The South American Corydoras genus is a freshwater temperate and tropical fish and is also the sole genus in the armored catfish subfamily Coradinae. The name Corydoras is derived from the Greek kory(helmet) and doras (skin) – referring to the fish’s armor. Aquarists commonly refer to them as corys, or cory catfish. Corydoras is by far the largest genus of neo-tropical fishes, with more than 142 species. In addition, many variants exist; in fact, several hundred Corydoras species are not yet classified, but are nevertheless kept by aquarists.
Corys are small fish, ranging from 25 to 120 millimetres. They are native to the slow-moving and almost still (but seldom stagnant) streams and small rivers of South America, or in smaller-sized streams, along the margins of larger rivers and in marshes and ponds, where the water is shallow and very clear. The banks and sides of their habitat are covered with a dense growth of plants, and these are the areas where the corys are generally found. Most species of this family are bottom-dwellers, and they forage in sand, gravel, or detritus.
They inhabit a wide variety of water types but tend to prefer soft, neutral to slightly acidic or slightly alkaline water. They can tolerate only a small amount of salt (some species tolerate none at all) and do not inhabit environments with tidal influences.
Corydoras Diet
In the wild, their main food is bottom-dwelling insects and insect larvae and various worms, as well as some vegetable matter. Although corys are not piscovores (fish-eaters), they will eat flesh from dead fishes. Their feeding method is to search the bottom with their sensory barbels and suck up food items with their mouth, often burying their snout up to their eyes. This is one of the reasons a soft sand substrate is preferable for corys.
A unique form of insemination has been described in Corydoras aeneus. When these fish reproduce, the male will present his abdomen to the female. The female will attach her mouth to the male’s genital opening, creating the well-known “T-position” so many Corydoras exhibit during courtship. The female will then drink the sperm. The sperm rapidly moves through her intestines and is discharged together with her eggs into a pouch formed by her pelvic fins. The female can then swim away and deposit the pouch contents somewhere she considers safe. Because the T-position is exhibited in other species than just C. aeneus, it is likely that this behavior is common in the genus.
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