ABSTRACT
Published studies on nitrogen metabolism and nitrogenous waste excretion in mudskippers centered around two mudskipper species: Periophthalmodon schlosseri and Boleophthalmus boddarti. Earlier studies on excretory nitrogen metabolism in mudskippers focused on comparing the rates of urea and ammonia excretion in fishes that were first held in water for a control period, followed with exposure to air for a set time, and then returned to water. The idea behind doing so was that the post-emersion excretion pattern would indicate changes in nitrogen metabolism taking place in the fish during terrestrial exposure. The more logical objective, however, should have been whether mudskippers possess a functional ornithine-urea cycle, and whether urea synthesis played a major role in detoxifying endogenous ammonia during terrestrial exposure, which requires a quantitative analysis of the nitrogen budget of the experimental fish.
