Bivagina tai

From Fish
Adult B. tai in the gills of a fish
A stained specimen of Bivagina tai

Bivagina tai is a monogenean parasite of the gills of many marine fishes.

Life cycle

Elongate body of the parasite is 3-4 mm long. The parasite attaches on the gill by 2 pairs of haptors at the posterior end. Right and left clamps are approximately the same size and the number is a total of 80-130. The hermaphroditic adult produces spindle-shaped eggs with threads at both sides. The eggs are not linked to each other.

Clinical signs

Parasite (a few mm) attaches on the gill filament. Heavily infected fish exhibits anorexia and emaciates. Heavily infected fish exhibits the anaemic gill. Some infected fish die by infection. Since this parasite is not infectious to human, it is harmless in food hygiene[1].


Adult parasites attaching the gill filament can be visually seen, while immature parasites are observed by flattened samples of the gill under the light microscope.

The infection has a seasonal fluctuation.


A bath treatment with a hydrogen peroxide solution can be used for control of the parasite.


  1. Ogawa, K. (1988) Occurrence of Bivagina tai (Monogenea: Mycrocotylidae) on the gills of cultured red sea bream Pagrus major. Nippon Suisan Gakkaishi 54:61-64