Corydoras belong to the genus Corydoras in the armored catfish family Callichthyidae. Corydoras are a type of catfish, and many different species are today kept by aquarists. Corydoras, or Corys as they are affectionately called by their keepers, are peaceful and can be kept in tropical community aquariums. They are active and entertaining to watch, and can become very old in the aquarium if you provide them with favourable conditions. Do not be surprised if your Cory accompanies you for 15-20 years.
In the genus Corydoras we can today find over 180 described species. Many species kept by aquarists have not yet been scientifically described so this genus will most likely grow even larger in the future.
If you want to keep Corydoras, you should get at lest six individuals since Corydoras form large schools in the wild. In South America, you can find school consisting of thousands of Corydoras. Sometimes members of different species school together.
The native environment for Corydoras is slow-moving streams where the water is shallow, clear, soft and neutral or slightly acidic. Keep the pH-value in the aquarium slightly below 7 and strive for 5-10 degrees of hardness. Some Corydoras species do not cope well with salt, so you must research you particular species before you use salt as medication. Corys are quite hardy and adaptable, but they are sensitive to high levels of nitrate since this makes them susceptible to barbell infections.
Corys will search for food at the bottom of the aquarium, so sinking pellets are recommended. They will also eat sunken flake food, and occasional treats in the form of live or frozen meaty food is greatly appreciated. In the wild, Corydoras eat worms, insects, larvae, dead fish, plant material and other food stuffs that they manage to find while searching the bottom.
Corys do best in planted aquariums since this resembles their natural environment. Since Corys are bottom feeders you should not use a sharp substrate in the aquarium. Corys will search the substrate using their barbles and a sharp substrate can cause injury. In the wild, they are usually found over sandy or muddy bottoms. The substrate can also be covered in decomposing leaves. Corys like to burry themselves in the substrate.
If you notice that your Corydoras occasionally leaves the bottom to breathe air at the surface, there is no need to be alarmed. This is a normal behaviour in Corydoras and does not indicate gill infections. The fish draws air into its mouth and absorb it through the wall of its intestine. Left over air is then released through the vent. This fascinating form of breathing is an adaptation to low-oxygen waters.
One example of the many popular Corydoras species is the Bronze Corydoras (Corydoras aeneus). The females can reach a length of 3 inches (7 centimetres), while he males usually stay smaller. Since this species is really popular among aquarists, it is today commercially bred in many parts of the world. You can also find wild caught specimens in aquarium stores, but wild caught Bronze Corydoras tend to be more difficult to successfully spawn in aquariums.