Nannostomus minimus

Adults of this species reach a length of approximately 2 centimeters. Sexual dimorphism is weakly expressed: males and females have only minor external differences. The main body color is grayish-brown, with red pigmentation on the belly, as well as at the base of the dorsal and caudal fins.

Its natural habitat is in South America, in the Essequibo River basin, located in Guyana. Nannostomus minimus prefers small tributaries, streams, and swampy areas. These places are characterized by very slow current or its complete absence, an abundance of dense aquatic vegetation, and a brown tint to the water caused by a high content of dissolved tannins, which are formed as a result of the decomposition of plant remains such as branches, tree roots, and fallen leaves.

This is a peaceful and rather shy fish that feels comfortable in the company of its own kind. It is recommended to keep a group of at least 10 individuals, as they become excessively timid in smaller numbers. Nannostomus minimus coexists well with other non-aggressive species of comparable size.

For a school of 10 fish, the minimum aquarium volume should be 40–50 liters. The decor should include a dark substrate, as well as many aquatic plants combined with various snags and other natural decorative elements. Dried leaves from certain tree species, placed on the substrate, can be an important addition. In addition to their decorative function, they contribute to creating water chemistry conditions similar to natural ones by releasing tannins during decomposition. These substances affect key hydrochemical parameters such as pH and dGH. Keeping Nannostomus minimus usually does not cause major difficulties, provided regular aquarium maintenance. In particular, it is necessary to weekly replace a portion of the water with fresh water, promptly remove organic waste such as food remnants and excrement, clean decorations and glass from plaque, and control the concentration of nitrogen cycle products (ammonia, nitrites, nitrates), preventing their accumulation.

Being an omnivorous species, these fish readily accept most common aquarium fish foods, if they are appropriately sized. These can include flakes, granules, or various mixtures. In addition, live or frozen foods, such as Daphnia and Artemia, can be included in their diet.

Under suitable conditions, spawning occurs frequently, and some fry may successfully develop to maturity. However, if the goal is targeted breeding, a more controlled approach will be required. In a home aquarium, there is no pronounced seasonal breeding. It is often observed that some females are ready to spawn, while others are not. Therefore, in large schools consisting of dozens of individuals, reproduction can occur continuously. The fish do not form a clutch but scatter their eggs among dense thickets of fine-leaved plants. To protect the eggs from being eaten by adult fish, any discovered eggs should be transferred to a separate tank with identical water parameters. The incubation period lasts 1–2 days. For initial feeding, fry require microscopic-sized food. Infusoria are an ideal option, but specialized powdered foods or suspensions for aquarium fish fry can also be used.

Health problems in these fish arise only in the presence of injuries or keeping in unsuitable conditions, which leads to a weakening of the immune system and the subsequent occurrence of various diseases. At the first signs of illness, it is necessary first to check the water parameters for exceeding permissible values or the presence of toxic substances (such as nitrites, nitrates, ammonia). If deviations are found, all indicators should be normalized, and then treatment should begin.

When purchasing, it should be noted that this species is rarely available for sale and is often supplied as bycatch with other fish. It is important to carefully inspect the condition of the individuals in the store: healthy fish should be active, have clean fins without signs of damage or film, and display natural schooling behavior for the species. Avoid purchasing fish that appear emaciated, apathetic, or have visible body deformities, as due to their small size, they are sensitive to stress and transport conditions. It is recommended to ask the seller how long the fish have been received to ensure their adaptation to aquarium conditions.