Discus Tetra

Adults grow up to 8–9 cm in length. This fish has a high body that is "compressed" laterally, resembling a disc in shape. The coloration is predominantly silvery, with the back having a darker shade. Sexual dimorphism is weakly expressed, and males are practically indistinguishable from females; females may appear larger immediately before spawning.

Its natural habitat is South America. This species is endemic and found in small river systems in Guyana and Suriname, preferring small rivers and streams that flow through tropical forests.

This is a peaceful and active fish, but its relatively large size (for Tetras) can intimidate smaller aquarium inhabitants. It is well compatible with other non-aggressive species and can be an excellent addition to a community of small characins, South American cichlids, cyprinids, catfishes, and others. It is recommended to keep these fish in a school of at least 8–10 individuals.

For a group of 8–10 fish, the recommended aquarium volume starts from 100–120 liters. The decor can be arbitrary, but it is desirable to recreate a natural environment with elements such as sandy substrate, stones, boulders of various sizes, driftwood, and aquatic plants. The Orbicular Tetra requires clean, flowing water with high oxygen content and moderate current. A productive filtration system will largely help ensure these conditions. In addition, water quality is affected by regular mandatory aquarium maintenance procedures. These include: weekly partial water changes (30% to 50% of the volume) with fresh water, timely removal of organic waste (e.g., food remnants and excrement), and monitoring of basic hydrochemical parameters and concentrations of nitrogen cycle products (including ammonia, nitrites, and nitrates).

As an omnivorous species, the Orbicular Tetra readily accepts various foods intended for aquarium fish. The daily diet can be formed from dry foods in the form of flakes or granules, supplemented with live or frozen artemia, daphnia, bloodworms, and other invertebrates.

This fish species does not exhibit developed parental instincts and does not care for its offspring, which leads to low fry survival rates. Nevertheless, this is compensated by the female's ability to lay a large number of eggs; for example, one adult can produce up to 2000 eggs. In artificial aquarium conditions, there is no seasonal breeding, so spawning is possible year-round. The fish scatter their eggs over the substrate quite haphazardly, not forming a localized clutch. The eggs are scattered across the bottom, with many remaining unfertilized. If breeding is planned, the eggs should be carefully transferred to a separate tank for their preservation. The incubation period lasts about 6 days. In the first days of life, the fry feed on their yolk sac, and then begin to swim freely in search of food.

Specific diseases that affect only this particular fish species have not been identified. When kept in suitable conditions, including high water quality, a balanced diet, and peaceful tank mates, health issues usually do not arise. The most common cause of illness is a deterioration of living conditions, which weakens the immune system and makes the fish susceptible to infections that are always present in their environment. Upon noticing initial signs of sickness (such as lethargy, emaciation, refusal to eat, or clamped fins), it is crucial to immediately check the basic water parameters. Often, restoring acceptable living conditions will lead to self-recovery, but if the fish is too weak or has suffered visible damage, medicinal treatment may be required. For more details on symptoms and treatment methods, consult the section “Diseases of Aquarium Fish.”

When choosing individuals in a store, pay attention to the fish's activity and the cleanliness of their skin. Healthy fish should be evenly distributed throughout the water column, show curiosity, and have no visible damage, spots, or signs of emaciation. Avoid buying fish that stay at the surface, breathe heavily, or show signs of apathy, as this may indicate poor keeping conditions or hidden diseases. Given that the species is schooling, purchase a group of 6–10 individuals at once to reduce stress during relocation and adaptation to a new aquarium.