Costello Tetra (Hemigrammus hyanuary)

The Costello Tetra is seen much less often in the hobby than it used to be and it is sometimes mistaken for the common Head and Tail Light Tetra, as it resembles an elongated variant of that species.

The Costello Tetra is a peaceful and somewhat placid fish and is best kept in a community tank with fish of similar size. It will not compete well with very boisterous or much larger tankmates as they are easily intimidated by more extensive or more rowdy species.

These Tetras are naturally a shoaling species and will fare much better when in the company of its kind. It would be best if you kept Costello Tetras in groups of at least six preferably more. Like most Tetras, it looks far more effective and natural-looking when maintained together, and the fish will also feel more secure.

The Costello Tetra has an elongated pale silvery-olive body with a distinct bright yellowish-green lateral stripe running along the gills to the caudal peduncle. On the caudal peduncle, you will find a large black spot. Their caudal fin is distinctly forked, and their fins are translucent with a delicate yellow hint.

Habitat

The Costello Tetras are endemic to the Central and Upper Amazon basin through Lake Hyanuary near Manaus in Brazil as well as Peru in South America. They inhabit soft and acidic brown coloured water stained from tannins in slow-moving rivers, streams and floodplain lakes covered with dense vegetation.

Other Tetras of interest

Diet & Feeding

The Costello Tetra is not fussy when it comes to the food they eat. It would be beneficial for them if you Provide a mix of good quality dried foods such as flakes, pellets and granules alongside small live and frozen foods such as daphnia, mosquito larvae and brine shrimp.

Sexual Dimorphism

It is relatively simple to differentiate male from female Costello Tetras. Males are slightly smaller and much slimmer than females and have a small hook on the anal fin that is absent in females. In contrast, females are larger and more rounded in the body and slightly less vibrant than males.

Breeding

Costello Tetras are relatively easy to breed, and in the confines of a well-planted tank, you may notice small numbers of young appear without any intervention from time to time.

However, if you wish to raise a higher quantity of fry, it would be better to set up a small separate breeding aquarium. This tank should contain soft, acidic water, with the temperature being towards the high end of the recommended range. You should also add clumps of Java moss or a few bunches of fine-leaved plants to the breeding tank to give the fish a place to scatter their eggs, and you should provide very gentle filtration using a small air-driven sponge filter. It would be best if you did not dedicate lighting in the tank, as eggs and fry tend to be light sensitive.

Before you attempt to spawn these Tetras, you should condition them on small meaty live or frozen foods. You can then acclimate a mix of both males and females into the breeding tank in the evening. The next morning, when sunlight hits the tank, spawning should begin.

You should remove the parents immediately after spawning stops as they will consume the eggs. Many hobbyists use fine mesh on the bottom of the tank; this is so the eggs can fall through safely, away from the attention of the adult fish.

The eggs will usually hatch within 24-36 hours, and the fry should become free swimming 72-96 hours after that. It would be ideal if you kept the tank in darkness once eggs have been scattered as this will protect them and the developing sensitive young fry from being damaged by bright light.

The babies will initially feed on their yolk sacs once they have consumed it you should then feed them infusoria followed by microworm and baby brine shrimp as they develop.

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