The Bottom Crew
One of the first bottom feeding fish many aquarists purchase is the albino Cory cat or one of its relatives. There are over 170 recognized species of Corydoras, with 100+ species yet to be given scientific names. They belong to the Family Callichthyidae and range throughout South America, from the Andes Mountains to the Atlantic coast, and from Trinidad to northern Argentina. Brochis and Aspidoras species occupy smaller, overlapping ranges and are included in this care guide as they have similar aquarium needs. All three genera are peaceful bottom feeders that can be kept in community aquariums. They are heavily armored and have sharp spines on their pectoral and dorsal fins. Care should be taken when handling them, as some species have a mild toxin in their spines.
Natural Habitat for Corydoras
Corydoras, Brochis and Aspidoras species inhabit smaller streams and rivers, backwaters, oxbows, ponds and marshy environments. The water is clear, slow moving and relatively shallow. The bottom is typically made up of sand or detritus, and the shoreline often has dense plant growth, offering them cover.
Water Requirements for Corydoras
Corydoras, Brochis and Aspidoras species are found in soft water with a low pH in the wild, however, many species sold today are commercially raised and tolerate a much wider range of water chemistry. A pH between 7.0 and 8.0, alkalinity between 3° and 10° dKH (54ppm to 180ppm) and temperature between 74° and 80° F are ideal conditions for most captive bred Cory cats and their relatives. Wild caught fish may require a pH of 5.5 to 7.0 and alkalinity below 3° dKH (54ppm). If the aquarium is kept in a room below 74°, use an Aqueon Aquarium Heater to maintain the correct temperature. Pristine water quality is essential to good health in these catfish. They should never be added to new aquariums or those that have been neglected. Maintain good filtration and change 10% of the water every week or 25% every 2 weeks using an Aqueon Aquarium Water Changer or Siphon Vacuum Gravel Cleaner. Don't forget to treat tap water with Aqueon Water Conditioner before refilling your aquarium!
Housing Recommendations for Corydoras
A 30-gallon aquarium is best for most species, although pygmy Corys such as C. hastatus, C. habrosus and C. pygmaeus can be kept in smaller aquariums. Because these fish like to congregate in groups, open areas should be available near the front of the tank. Some cover should also be provided for them to take refuge in. Substrate should be sand or fine gravel with rounded edges. Avoid jagged materials that could damage their barbels as they forage along the bottom.
Corydoras, Brochis and Aspidoras species are shoaling fish, meaning they like to hang out together. Different species can be mixed, and they will often group together. For best results, they should be purchased in groups of 5 or more. These catfish will sometimes dart to the surface to gulp air. This behavior is normal, however, gasping at the surface constantly may be an indication of water quality problems or low oxygen content. Unlike many catfish, which are nocturnal and can be secretive, Corys and their relatives tend to be out and about during the daytime. They can be kept with most peaceful community fish. Different species attain various sizes as adults, so species selection should be based on tank size and the types of fish you keep. Always consult an aquarium expert before buying any new fish for your aquarium.
What Do Corydoras Eat?
Corydoras catfish and their relatives are omnivores and typically feed on the bottom, although it is not uncommon for them to learn to come to the surface for food when hungry. Aqueon Bottom Feeder Tablets, Shrimp Pellets, Tropical Granules and Algae Rounds are all excellent foods for these catfish. For best results, feed a variety of high-quality foods and rotate your fishes' diet daily. Feed only what your fish can consume in 2 to 3 minutes, once or twice a day.
Corydoras Breeding Level – Difficult
Corydoras catfish and their relatives are egg depositors and are known to place their adhesive eggs among plants and even on the aquarium glass. Spawning often coincides with a drop in barometric pressure or temperature, and many breeders induce their fish to breed by doing partial water exchanges with slightly cooler water just before a rainstorm.