Corydoras

Corydoras is a large genus of freshwater armored catfish in the family Callichthyidae, comprising over 160 described species distributed across river systems east of the Andes, from Trinidad to northern Argentina. Their bony plate armor and barbels on both sides of the mouth are characteristic features. A remarkable adaptation allows them to perform intestinal breathing — surfacing to swallow air, which is absorbed through the intestinal wall — enabling survival in poorly oxygenated waters. Fine, rounded substrate such as smooth sand is essential; sharp gravel damages their sensitive barbels. Corydoras are highly peaceful and distinctly social, thriving in groups of five or more of the same species. Optimal water conditions are slightly acidic to neutral (pH 6.0–7.5) at 22–26°C. They feed on sinking tablets, frozen bloodworms, and bottom-dwelling detritus. Their breeding method — known as the T-position spawn, in which the female presses her mouth against the male's genital region — is one of the most studied and debated reproductive behaviors in freshwater fish. Eggs are deposited on glass or plant leaves.

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Sinking tablets, frozen bloodworms