Gastromyzon ocellatus

Gastromyzon ocellatus has a flattened body, adapted for life in fast-flowing waters. Its coloration is dark brown, with the dorsal side adorned with 7-8 creamy transverse bands, and vertical stripes along the sides of the body, often interrupted and forming a characteristic pattern of ocellated spots. The fins are oriented horizontally, forming a powerful suction disc. Adult specimens reach about 4.5 cm in length. Sexual dimorphism is observed in body shape: females are usually plumper, while males may have a wider head, and during the breeding season, noticeable tubercles often appear on their heads.

The species is endemic to the island of Borneo and exclusively inhabits the Sarawak River basin in Malaysia. In nature, it lives in shallow, fast-flowing streams with clear, oxygen-rich water. It prefers areas with a stony or gravel bottom, where a rich biofilm of algae and microorganisms develops on the surface of rocks and boulders. It is often found near waterfalls and rapids, where it stays in shaded areas, clinging to hard surfaces against the current.

A peaceful but territorial fish. Intraspecific conflicts usually arise over the best feeding spots, but they rarely result in injuries. In an aquarium, it is recommended to keep a group of 4 or more individuals to observe their interesting social behavior. They are well compatible with small, peaceful fish that live in similar conditions, such as danios, rasboras, or other types of river gobies that can withstand strong currents.

For keeping, an aquarium of at least 60 L is required with intensive filtration and aeration, providing a water flow rate 10-15 times the aquarium volume per hour. The aquascape should mimic a riverbed: plenty of smooth stones, pebbles, and driftwood. Lighting should be bright enough to stimulate algal growth on decorations. A tightly fitting lid is essential, as the fish can move along the glass above the water level. Parameters: temperature 20-24 °C, pH 6.0-7.5, hardness 2-12 dGH.

In nature, it primarily feeds on algal growth and microorganisms (periphyton). In aquarium conditions, it is necessary to ensure the presence of mature algae on rocks. The diet should be supplemented with high-quality dry foods for bottom-dwelling fish, spirulina tablets, and frozen foods such as brine shrimp or bloodworms. It is important to avoid an excess of protein-rich food to prevent digestive problems. Feeding should be varied, and food should be distributed across different areas of the bottom.

Breeding in captivity is difficult and rare. Spawning is paired, accompanied by complex courtship behavior ("dances" and synchronized swimming). Eggs are laid on hard surfaces, such as stones. Fry are very small and require a developed microflora in the aquarium for feeding during the first days of life. Successful breeding cases are usually associated with creating specific conditions: imitating a seasonal temperature increase followed by cooling and maintaining high water quality.

The species is sensitive to low oxygen levels and the accumulation of organic waste. Under poor keeping conditions, the fish quickly lose condition, become lethargic, and are prone to emaciation. Characteristic problems include edema, often associated with kidney dysfunction due to poor water quality or improper nutrition. Prevention involves maintaining high water purity, regular water changes, and providing a strong current that mimics their natural environment.

When purchasing, choose active fish that constantly move across surfaces and scrape for food. Avoid emaciated individuals with sunken bellies, as they are often extremely difficult to adapt to aquarium conditions. Before buying, make sure the fish shows interest in food and has no visible damage, growths, or signs of parasite infestation. It is advisable to acquire a group of individuals to reduce stress during adaptation to a new aquarium.