The phospholipid composition and fatty acid characteristics of diacyl and plasmalogen forms of
phosphatidylcholine and phosphatidylethanolamine of sperm of five marine and five freshwater species
of fish have been determined. There was considerable variation in composition within each group of
fish, which obscured any differences which are related to the osmotic environment. Since such factors as temperature, nutrition, etc. probably greatly influence the lipid composition, we failed to determine a relationship between osmolality and phospholipid composition. We have also
found certain phospho-lipid peculiarities, characteristic of sperm of various species of fish.
Nevertheless, as we have found previously, the molar ratio of cholesterol to phospholipids in fish
sperm is determined by the salinity of the habitat.