Wavy Corydoras

Adults of this catfish reach just over 4 cm in length. Its body appears stocky and robust, and its fins are short. In this species, the scales are transformed into rows of plates, which provide reliable protection against potential predators. Another protective feature is the first rays of the fins: they are thickened and pointed at the ends, forming a kind of spine. The fish's coloration is dark, complemented by light stripes and speckles that form a characteristic pattern.

The Wavy Corydoras inhabits South America, primarily in the basin of the lower Paraná River and coastal waters of southern Brazil and Argentina. It is a demersal fish, preferring to stay in the lower water layers among dense vegetation, where it finds shelter. In nature, the species is adapted to a tropical climate with water temperatures of 22–26 °C, a wide pH range from 6.0 to 8.0, and hardness of 2–25 dGH.

This catfish is known for its peaceful and friendly disposition. It prefers the company of its own kind rather than solitude. Corydoras undulatus coexists perfectly with other Corydoras species, as well as with non-aggressive fish of comparable size. Good tank mates for it include popular aquarium inhabitants such as Danios, Rasboras, and various small Tetras.

For a small group of 3–4 individuals, the optimal aquarium volume starts from 40 liters. When arranging decor, it is important to consider the need for a soft substrate and several shelters. These shelters can be natural materials, such as snags or dense plant thickets, or artificial decorative elements. Since the Wavy Corydoras originates from a subtropical climate, it is well adapted to relatively cool water—around 20–22°C. This allows it to be successfully kept even in aquariums without additional heating.

In its natural environment, this species feeds on small invertebrates, including worms, crustaceans, and insects, and also consumes organic plant matter. In aquarium conditions, Corydoras readily eat high-quality specialized dry foods in the form of sinking tablets or granules, as well as frozen foods such as bloodworms, daphnia, or brine shrimp. A varied diet is recommended to maintain the health and activity of the fish.

Breeding occurs in a spawning tank, where a pair or group of fish lays eggs on a substrate, such as plant leaves or glass. The spawning process is often stimulated by water changes. The female attaches the eggs to the chosen spot, after which fertilization is carried out by the male. The parents do not care for their offspring and may eat the eggs, so the adults should be removed after spawning is complete. Fry begin to feed independently after the yolk sac has been absorbed.

The species has a typical sensitivity for armored catfish to water quality, especially to the accumulation of organic waste in the substrate. If keeping conditions are violated, fin and skin lesions from bacterial infections are possible. The fish are extremely sensitive to certain chemical preparations and salts used in aquaristics, so treatment should be carried out with caution. Prevention involves maintaining a clean bottom and regular water changes.

When purchasing, choose active fish with clean skin, free of visible spots, sores, or fin damage. Healthy individuals should exhibit natural behavior for the species, actively exploring the substrate in search of food. Avoid purchasing fish from aquariums where dead individuals or specimens showing signs of emaciation have been observed, as this may indicate hidden infections or poor keeping conditions in the store.