PENGUIN TETRA | THAYERIA BOELKEI

The Penguin Tetra (Thayeria boelkei) is a peaceful, active, and attractive schooling fish native to the clear streams and tributaries of the Amazon Basin in South America. Its sleek, torpedo-shaped body is silvery with a distinct black stripe that runs from the middle of the body through the lower half of the tail, creating a “penguin-like” appearance—hence the name. This unique stripe and their upright swimming posture give them a charming, graceful look in the aquarium.

Adult Penguin Tetras typically reach about 2.5 inches (6 cm) in length and do best when kept in groups of at least six or more. Schooling helps them feel secure and reduces stress, allowing them to display their best coloration and natural behaviors.

Ideal water parameters:
Temperature: 74–82°F (23–28°C)
pH: 6.0–7.5
Hardness: 2–15 dGH

Tank setup: They prefer a well-planted aquarium with some open swimming space, subdued lighting, and a dark substrate that enhances their reflective colors. Driftwood and floating plants like Amazon Frogbit or Water Sprite help create a comfortable, natural environment. A 20-gallon tank or larger is ideal for a small school.

Diet: Penguin Tetras are omnivorous and easy to feed. Offer them a mix of high-quality flakes or micro pellets as a staple diet, supplemented with frozen or live foods like brine shrimp, bloodworms, and daphnia to promote color and vitality.

Temperament and tankmates: They are peaceful and make excellent community fish. Ideal companions include other small, calm species like tetras, rasboras, corydoras, livebearers, and dwarf gouramis. Avoid aggressive or fin-nipping fish.

Fun fact: Penguin Tetras have a unique swimming style—slightly angled upward—which gives them a distinctive “gliding” motion in the tank. Combined with their attractive markings and gentle temperament, they add a dynamic yet tranquil presence to any freshwater aquarium.