Hypothalamic and Pituitary Abnormalities

Although it may appear obvious to compare fish sampled at clean and polluted 

It is also clear that it is difficult to relate cause and effect to any specific chemical since, with the exception of point source effluents, many waterways contain a multitude of chemicals, of which the active endocrine disruptor may not be that which has been measured in the water or tissue. For such reasons, many studies have used in vitro experiments in which isolated tissue, either from a control animal or one captured in a polluted water system, is exposed to a single pollutant in the laboratory. Such experiments have shown significant disruption to testicular activity by a wide range of xenobiotics, including cadmium, lindane, DDT, cythion, hexadrin and PCBs.  

Recent studies suggest that mercury can cause an instant decrease in the sperm viability of fish at concentrations comparable to those which are permitted in drinking water (1 /rg C ). The bioconcentration of the metal to levels in the testis considerably higher than this from water containing only 1/30 of permitted levels suggests that current legal limits are much too high. 

Courtship rituals in fish can involve a complex communication between males 

Ruiangwa, E Roelants, G. Eluyskens, M. Ebrahimi, D.E. Kime and E. Ollevier, J. Fish Biol., 

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