Nothobranchius eggersi

These tiny fish have large, broad fins, with the dorsal and anal fins shifted toward the tail, forming a fan-like shape. Their coloration is particularly striking. In the trade, varieties are commonly labeled as "red" or "blue", but both colours are always present in the pattern—one simply dominates. A close relative of Nothobranchius eggersi is Nothobranchius rachovi, another annual species from similar habitats. Professional breeders work to preserve the unique traits of each wild population. Commercial collections therefore use a far more detailed classification system than just two colour forms. You will often see codes like "TAN 05–43 Kigongo", where TAN denotes Tanzania, 05 is the year of collection (2005), and 43 Kigongo is a unique locality code. This tells you the fish are descendants of specimens caught in that specific place in that specific year. When keeping them, house only varieties with the same or very similar locality code, regardless of collection year, since fish from that area may have been collected in later seasons as well.

This species is found on the east coast of the African subequatorial zone, within Tanzania. The fish prefers lowland areas, especially swampy river floodplains. The region experiences alternating wet and dry seasons; during the dry period, shallow pools often dry up completely. Adult fish die, but they have already laid eggs that remain viable in the dried substrate and hatch when the rains return.

The short life cycle of these fish means regular breeding is essential to maintain the population, making long-term keeping with other species extremely difficult. Nothobranchius eggersi are best kept in a species tank.

Creating suitable conditions for these fish is straightforward. These tiny fish are comfortable in a tank of 50 litres or more, suitable for a pair. Decorate with groups of rooted and floating plants, positioned to leave enough open water for swimming. You will need filtration, lighting, heating, and aeration. Since they come from calm, still water, strong internal water flow is undesirable. The filter is the main source of flow, so diffuse its outlet with an obstacle such as glass, a large stone, or driftwood. The water should be moderately to highly hard, with a weakly alkaline pH. See the Water chemistry section for detailed pH and dGH information. Weekly maintenance consists of changing 10–15% of the water and periodically cleaning the tank walls and substrate of organic debris.

In the wild, these fish are carnivorous, eating mainly insects and small aquatic crustaceans. In captivity, their diet should likewise be mostly protein-based food. Offer live or frozen foods such as daphnia, brine shrimp, and small bloodworm. Dried food may be used only as a supplement. Feed 2–3 times daily, giving only as much as will be eaten in 5 minutes. Remove any leftover food from the tank.

Spawning is usually done in a separate container with peat or coconut fibres as substrate, where the female will lay her eggs. You need only a heater and light; nothing else is required. Place the pair in the spawning tank, gradually raise the temperature above 24°C, and lower the water level to mimic the start of the dry season and trigger spawning behaviour. Once the female has laid and the male has fertilized the eggs, return both fish to the main tank, gradually adjusting the temperature back first. Returning them to their normal conditions often extends their lifespan. Drain the spawning tank, remove the substrate with the eggs, and keep it in a dark, warm, but dry place at 21–25°C for several months (usually 3–4). After this period, submerge the substrate in water again, and fry will appear shortly after. They grow very quickly and soon can be moved to the main tank. Importantly, after each cycle you must introduce new males or females to maintain genetic diversity. Repeated inbreeding within a single generation leads to degeneration.

Because of their life cycle, Nothobranchius eggersi are highly sensitive to water quality and conditions. One of the most common problems is oodinium, to which fry are especially susceptible. Prevention includes maintaining cleanliness, regular water changes, and adding a small amount of salt to growing tanks. In adults, poor conditions often cause bacterial infections that destroy fins or damage skin. The risk of disease increases when water parameters drift or feeding is excessive.

When selecting fish, watch for activity and colour intensity. Healthy individuals should be mobile, with fins held tight to the body and no visible spots or film on the skin. Avoid specimens showing signs of starvation, sunken bellies, or damaged fins. Since this is a seasonal species, ask the seller about the fish's age, as their life span is severely limited. When purchasing, favour fish from reliable lines to avoid problems stemming from inbreeding, which damages the viability of the offspring.