How many Corydoras should I have, and can different ones stay together?
Corys are shoaling fish and should be kept in groups of six or more individuals. Some people might think it is a good idea to have six different Corydoras species, but it's not; yes, they may seem happy enough sticking together, but that is only because you haven't given them a choice. If you keep them in good-sized groups of their own kind, you will see more natural behaviour.
What do Corydoras eat?
They're often thought of as being algae eaters and part of the cleanup crew and will be fine on any scraps that fall to the bottom, but this isn't the case. They get little to no nutrition from waste or algae. Corydoras need a balanced diet which should consist of frozen or live food such as bloodworm, brine shrimp, daphnia alongside good quality dried food such as wafers or catfish pellets.
What substrate should I have for Corydoras?
Corydoras are sand sifters; they take a mouthful, filter it through their gills, retain the food, and let the sand fall through. You can keep Corydoras on gravel but make sure it is fine or smooth with no sharp edges, but realistically sand would be best.
What tank size do Corydoras need?
There are several smaller Corydoras species; the most commonly seen are Corydoras Habrosus, Corydoras Pygmaeus, Corydoras Habrosus, and occasionally the Corydoras Hastatus. You could comfortably keep a group of six in a 60-litre aquarium. Pygmys and Hastatus usually spend a lot of time in the middle levels, so you should consider that when choosing tankmates. Most Corydoras don't exceed 8 cm in size; however, a 75-litre aquarium would be the best choice for the larger Corydoras species.