Occurrence of spontaneously spermiating eels in captivity
Two spontaneously spermiating Japanese eels, Anguilla japonica, one reared in fresh water and the other in seawater were identified. The gonads of these eels revealed male germ cells in all stages of development, as well as a large number of oil droplet or early vitellogenic oocytes. Sperm from seawater reared fish had fertilizing capability as reflected in the production of hatched larvae. The larvae grew normally and some of them underwent metamorphosis into glass eel. Albeit rare, we have shown that eel under cultivation conditions could mature naturally and produce milt with fertilizing ability.