Flagfish

The flagfish has an elongated body and rounded fins. In adult males, the dorsal and anal fins are larger and the coloration brighter than in females. The body pattern consists of alternating horizontal stripes in red-brown or red and silver or blue-green. There is a yellow tint behind the head on the back, and a dark round spot is often visible in the centre of the body.

This species is endemic to the Florida peninsula. It inhabits numerous shallow lakes, backwaters, swamps, and also ditches and agricultural water channels.

During the breeding season, males show marked territoriality and aggression towards each other. For this reason, to keep a pair in a tank of around 50 litres, it is best to give each male its own territory. However, in larger tanks of 100 litres and above, it is possible to form communities of several males, provided each has his own area. Caution is needed with other tank mates: small fish may become targets of aggression from male flagfish, and large but peaceful neighbours may also suffer. The best option is to keep these fish in a species tank or with certain catfish species.

A group requires a spacious tank of around 100 litres, though a pair can be kept in a tank from 50 litres. When decorating, pay particular attention to plants: include plenty of both rooted and floating types. The floating plants may cover almost the entire water surface. Hard-leaved plant species are preferable. The substrate is usually sand, and you can add driftwood and pieces of tree roots for décor. Flagfish adapt well to various water parameters and feel comfortable even in slightly brackish water, which in the wild often enters their habitats during typhoons and hurricanes. This trait greatly simplifies water preparation for the tank. Simply use ordinary tap water that has been left to stand for a couple of days to remove chlorine. The minimum equipment includes a filter, an air pump, a lighting system and a heater. The heater can be omitted if the room temperature does not drop below 20–22°C. Weekly maintenance involves partial water changes (10–20%) with fresh water. If needed, clean the substrate of organic debris (droppings, uneaten food, fallen plants) and wipe algae from the glass.

Although they prefer live meat foods such as bloodworm, daphnia and small worms, flagfish readily accept high-quality dry foods (granules, flakes) if they contain protein components. It is recommended to combine dry foods with live or frozen ones. Plant-based supplements are also essential, such as spirulina flakes or other algae. Feed 2–3 times a day; the amount should be such that it is consumed in a few minutes. Uneaten scraps must be removed to prevent water pollution.

A common misconception, found in some scientific literature, is that flagfish breed by making pit nests in the substrate and guarding their offspring. The reality is somewhat different. Spawning usually occurs in spring or late summer. At this time the male occupies a temporary territory, which he fiercely defends from rivals, and uses his bright coloration to attract females. A female that has chosen a partner deposits eggs on the leaves or stems of rooted plants, after which the male immediately fertilizes them. Parental care ends there. The eggs are left unattended. Often the parents eat their own offspring, so it is best to move them to a separate tank, for example a 3-litre container. The incubation period lasts from 7 to 14 days, depending on water temperature. The fry feed on brine shrimp nauplii, microworms and other micro-foods.

The flagfish has a robust immune system and, with basic care, is rarely prone to specific diseases. The main threat to health is incorrect diet, in which protein-rich food predominates over plant-based food, leading to obesity and metabolic disorders. The fish are also sensitive to water quality, so when organic waste accumulates and nitrate levels are high, bacterial infections may occur, manifesting as fin damage or clouding of the mucous membranes. Prevention consists of weekly water changes and maintaining a stable temperature regime.

When buying, choose active individuals with clean fins and no visible damage on the body. A healthy fish should show natural curiosity and the characteristic jerky manner of movement. Avoid specimens showing signs of emaciation, a sunken belly, or fins that are unnaturally clamped to the body. Bear in mind that in shop conditions fish may be stressed, so it is worth observing their behaviour for a few minutes: healthy individuals should not show signs of lethargy or constantly hide in corners of the tank.