Penguin Tetra Care Guide - Aquarium Setup, Diet & Breeding

The Penguin Tetra is a slender, silvery characin distinguished by a dark horizontal stripe that extends from the middle of the body towards the tail. Its most recognisable feature is its unusual swimming posture: the fish often holds its body at a slight angle, with the head higher than the tail, giving it a characteristic forward-leaning appearance.

Despite its common name, it is not closely related to marine penguins or to the similarly marked Blackline Rasbora. The dark stripe and translucent fins create an understated but attractive appearance, while subtle golden or yellowish tones may show through on healthy, mature fish.

This is an active, peaceful schooling species that spends much of its time in the middle and upper levels of the aquarium. In a confident group, Penguin Tetras display lively social behaviour and regularly move together through open water, while still retaining a calm temperament towards other appropriately sized fish.

In nature, they are associated with shaded Amazonian waterways where overhanging vegetation, submerged branches and leaf litter break up the light. Their wild environment is structurally complex, and this background helps explain their preference for cover and their tendency to appear most comfortable when kept in a substantial group.

Penguin Tetras are native to the upper and central Amazon Basin in South America, with populations recorded in parts of Brazil, Peru and Bolivia. They inhabit slow-moving tributaries, forest streams and quiet waters associated with dense vegetation.

A group of Penguin Tetras should be given an aquarium of at least 75 litres, with a footprint of roughly 90 cm by 30 cm to provide useful swimming length. Use a fine, dark substrate or smooth gravel, combine open swimming space with dense planting around the sides and rear, and add driftwood, roots or leaf litter to create shaded retreats. Gentle to moderate filtration, subdued lighting and clear areas for schooling help replicate their quiet, vegetation-rich Amazonian habitat.

Up to 6 cm (2.4 in) in total length. Females are usually slightly larger and deeper-bodied than males.

Penguin Tetras are omnivores and thrive on a varied diet of quality small granules or flakes supplemented with foods such as baby brine shrimp, daphnia, mosquito larvae and other suitably sized frozen or live foods. Feed small portions that they can finish quickly, and vary the menu regularly to support colour, condition and breeding readiness.

Penguin Tetras are peaceful community fish and suit similarly sized, non-aggressive tankmates such as other medium-sized tetras, rasboras, peaceful barbs, pencilfish, Corydoras, small Loricariidae and gentle dwarf cichlids. They should not be kept with fin-nipping species, highly aggressive fish or large predators that could swallow them. Very small slow-moving fish may be unsettled by their active swimming, while long-finned species can occasionally be vulnerable if the group is cramped or understocked.

Penguin Tetras are egg-scattering free spawners that can be bred in a separate, dimly lit aquarium with soft, slightly acidic water and fine-leaved plants or spawning mops. A conditioned pair or small group typically scatters eggs among the vegetation, after which the adults should be removed because they may eat the eggs. Hatching usually occurs within around 24 to 36 hours, and the tiny fry initially require infusoria-sized food before progressing to larger live or powdered foods.

Females are generally fuller through the abdomen, particularly when carrying eggs, and may be marginally larger overall. Males tend to be slimmer and more streamlined, although the difference can be subtle outside breeding condition.