Acanthocobitis urophthalmus

Adults reach about 4 cm. The body is elongated and stretched, with rather short fins. The ventral and pectoral fins are used mainly for moving along the bottom or resting on it, not for active swimming. The mouth is surrounded by sensitive whisker-like antennae. The colouration is a combination of dark and light yellowish stripes, creating a tiger-like pattern.

The species is endemic to south-western Sri Lanka, where it inhabits mainly lowland rivers such as Kelani and Nilwala. The fish prefer shallow areas with fast flow and a bottom covered with pebbles, sand, or a mix of stones and organic debris. In their natural habitat, the water is highly saturated with oxygen.

Within the species, relationships are based on competition for territory. Although Acanthocobitis urophthalmus needs the presence of its own kind, they prefer to stay apart, each occupying its own small patch on the bottom. When space is limited, conflicts may occur. Toward other fish species they are peaceful. They get along well with most similarly sized tank mates. Excellent neighbours are species that inhabit the middle layer or the surface.

For a group of 3–4 individuals, the optimal aquarium volume starts at 50 litres. When setting up the tank, focus on the bottom layer. These fish like to dig in the substrate, so use sand, small stones, or aquarium soil. The bottom should have shelter for each fish: individual pieces of wood, coconut shells, dense plantings of rooted plants, or other natural and artificial elements. Water flow is recommended; usually no separate pump is needed, as an internal or external filter system provides both water purification and adequate circulation. Acanthocobitis urophthalmus prefers soft, slightly acidic water. For long-term well-being, keep the water chemistry stable and avoid sharp fluctuations in pH and dGH.

In nature, the diet consists of small invertebrates and detritus. In the aquarium they readily accept most popular sinking foods of appropriate size, including flakes and pellets.

Reliable reports of successful breeding in captivity are lacking. In nature the fish spawn in flowing water, but the specific conditions needed to trigger spawning in captivity have not been studied. Breeding attempts require conditions that closely mimic natural mountain streams with intense aeration and good filtration.

The species is sensitive to poor water quality and accumulation of organic waste, which often weakens immunity and leads to secondary bacterial or fungal infections. Signs of illness include loss of appetite, lethargy, coating on the body, rapid gill movement, or fin damage. Prevention consists of maintaining stable water parameters, regular water changes, and powerful filtration.

When selecting fish, pay attention to the following: — the fish is active and shows no signs of apathy — fins are intact and the body has no visible ulcers or spots — breathing is normal without rapid gill-cover movement — the fish is well-fed with no severely sunken sides. Note that this species often arrives in shops after transport, so check for stress behaviour and clean water in the seller's tank.