Peruvian Aphyolebias

Adults can reach lengths of up to 10 cm. They have a slender, streamlined body and prominent large fins, especially in males. Large eyes are a characteristic feature of the species, an adaptation to see in low-light conditions. The Peruvian Aphyolebias shows considerable variation within the species, so fish from different geographic areas may differ noticeably in colour. The predominant hues are usually grey-yellow and grey-turquoise. The brightest colours appear on the fins and tail. Regardless of colour variation, the body typically displays a striped pattern. In nature they live for just one season while their temporary habitat exists. In 7–8 months they rapidly complete their entire life cycle from egg to sexual maturity. In a home aquarium with stable conditions their lifespan increases noticeably, averaging 1.5 years.

This species originates in South America, with its natural range limited to Peru, as its name suggests. They inhabit northern Peru, living in small bodies of water in untouched tropical forests. These water bodies are typically shallow pools on the forest floor or backwaters near rivers with muddy bottoms covered in leaf litter and branches. The water is often turbid. These aquatic habitats are temporary: they form during the rainy season and dry out when the dry season begins. The fish's entire life cycle is tied to this seasonal cycle.

The Peruvian Aphyolebias usually occurs in groups of its own kind, reflecting the nature of its natural habitat. In the wild, coexistence with other species is rare; occasionally other killifish species may be found together. In a home aquarium, keeping them with fish of comparable size that can adapt to similar conditions is acceptable.

The minimum aquarium volume for 3–4 individuals starts at 40–50 litres. If breeding is not the goal, the décor can be quite simple. Use soft, dark substrate with a layer of leaves, branches and driftwood. Shade-loving plants may be added, as well as floating plants on the water surface. Equipment should include a simple air-lift filter and a heater. The Peruvian Aphyolebias prefers dimmed lighting. If the tank is in a living space, an additional light source is usually not necessary. It is essential to maintain low water hardness and acidic pH (around 5.3). The comfortable temperature range is quite high, between 27–30°C.

In nature this species is a predator feeding on small aquatic invertebrates. In an aquarium, the diet should consist mainly of live or frozen foods such as daphnia, bloodworm or glass worm. They can be trained to accept quality dry foods, but these should not form the basis of their diet. Feed once or twice daily in small portions.

Given their short lifespan, breeding can be a way to maintain their population in a home aquarium. Triggering spawning is usually not difficult even for beginners, but preserving the eggs and raising fry is more challenging. Fish reach sexual maturity at just 4–5 months and readily begin spawning. For best breeding results, provide a protein-rich diet. Live or frozen foods such as bloodworm, brine shrimp, daphnia or mosquito larvae are preferred. In nature they deposit eggs deep in soft substrate. When the water body dries, the eggs remain in the dried substrate until the end of the dry period. These conditions must be recreated in the aquarium. Therefore, substrate choice is crucial for breeding success. Use soft, fibrous materials, preferably natural ones such as coconut fibre or a layer of sphagnum moss. While waiting for spawning, clean the substrate regularly with a siphon, removing all organic debris. Once eggs are discovered, carefully remove the substrate. Rinse it gently with aquarium water, taking care not to damage the eggs and cleaning away as much debris as possible. Then dry the substrate to a 'slightly moist' state and place it in a container with a perforated lid. Keep this container in a dark place at around 25°C. The incubation period lasts 4 months. Periodically inspect the substrate for mould or fungi, removing affected eggs. Monitor moisture and dampen the substrate slightly if needed. After 4 months, submerge the substrate with eggs in water. If all conditions were met, fry will appear within several days.

No species-specific diseases have been described for this rivulid, but like other seasonal fish, the Peruvian Aphyolebias is highly sensitive to water quality and keeping conditions. Deviation from parameters, especially temperature fluctuations outside 27–30°C or accumulation of organic compounds, rapidly weakens immunity and leads to bacterial infections or fungal skin disease. Main risk factors include: — high levels of nitrates and ammonia, causing gill and skin damage; — sudden shifts in water chemistry, causing stress and secondary infections; — failure to quarantine new fish, increasing the risk of parasite introduction. Disease prevention is based on strict water parameter control and regular water changes. Given the species' difficulty in adapting to aquarium conditions, any signs of lethargy or refusal to feed require immediate checking of the environment.

When purchasing, choose active fish with no visible fin damage or signs of emaciation. In the shop, observe the fish's behaviour: healthy specimens show interest in their surroundings and display no apathy. Remember that this is an annual (seasonal) fish, so when buying it is important to ask the age of the specimens, as their lifespan in captivity is limited.