Hysterothylacium aduncum

Abstract

Hysterothylacium aduncum is a nematode parasite of fish with a worldwide distribution. It has a complex life cycle in aquatic, mainly marine, environments, involving a wide variety of invertebrates, in addition to fish. The presence of this parasite, particularly in the third larval stage (L3), in fish of commercial importance, represents not only an aesthetic problem (due to its size and, at times, abundance, it is visible to the naked eye in the visceral cavity of the fish) but also a sanitary problem which may result in significant financial losses. In addition to its effects on the health of the parasitized fish, ingestion of these larvae with the fish can affect human health, resulting in anisakiasis/anisakidosis or the appearance of allergic symptoms. Consequently, further studies of this parasite, now facilitated by the development of axenic culture methods, are required in order to reduce the economic and sanitary impact of the parasite. The method described in this chapter used L3 from the host fish as the inoculum. Following their isolation and axenization they were cultivated either individually or in groups, depending on intended use, until they attained the state of sexually mature adults. When both sexes were cultivated together, after fertilization, the females produced fertile eggs which developed to form L3 in their interior and, occasionally, to hatch.