Care
The Pygmy Cory is a peaceful little species, ideally suited to smaller softwater aquaria. Due to its diminutive adult size, it is not suitable for the general community aquarium as it may be intimidated by or preyed upon by larger tankmates. Mature, densely planted nano tanks would be perfect for this pretty, shoaling catfish. There should be a sandy substrate in order to protect the delicate sensory barbels, and some shady hiding spots amongst driftwood and broad leaved plants. Floating plants can also be useful in helping to diffuse bright lighting. Peat filtration will help to keep the water soft and acidic, and the tannins released will result in the fish showing their best colours. Unusually for a Corydoras catfish, this delightful species spends a good deal of time hovering in midwater. Pygmy Cories should always be maintained in large sized groups of at least 10 specimens; this will not only give them more confidence, but will result in a more effective, natural-looking shoal. Other tankmates could include tiny sized characins such as Ember Tetras, micro Rasboras (Boraras spp.), or small ornamental shrimps such as Red Crystals or Cherries. Frequent partial water changes are a must, as these fish can be very sensitive to elevated nitrate levels. Corydoras have the ability to breathe air intestinally, so a small gap should be left between the surface of the water and the cover slides in order for the fish to come up to the surface and take air in. It may do this numerous times per day. This species may sometimes be confused with G. hastatus, but the two can be told apart fairly easily as G. pygmaeus has a dark stripe that runs along the entire length of the lateral line from the tip of the snout and onto the caudal fin (this is lacking in G. hastatus).
Gastrodermus was recently split from Corydoras and contains all the elegans group, together with the pygmy corys.
Feeding
Offer a variety of appropriately sized foods, such as small sinking catfish pellets, micro granules, crushed flake, mini-bloodworm, white mosquito larvae, daphnia, vitamin-enriched brineshrimp, and baby brineshrimp.
Breeding
This species is said to be a little more difficult to breed than other members of the genus, as it can be difficult to raise the miniscule fry. It may be easier to attempt reproduction of this species in a dedicated breeding tank, set up with parameters matching the main tank but instead filtered by a small air driven sponge filter which should prevent any fry from being drawn in. A cooler water change may trigger your fish into spawning in the classic Corydoras "T-position". Soft, acidic water seems to be essential (peat filtration suggested) and a ratio of 2 males to every female tends to work best. The 1mm eggs (numbering up to 100 per female) are individually deposited, usually on the glass or amongst fine-leaved plants. Once spawning is over, the adults should be acclimatised back to the main aquarium, and the eggs can then be raised in the safety of the breeding tank, away from any predators. Many aquarists find that the addition of a small amount of methylene blue or an alder cone helps to prevent the eggs from fungussing, but any that do still fungus should be immediately removed to prevent it spreading to healthy eggs. A sand substrate actually seems to work better than a bare bottomed tank in preventing disease in this species. All being well, the eggs should hatch within 3 to 5 days, depending on water temperature. The fry will initially feed from their yolk sacs and can then be offered microscopic foodstuffs such as infusoria for the first few days, moving on to baby brineshrimp (Artemia nauplii) and microworms as they grow.
