Kuhli loach

The Kuhli loach, Pangio kuhlii, is a small worm-like freshwater fish belonging to the loach family (Cobitidae). It originates in Indonesia and the Malay Peninsula.

Physical description

The Kuhli loach is an eel-shaped fish, elongated with slightly compressed sides, and very small fins. The dorsal fin starts behind the middle of the body, and the anal fin well behind this. The eyes are covered with a transparent skin. The body has 15 to 20 dark brown to black vertical bars, and the gaps between them are salmon pink to yellowish with a light underside. When the fish are not actively breeding, there is no known way to distinguish between males and females. When breeding, the females often become monstrously fat before spawning. Spawning is not easy, but when it occurs a few hundred greenish eggs are laid among the roots of floating plants. Maximum size is 4 in (10 cm) long, and they have four pairs of barbels about their mouth.

Habitat, diet, and related information

The natural habitat of the Kuhli loach is the sandy beds of slow-moving rivers and clean mountain streams. They are a social fish and are typically found in small clusters (they are not schooling fish but enjoy the company of their species), but are cautious and nocturnal by nature and swim near the bottom where they feed around obstacles. They natively live in a tropical climate and prefer water with a 5.5 – 6.5 pH, a water hardness of 5.0 dGH, and a temperature range of 75 – 86 °F (24 – 30 °C).

Other noteworthy information

In the wild, the fish spawn communally in very shallow water. The Kuhli loach is a bottom dweller which burrows into soft places. Its ordinal name ‘Acanthophthalmus’ comes from the meaning ‘thorn’ or ‘prickle-eye’, after a spine beneath each eye.

Etymology of name

The Kuhli loach was originally described as Cobitis kuhlii by Achille Valenciennes in 1846. The fish is also commonly called Coolie loach, Giant Coolie loach, Slimy loach, and Leopard loach. In scientific literature, it has been referred to as Acanthophthalmus kuhlii. The genus name Acanthophthalmus is a junior synonym of Pangio.

In the aquarium

The Kuhli loach is commonly kept as a pet in tropical aquaria. There are a number of species of the genus Pangio that appear similar and are sold under the same name, require similar care, and are all excellently suited for household tanks. They tend to be hardy and long-lived in the aquarium and get along well with their own kind as well as others.

In an aquarium environment, especially if the gravel is suitably finely grained, Pangio species can burrow into the bottom and there remain unseen for long periods of time, emerging to eat during the night. If the gravel is later disturbed, a hobbyist might well find themselves faced with fish assumed lost a long time ago.