd, Cu, and Zn tolerance with Fundulus heteroclitus. Arch. Environ. Contam. Toxicol. 25 41-47. 

Tanaka, J.N. and J.M. Grizzle. Effects of nonylphenol on the gonadal differentiation of the hermaphroditic fish. Rivulus marmoratus. Aquat. Toxicol. 57 117-125, 2002. 

Female sexual development and behaviour in mammals occurs by default and requires no ovarian secretion, and it is only in genetic males that the testis can secrete hormones which destroy this female pattern and superimpose that of the male. Sexual differentiation is not so well defined in fish, and larval exposure to both synthetic estrogens and androgens is widely used in aquaculture to produce monosex cultures. Endocrine disruption of sexual differentiation in fish may therefore reflect both the complexity and diversity of such processes between different species. Some care is required in use of the terms hermaphrodite and sex-reversal since a true hermaphrodite has both functional testes and ovaries and a sex-reversed fish is fully functional as its final sex—both produce the appropriate viable gametes. Such functional sex-reversal is not possible in mammals, but in some species of fish it is the normal developmental pattern. In most of the cases of hermaphroditism or sex-reversal reported in the non-scientific press, there is evidence only for a few ovarian follicles within a functional testis. This may be considered as feminisation or a form of intersex, and is very clearly endocrine disruption, but it is certainly neither sex-reversal nor hermaphroditism. In some cases the terms have even been used to infer induction of a single female characteristic such as production of yolk-protein by males. 

The negative effects of TBT have been observed in the bivalve larval development of Crassostrea gigas, Mylilus edulisf Venus gallina, Spams aurata, in Nassarius reticulate and in the hermaphroditic snails Phisa fontinalis and Adelomelon brasiliana Since TBT exerts a variety of toxic actions on some mollusks and fishes , an adverse effect of TBT on human health is a real threat. ... 

Warner, R. R., 1984, Mating behavior and hermaphroditism in coral reef fishes. Am. Sci. 72 128-136. 

Certainly the idea of equilibrium has been applied to populations of a particular species generally. Some species exhibit sequential hermaphroditism. In these species, such as many species of coral reef fishes, sex change is a normal anatomical process. Clownfish, wrasses, moray eels, gobies and other fish species are known to change sex, including reproductive functions. A school of clownfish is always built into a hierarchy with a female fish at the top (Figure 17.6). When she dies. 

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