Dwarf corydoras (Corydoras hastatus) care guide

Group

Freshwater fish

Other names

Dwarf cory, Dwarf corydoras, Dwarf catfish, Tail spot pygmy catfish, Micro catfish

Family

Callichthyidae (armoured catfishes)

Origin

Amazon and Paraguay basins in Brazil, Bolivia, Paraguay and north-east Argentina – shallow backwaters, swamps, floodplain lakes and small side channels.

Water

freshwater

Maximum size

3.2 cm

Temperature

20–26°C

pH

6–7.5

Hardness

Soft to medium, 2–12 dGH

Minimum tank

54 litres

Care level

intermediate

Temperament

peaceful

Care

A tiny cory that behaves more like a little tetra: it spends much of its time swimming in midwater in a loose shoal rather than grubbing on the bottom. Its large eyes, forward-facing mouth and well-forked tail all reflect this. Keep a group of at least six, and ideally ten or more – in a big group it is far more confident and interesting to watch. Seriously Fish suggests a tank with a base of 60 × 30 cm (around 54 litres). Plant it well, leave open swimming space in the middle, and use a soft sand substrate so that when it does forage on the bottom its barbels are protected. Filtration should be gentle, and a sponge filter is safest for such small fish. Keep it at about 20–26 °C, pH 6–7.5, in soft to moderately hard water, and keep that water clean: regular partial changes, no build-up of nitrate and a tidy substrate. Like other corys it is sensitive to salt and to many medications. Wikipedia quotes warmer aquarium temperatures (24–29 °C), but the Seriously Fish range is used here. It is easily told from the pygmy cory (Corydoras pygmaeus) by the dark, roughly diamond-shaped spot on the tail base and the lack of a dark stripe along the body. In the wild it often swims with small tetras that share a similar tail spot. The valid name since the 2024 revision is Gastrodermus hastatus (an older synonym is Corydoras australe), but it is still sold as "Corydoras hastatus". It turns up less often in shops than the pygmy and salt-and-pepper corys. FishBase lists it as Least Concern on the IUCN Red List. FishBase gives a smaller maximum size (2.4 cm) than Seriously Fish (3.2 cm). Sources: Seriously Fish (seriouslyfish.com/species/corydoras-hastatus/); FishBase (fishbase.se/summary/Corydoras-hastatus.html); Wikipedia (en.wikipedia.org/wiki/Corydorashastatus). Checked October 2026.

Diet

An omnivore that, unusually for a cory, feeds partly on tiny drifting animals in open water. Offer plenty of small live foods such as Daphnia and brine shrimp nauplii, along with good small dried foods and freeze-dried bloodworm. Do not expect it to survive on leftovers.

Breeding

Use two or more males to each female; females grow larger and become broader and deeper-bodied when ripe. Condition the group on small live foods, then trigger spawning with a 50–70% change of soft, cooler water and extra aeration, repeating daily until they spawn. Eggs are stuck to the glass or plants; Wikipedia notes females may lay 30–60 eggs spread over several days. Remove the adults or the eggs, and many breeders add a little methylene blue or an alder cone or two to keep fungus at bay. Eggs usually hatch in 3–4 days, and the fry take microworm and newly hatched brine shrimp once the yolk is used up. The fry are not the easiest to raise but do better over a thin layer of sand.

Compatibility and tank mates

Peaceful, but its tiny size means tankmates must be chosen with care. Keep it with other very small, gentle fish such as small tetras, rasboras, pencilfish and other nano species, or with shrimps and snails. Avoid anything large enough to swallow it, and boisterous fish that would outcompete it for food.

Last updated 4 October 2026. Community-edited care guide on Aquatic-Auctions.