Blue-Eyed Catfish

This is indeed a large catfish, capable of reaching 80–90 cm in length, although such sizes are rarely seen in artificial aquarium conditions. The fish's coloration is predominantly dark, varying from deep black to dark gray depending on the lighting. A characteristic stripe, consisting of pointed bony plates, runs along each side. Sexual dimorphism is weakly expressed, making sex determination difficult.

Its natural habitat covers large river systems throughout the Amazon basin in South America. It can be found in the territories of modern states such as Ecuador, Colombia, Venezuela, Guyana, Peru, Bolivia, and Brazil.

This species is a peaceful giant, but it can pose a threat to small fish that can fit into its mouth. It is perfectly compatible with other large, non-aggressive species. Keeping them is possible both individually and in groups; intraspecific conflicts have not been observed among these fish.

Due to their enormous size, such fish are not often acquired by amateur aquarists. Their keeping requires an aquarium of an impressive volume — from 1700 L, as well as expensive equipment and significant construction work. The latter may include floor reinforcement, and the installation of sewage and water supply systems. The design and installation of such aquariums are usually carried out by specialized companies, which often also undertake subsequent maintenance. The owner will only need to feed their pets in a timely manner.

These catfishes consume everything they manage to find on the bottom. In their natural environment, their diet consists of crustaceans, insects, and their larvae, which they seek out by sifting through sandy substrate. In aquarium conditions, they will readily accept all common types of sinking foods (whether flakes, granules, or tablets) intended for aquarium fish. It is important to ensure a regular presence of vegetable supplements in their diet.

Breeding in a home aquarium, even the most spacious one, is practically impossible. Oxydoras niger are bred by professional breeders on specialized fish farms. Less often, individuals caught from the wild can be found for sale.

The main cause of most diseases in these fish is unsuitable keeping conditions and poor-quality nutrition. If initial symptoms are observed, it is first necessary to check water parameters and the concentration of dangerous substances such as ammonia, nitrites, and nitrates. If the indicators deviate from the norm, they should be brought back into order, and only then should treatment begin.

Acquiring this species requires a conscious approach due to the impressive size of an adult, reaching 90 cm. Young specimens are often sold in stores, which creates a risk of purchasing a fish for which the owner does not have suitable keeping conditions. Before purchasing, it is important to ensure a long-term plan for providing an aquarium of 1700 L or a tropical pond, as rehoming an overgrown aquarium catfish is extremely difficult. When choosing a healthy specimen, attention should be paid to the absence of skin damage and bony plates along the lateral line, clean fins, and no signs of emaciation. The fish should show activity during twilight hours, be attentive to its surroundings, and have no visible ulcers or film on its body.