Thayeria boehlkei is a species of characin fish endemic to the Amazon river basin and Araguaia river, in Peru and Brazil respectively. The species is popular with aquarium hobbyists where it is traded under a variety of common names including blackline penguinfish, blackline Thayeria, hockey-stick tetra, penguin fish and penguin tetra.
Thayeria inhabits small streams and the margins of smaller rivers in the Amazon Basin of lowland Amazonia, where its is part of the highly diverseNeotropical fish fauna.
The species was previously misidentified as Thayeria sanctaemariae and Thayeria obliqua. T. obliqua is a superficially similar, but different species of Thayeria