Delicate Blue-eye

Adults reach about 4–5 cm in length. The most striking feature is the fish's blue eyes, which give it its common name. The body is yellowish with a silvery sheen, and the fins are short and translucent. Coloration varies depending on the population's origin. Sexual dimorphism is slight: males are a bit larger than females and have more elongated fins.

This fish is native to the northern coast of Australia, in a narrow coastal belt where tropical rainforest remnants border savannas. Its range extends from Darwin to Port Douglas on the Cape York Peninsula. Populations are also found on the islands of New Guinea and Aru. The delicate blue-eye inhabits river mouths and deltas that drain into the sea, as well as freshwater and brackish coastal waters, including tidal estuaries and salt marshes. It prefers still waters densely planted with aquatic vegetation.

This is a peaceful and active fish. Thanks to its ability to adapt to varied water conditions, the delicate blue-eye can live successfully with other fish of similar size and temperament. Keep it in a school of at least 8–10 individuals of both sexes.

A group of ten fish needs a tank of at least 80 litres. Arrange plenty of plants—both live and artificial—in clusters, leaving open swimming space. Include hiding places such as driftwood, roots or branches. The substrate can be anything, depending on your plants. Use dimmed lighting. Floating plants provide extra shade. Water clarity, oxygen content and stable chemistry are essential. Avoid sudden changes in temperature, pH or dGH. You can keep the delicate blue-eye in brackish water, but this is not necessary: fish from brackish habitats do perfectly well in fresh water, and vice versa.

It accepts any suitably sized food: dry floating pellets, live and frozen foods, with plant matter included. The best diet consists of small bloodworms, daphnia and brine shrimp.

Breeding is straightforward and needs no special preparation. Spawning can occur at any time. Raising the temperature to the upper limit (28–30°C) triggers spawning. Females lay eggs among plants; fine-leaved low-growing plants such as Java moss work best, as do artificial spawning substrates. Usually the dominant male fertilizes several batches from different females. These fish show no parental care, so after spawning they may eat their own eggs. To preserve the fry, move fertilized eggs to a separate tank with identical water conditions. The fry stay there until they reach a suitable size, usually about six months. Equip this nursery tank like the main tank, except use a simple sponge filter instead of the regular filtration system. This prevents the fry from being sucked in while providing adequate water quality. The incubation period is about 10 days, depending on temperature. Newly hatched fry need infusorians in the first few days. After a week, offer brine shrimp nauplii.

Health problems usually arise only from injury or unsuitable conditions that weaken immunity and trigger disease. If the fish show signs of illness, first check water parameters for excess levels or dangerous concentrations of toxic substances (nitrate, nitrite, ammonia). Once all parameters are normal, begin treatment.

Choose active fish with clean fins and no visible damage or sores. Check for the absence of white film, spots or signs of emaciation: this species is sensitive to stress during transport and when conditions change. In the shop, healthy fish swim in a school; individuals that stay apart, look sluggish or hide constantly may be sick or severely weakened. Buy a group of 8–10 to minimize stress and speed adaptation to your tank.