Penguin Tetra

Thayeria boehlkei

Also known as: Penguin, Blackline penguinfish, Hockey stick tetra

Water Parameters

• Temperature: 22–28°C
• pH: 6–7.5
• Hardness (GH): 36–268 ppm (2–15 dGH)

Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.

Care Summary

An instantly recognisable tetra, silver with a single bold black line that runs from the gill to the tail and kinks sharply downward into the lower tail lobe, and which hangs in the water at a curious nose-up, tail-down slant, hence the penguin and hockey-stick names. It is a hardy, active, adaptable schooling fish that reaches a good size for a tetra and needs a group of at least six and some swimming length to look its best; kept in too few, it can turn fin-nippy. Undemanding of water conditions and easy to feed, it suits a lively community of robust, similarly-sized fish, though slow or long-finned tankmates are best avoided. A distinctive, characterful, and genuinely easy schooler, provided the tank is covered against its jumping.

Tankmates

A hardy, active schooler for a lively community of robust, similarly-sized fish. Keep a group of six or more; in smaller numbers it can nip fins. Best with fast, short-finned tankmates rather than slow or long-finned ones such as bettas, guppies, and angelfish. A strong swimmer that needs some tank length, and an accomplished jumper, so keep the tank well covered.

Compatible with

• Black Skirt Tetra
• Red Eye Tetra
• Zebra Danio
• Bronze Corydoras
• Bristlenose Pleco
• Harlequin Rasbora
• Pearl Gourami

Avoid keeping with

• Betta
• Dwarf Gourami
• Guppy
• Angelfish
• Long Finned Species

Common Problems

• fin nipping in groups smaller than six
• jumping from open or poorly-covered tanks
• needing swimming length as an active fish
• ich

Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20