Olga cory (Corydoras simulatus) care guide

Group

Freshwater fish

Other names

Olga corydoras, Corydoras simulatus

Family

Callichthyidae (armoured catfishes)

Origin

Colombia: the upper Meta River system (Orinoco drainage); type locality the Río Ocoa near Puerto López.

Water

freshwater

Maximum size

4.9 cm

Temperature

20–25°C

pH

6.2–6.4

Hardness

Soft, slightly acidic water preferred

Minimum tank

80 litres

Care level

intermediate

Temperament

peaceful

Care

A long-snouted Corydoras for a group of six or more. Around 80 litres suits a group (our estimate from adult size). Use soft sand, or at least smooth rounded gravel: sharp or chipped gravel wears down the barbels, which then become infected. Add driftwood, plants and some shade from overhanging wood, rockwork, tall or floating plants, while leaving open sand for foraging. Keep current gentle and the water well oxygenated, and do regular partial water changes, as Corydoras are sensitive to nitrate and dirty substrate. FishBase notes it comes from clean, clear water with some current, so good filtration and oxygenation matter. PlanetCatfish gives 20–25 °C and a narrow pH of 6.2–6.4, which reflects the wild habitat; FishBase gives pH 6.0–8.0. Aim for soft, slightly acidic, very clean water and avoid sudden changes. Identification and sexing: a long-nosed cory that closely resembles several other species (hence the name simulatus, "imitating"); check photos and the supplier's origin. Females grow larger and are noticeably broader and fuller-bodied when seen from above; mature males are slimmer and have more pointed tips to the paired fins. Name: still placed in Corydoras by PlanetCatfish and FishBase. Status: IUCN Vulnerable (assessed 2020). FishBase notes low population resilience, so captive-bred stock is preferable and wild fish should be kept carefully. Sources: PlanetCatfish (planetcatfish.com/common/species.php?speciesid=392); FishBase (fishbase.se/summary/Corydoras-simulatus.html). Checked October 2026.

Diet

An omnivorous scavenger that sifts the sand for small invertebrates. Offer good-quality sinking pellets, tablets or granules as the staple, plus frozen or live bloodworm, Daphnia, brine shrimp and small worms several times a week (bloodworm, white worm and other small worms are good conditioning foods). Make sure food actually reaches the bottom, as faster mid-water fish will take it first, and feed some after lights-out.

Breeding

PlanetCatfish has no aquarium breeding report. Anyone trying should follow the usual long-nosed Corydoras approach: condition a group with plenty of live and frozen foods, keep the water soft and clean, and trigger spawning with a large, slightly cooler water change. Eggs are usually stuck to the glass or plants; move them to a separate container and raise the fry on microworm and baby brine shrimp. Given its Vulnerable status, a successful breeding is worth reporting to PlanetCatfish.

Compatibility and tank mates

A peaceful shoaling catfish for a calm community of similar-sized fish: small tetras, pencilfish, hatchetfish, rasboras, dwarf cichlids such as Apistogramma, and other Corydoras or small plecos. It suits a calm tank with clean, well-filtered water. Avoid large or boisterous cichlids, fin-nippers that pester bottom-dwellers, and any fish big enough to swallow it. Very small shrimp fry may be eaten, but adult shrimp and snails are left alone.

Last updated 5 October 2026. Community-edited care guide on Aquatic-Auctions.