Australian Blue-eye

Adult size ranges from 3 to 7 cm. Fish vary considerably in size depending on their geographic origin: northern Australian blue-eyes are larger with more elongated fins than those from southern regions. The body has a yellowish tone with a silvery sheen on the head. The species is named for its distinctive blue iris.

This fish comes from the east coast of Australia and nearby island territories. The species inhabits diverse natural biotopes: swamps, clear freshwater lakes and streams, and brackish waters, mangrove swamps and salt marshes.

Most of these fish are peaceful and calm, getting along well in a community tank with tank mates of similar size and temperament, such as tetras, barbs, catfish and others. Schooling is recommended, with a group of at least 8–10 individuals. The males of northern varieties can be quite aggressive toward each other, especially during spawning, staging fierce fights. Weaker individuals sometimes die from their injuries.

A small school of southern blue-eyes needs a minimum of 60 litres; northern forms require more space due to their larger size. The tank can feature dense plant areas alternating with open swimming space. A few natural or artificial roots add to the aesthetics. If the australian blue-eye was raised in an aquarium or on a farm rather than wild-caught, it will cause no problems. It is enough to recreate water conditions similar to those where it was previously kept. Thanks to its high adaptability, conditions can be gradually changed during tank maintenance to suit your needs and optimize care costs. It can be kept in brackish water at a salt concentration of up to 10–15 g per litre.

Since this fish feeds at the surface and in the water column, sinking foods are not desirable. When possible, enriching the diet with live foods such as fine bloodworms, brine shrimp and daphnia is recommended.

In nature, the breeding season runs from October to December, but in a home aquarium with stable parameters it can begin at any time. Fish use sticky threads to attach eggs to the surface of fine-leaved plants or moss; artificial plants also work. Spawning lasts several days, during which the female lays several batches of eggs that may be fertilized by several males. The incubation period is 10 to 21 days, depending on temperature. These fish lack parental instinct, and adults often eat both their own eggs and fry. In a densely planted tank, a small percentage of offspring may survive. To preserve all the fry, eggs can be carefully moved to a separate tank with identical water conditions, where the young can then be reared. Feed specialized powdered foods and/or brine shrimp nauplii.

Health problems arise only with injury or unsuitable conditions that weaken the immune system and lead to disease. At the first signs of illness, check water parameters for values exceeding safe ranges or the presence of toxic substances such as nitrites, nitrates or ammonia. If abnormalities are found, normalize all parameters, then begin treatment.

When buying, choose active, vigorous fish with clean fins and no visible damage or coating on the body. Avoid fish showing sluggishness, rapid breathing or clamped fins, as these may indicate stress or hidden disease. Since the species has wide geographic variation, ask the seller about the origin of the stock, as northern and southern populations differ in size and colour intensity. Before purchase, ensure the fish are kept in conditions close to those recommended for the species and show no signs of starvation. Since Pseudomugil signifer is a schooling species, buy a group of 8–10 individuals at once to minimize stress during acclimation to the new tank. If possible, observe the fish in the shop: healthy ones should be curious and show natural social activity.