Hemiodus

Hemiodus argenteus is a shoaling hemiodontid characin from Venezuela, Guyana, Suriname and Brazil, where it inhabits floodplain rivers and lakes. Like its congeners it can be very skittish when first introduced but usually settles over time, especially in a large group. Very active and growing to around 235 mm SL, it needs a large tank with a well-fitting cover, as it can leap surprising distances.

Hemiodus atranalis is a shoaling hemiodontid characin from Guyana, Peru and Brazil, found in floodplain rivers and lakes. Its reported maximum size is only 90 mm, though it probably grows bigger than this. Very active and skittish when first introduced, it usually settles in a large group, and the tank needs a well-fitting cover since it can leap surprising distances.

The slender hemiodus, Hemiodus gracilis, is a shoaling characin from Venezuela and Brazil, found in floodplain rivers and lakes. Probably the most often seen member of the genus in the hobby, it is sometimes sold as the red or red-tailed hemiodus. Very active and nervous when first introduced, it settles best in a large group in a spacious tank with a well-fitting cover.

Hemiodus orthonops is a large, shoaling hemiodontid characin from Brazil, Paraguay and Argentina, where it inhabits floodplain rivers and lakes. Growing to around 250 mm SL and very active, it needs a tank of at least 120 cm with a well-fitting cover. Like its congeners it can be nervous when first introduced but usually settles over time, especially in a large group.

Hemiodus ternetzi is a shoaling hemiodontid characin known only from the Rio Tocantins basin in Brazil. It can be identified by its black lateral stripe, which extends to behind the eye, and a dorsal fin with no pigmentation. Like other Hemiodus it can be skittish when first introduced but usually settles, especially in a large group.

Hemiodus unimaculatus is a large, shoaling hemiodontid characin from Guyana, Suriname, French Guiana and Brazil. It inhabits floodplain lakes and fast-moving parts of rivers and grows to around 215 mm SL. Somewhat flighty, it needs a spacious, well-covered tank and a large group to settle, and in nature it is known to spawn during the wet season.