Penguin Tetra (Thayeria boehlkei)

The characteristic black marking of Thayeria boehlkei has given it its common names. You’ll sometimes see it called the Penguin Tetra (though, to be honest, it’s not quite white enough to ever be confused with an actual penguin.) and other times it’ll go as the Hockeystick Tetra (a silly name that accurately describes the bent shape of the black line running along the side of the fish and down the lower caudal fin lobe).

The species is native to the tributaries of the Upper Amazon in Peru and the Rio Araguaia of Brazil. Only three species exist in the genus, and these are all easily told apart. In T. obliquus, the black marking travels upwards from the caudal fin towards the dorsal fin, dissipating well before it gets anywhere close to the head, as it does in T. boehlkei. The rarely seen T. ifati has a somewhat similar stripe, but it appears far thinner and doesn’t travel as far along the caudal fin.

Aquarium care is simple enough. As always, keep this tetra in as large a group as possible. This will create the most natural behavior for this fish, reducing any skittishness or aggression among them. Fully grown specimen are between 2 and 3 inches in length, making this species ideal for smaller systems, particularly those that are heavily planted. With its unique appearance and tight schooling behavior, this has long been a favorite among planted aquarium enthusiasts, with none other than Takashi Amano using them to great effect.