Latin name

Paracheirodon axelrodi

Identification

The Cardinal tetra has an elongated body that is slightly flattened on the sides. The females are fuller than the males and have a concave edge to their anal fin.

Features of fish fins

This species of fish has five fins. The dorsal fin is small and high, consisting of seven to eleven rays. The pelvic fin is located slightly in front of the vertical line at the beginning of the dorsal fin and consists of five to six rays. The anal fin is quite long and notched and begins at the vertical line at the end of the dorsal fin. It consists of fifteen to eighteen rays. The caudal fin is strongly notched with rounded edges. The pectoral fin is located low and consists of seven to nine rays.

Fish colouring

The back of the cardinal tetra is olive-beige in colour. From the eyes to the adipose fin, there is a bright blue stripe that glows with a neon light. Below this is a wide, bright red stripe and the abdomen is whitish in colour. All fins are transparent, with only the dorsal and anal fins having a milky-white or bluish edging. The individual rays of the caudal fin may be red.

Distribution

It is widespread in the waterways of South America, particularly in the basins of the Orinoco and Rio Negro rivers.

Habitat

It inhabits shallow, standing waters that are overgrown with aquatic vegetation. It lives in water with a temperature of +23...+27 °C, a pH of 4.0–6.0, and a hardness of 5–12 °dH. It is a pelagic, non-migratory, gregarious fish. It prefers slow-moving water, channels and ponds.

Size

This species has a maximum body length of 3 cm (1.2″) for both males and females.

Behavior

Cardinal tetras are active during the day and live in shoals of thousands in their natural habitat. Depending on the water level during a particular season, they make small seasonal migrations up or downstream.

Food and feeding habits

Their diet consists of small worms and crustaceans.

Reproduction

For breeding, use an aquarium with dimensions of 30 × 25 × 25 cm. The female can lay up to 400 eggs. Depending on the water temperature, incubation lasts 22–30 hours and the larvae begin to swim after 3–4 days.

Aquarium conditions

In aquariums, quiet fish are kept in groups of five at a water temperature of +24... °C, with a pH of 5.5–6.2 and a hardness of 1–3 °dH. The aquarium should contain live plants. Stones and snags can be used as decorations.