Cardinal Tetra

1 Species Overview

The cardinal tetra, also called the daylight tetra or new red lantern tetra, is a small-bodied fish. Its upper body has a bright blue-green stripe, and a red patch sits on the rear lower abdomen; the whole body carries a metallic sheen and sparkles, so some also call it the ‘red neon’ (honglvdeng).

Kingdom: Animalia

Phylum: Chordata

Class: Actinopterygii

Order: Characiformes

Family: Characidae

Genus: Paracheirodon

Species: Paracheirodon axelrodi

2 Appearance

The cardinal tetra is native to slow-flowing rivers in Brazil, Colombia, and Venezuela in South America. It is now kept by hobbyists as an ornamental fish for the aquarium.

Living fish are divided into cartilaginous and bony fish — sharks, ray-finned and lobe-finned fish, both of which first appeared in the early Devonian. The cardinal tetra has relatively high water requirements: it likes weakly acidic water and thrives at 24–26 °C. It prefers dim lighting and tends to stay in the lower water layers.

The cardinal tetra is 4–5 cm long, spindle-shaped and laterally compressed, slightly deeper-bodied than the neon tetra. It is omnivorous; feeding some animal foods during breeding helps keep its color vivid and bright. It has a gentle temperament, mixes easily with other tropical fish, is alert, and swims lively and cheerfully.

In a planted cardinal tetra tank you can mix other tropical fish and plant more aquatic plants, which provide shade and a more comfortable environment. Cardinal tetras are sexually dimorphic: males are slimmer and narrower, while females are broader with a swollen abdomen. Males also show brighter, more colorful bodies than females.

3 Care Basics

As a tropical fish, the cardinal tetra has high requirements for water quality and temperature, and it is a bottom-dwelling fish. A school of cardinal tetras swimming in an aquarium is a beautiful sight — here is how to keep them properly.

Cardinal tetra care demands close attention to water temperature and quality. The best growth temperature is 24–26 °C, and it prefers slightly acidic water. It stays in the lower water layers and does not need strong light, so plant plenty of aquatic plants for shade. Choose a low-intensity aquarium light bar and keep daily lighting short.

The cardinal tetra is omnivorous and will eat tubifex, mealworms, and prepared fish food. But feed a balanced mix; to keep the color vivid and bright, offer live foods periodically to promote healthy growth.

Also, you need not change water daily — a change every 3–5 days is enough. Keep the new water’s parameters consistent with the old, and add it slowly to avoid large swings in water conditions that would disturb the fish.

4 Tank Environment

The cardinal tetra is a small tropical fish, so creating a proper tropical-fish environment is essential. Because of its small size it is also timid, so it is best to plant some aquatic plants in the tank for it to hide among.

The cardinal tetra is strict about temperature — 24 °C is ideal, with a suitable range of 24–26 °C, and dim light. It is a bottom fish that stays in the lower layers; change water every 3–5 days, not too often, and never let the temperature swing high and low — use a heater. The tank should have broad-leaved plants to block strong light and create a dim, quiet environment. Cardinal tetras are timid, so avoid heavy foot traffic and loud noises near the tank. Feed small live foods to keep their color brilliantly shining.

5 Feeding

Although the cardinal tetra is small, do not overlook the importance of feeding — its color is directly tied to what it eats.

The cardinal tetra is omnivorous and eats tubifex, mealworms, and prepared fish food. Feed a balanced mix, and offer live foods periodically to keep the color vivid and bright and promote healthy growth.