Corydoras agassizii

Corydoras agassizii is a small, freshwater species of armored catfish belonging to the diverse family Callichthyidae. It is a popular fish within the aquarium trade, prized for its peaceful nature and distinctive patterning. The species is native to several major river systems in South America, where it inhabits slow-moving, shallow waters. Its scientific name honors the renowned Swiss-American naturalist and geologist Louis Agassiz.

Description

This catfish typically reaches a standard length of around 5 to 6 centimeters. Its body is protected by two rows of overlapping bony plates, a characteristic feature of the subfamily Corydoradinae. The base coloration is a pale, silvery-beige, overlaid with a striking pattern that includes a prominent dark stripe running horizontally from the snout through the eye to the base of the caudal fin. The dorsal fin often displays a dark blotch, and the body may be speckled with irregular dark markings. The adipose fin is usually transparent, and the barbels around the mouth are used for sifting through substrate in search of food.

Distribution and habitat

The species is found in the upper reaches of the Amazon River basin, with its range extending into the Solimões River and the Juruá River systems. It is also recorded in the Madeira River drainage and the Purus River basin. Its distribution spans parts of Brazil, Peru, and likely Bolivia. Corydoras agassizii inhabits shallow, slow-moving tributaries, small streams, and flooded forest areas. These environments typically feature soft, sandy or muddy bottoms littered with leaf litter, branches, and other detritus. Water conditions in these blackwater and clearwater habitats are generally soft and slightly acidic.

Behavior and ecology

Like other members of its genus, it is a benthic, social fish that forms loose shoals, often mingling with other small Characiformes and Siluriformes. It is a facultative air breather, capable of gulping atmospheric air at the water's surface, an adaptation facilitated by its highly vascularized intestine. This behavior is thought to be an advantage in the warm, oxygen-poor waters of its native habitat. Its diet consists primarily of small invertebrates, worms, and organic detritus, which it locates by probing the substrate with its sensitive barbels. Spawning involves the classic "T-position" seen in many Corydoras species, where the male fertilizes eggs held between the female's pelvic fins.

In the aquarium

A long-established favorite among aquarists, it is valued for its hardiness, peaceful demeanor, and useful scavenging habits. It thrives in a well-maintained aquarium that mimics its natural habitat, with a soft, sandy substrate to protect its delicate barbels, plenty of hiding places among driftwood and plants, and subdued lighting. Ideal tankmates include other small, peaceful community fish such as many tetra species, small rasbora, and dwarf cichlids from South America. A diet of high-quality sinking pellets, along with occasional offerings of live or frozen foods like bloodworms or brine shrimp, is recommended. Successful breeding in captivity is achievable, often triggered by cooler, partial water changes to simulate seasonal rains.

Taxonomy and naming

The species was first described scientifically in 1876 by the Austrian ichthyologist Franz Steindachner based on specimens collected from the Juruá River. The specific epithet, agassizii, was chosen to honor Louis Agassiz, a pioneering figure in the study of natural history, ichthyology, and glaciology. Agassiz founded the Museum of Comparative Zoology at Harvard University. Within the genus Corydoras, it is part of a complex of similarly patterned species, and precise identification can sometimes be challenging due to variations across its range and similarities to relatives like Corydoras ambiacus.

Category:Freshwater fish of South America Category:Fish of the Amazon basin Category:Fish described in 1876