6(Z),9(Z),12(Z),15(Z),18(Z),21(Z)-Tetracosahexaenoic acid is a very long chain polyunsaturated fatty acid (VLCPUFA) that has been found in tunny, herring, cod-liver, pilot whale, sardine, and squalus-suclii-liver oils, bovine retina, and as a component of triglycerides and cholesterol esters in mouse and rat testis