The giant danio (Devario aequipinnatus) is a tropical fish belonging to the minnow family Cyprinidae. Originating in Sri Lanka, Nepal, and the west coast of India, this species grows to a maximum length of 4 inches (10 cm), making it one of the largest of the danionins. It is characterized by a blue and yellow, torpedo-shaped body with gray and clear fins.
In the wild, giant danios live in clear streams and rivers among hills at elevations up to 1000 ft (300 m) above sea level. Their native substrate is small gravel. They are native to a tropical climate and prefer water with a 6-8 pH, a water hardness of 5.0-19.0 dGH, and a temperature range of 72-81°F (22-27°C). As surface dwellers, their diets consist predominantly of exogenous insects, but is also supplemented by worms and crustaceans.
In captivity, giant danios will usually accept most foods. They are a somewhat aggressive fish, and may bully other fish in community tanks. Giant danios appreciate water movement to simulate the motion of the rivers and fast-moving streams of their origins, and prefer to school.
Giant danios are also used as dither fish in South and Central American cichlid aquariums. The larger cichlids chase and defend their territories against the giant danios, which allows the cichlids to exhibit more natural behavior.
As egg-scatterers, danios produce around 300 eggs in a single spawning. They spawn in clumps of plants.
A so-called "golden giant danio", sometimes seen, is in reality a partial albino fish. Devario affinis, Devario browni, Devario malabaricus, and Devario strigillifer were originally deemed synonyms, but are now valid species.