Max Size: 4cm

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.


Costello tetra
Costello tetra
Costello Tetra
Quick Facts
Scientific NameHemigrammus hyanuary
Other NamesJanuary Tetra
OriginsBrazil, Peru
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 6+
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH6.0 - 7.0
GH2 - 15
74 - 80℉
23.3 - 26.7℃


In the home aquarium, the Costello Tetra will readily accept most good quality dried foods such as granules, flakes and sinking pellets. These modern food products have been developed to provide all adequate nutrition to maintain your fish's health and dietary requirements.

Providing additional foodstuffs such as live, frozen, and freeze-dried meals such as bloodworm, daphnia, and tubifex once or twice a week will provide additional benefits to your fish's health and well-being but is not a must for this fish.

It should be noted that bloodworms should only be given as an occasional treat and should not be used as the staple diet as they are difficult for fish to digest and can potentially cause blockages.

This fish is an omnivore in the wild, meaning it will consume some vegetable matter. Although most modern fish foods take this into account and include them in their products, you can still supplement your fish's diet with blanched vegetables such as spinach, broccoli, and zucchini. Ensure you do not overfeed your fish and remove any leftovers the following day.

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.

Other Tetras of interest

Adonis Tetra(Lepidarchus adonis)
African Moon Tetra(Bathyaethiops caudomaculatus)
African Red Eyed Tetra(Arnoldichthys spilopterus)
Arowana Tetra(Gnathocharax steindachneri)
Black Darter Tetra(Poecilocharax weitzmani)
Black Line Tetra(Hyphessobrycon scholzei)
View all Tetras
Date Added: 17/12/2020 - Updated: 22/11/2021 17:06:19