Horseman's Cory
Osteogaster eques
Callichthyidae
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About
First, the trap: this is not the serpae tetra. Hyphessobrycon eques is a red characin and Osteogaster eques is an armoured catfish; the epithet is shared because both were named for the same Latin word — AquaInfo glosses eques as 'Knight, Horseman or Rider' — and nothing else about the two fish matches. This one is a mid-sized cory with flanks that shift from dark to turquoise depending on the substrate it sits on, an orange bar behind the gill cover and orange along the back and caudal edges. It is noticeably busier than most cories: AquaInfo describes fish that 'swim back and forth endlessly' when the group is large enough, and both Seriously Fish and AquaInfo ask for a 90 cm base rather than the 60 cm that suits a sterbai or a panda — that footprint, not the 6 cm body, is the real gate on this species. Buy it carefully, because it is rarely stocked and AquaInfo warns that what shops offer under the name is more often a nicely coloured bronze cory; Seriously Fish adds that it is also confused with the Venezuelan cory. Its name has come full circle. Described in Corydoras by Steindachner, it was moved to Osteogaster by Cope in 1894 and folded back into Corydoras by Gosline in 1940; the 2024 Corydoradinae revision resurrected Osteogaster and put it back, so FishBase, Corydoras World and the Catalog of Fishes now write Osteogaster eques while shop labels and older literature still say Corydoras eques. The epithet is a noun in apposition — a horseman — so unlike aeneus becoming aenea in the same feminine genus, eques does not change its ending.
Care
A group of 6 or more (AquaInfo says preferably many more) over fine sand, in a tank at least 90 cm long — both Seriously Fish and AquaInfo set that footprint, which is longer than most cories need. Keep the water clean, cool-ish and well oxygenated, feed sinking food that actually reaches the bottom, and never rely on gravel: AquaInfo notes that sharp grains damage the barbels and the resulting infection can cost them entirely.
Diet
Omnivorous substrate forager with a small mouth; sinking granules, tablets and wafers plus frozen or live bloodworm, daphnia and tubifex. It does not feed on detritus, so food must be delivered to the bottom.
Tankmate compatibility
Gets along with (250)
Possible with care (106)
Avoid (62)
Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.
Telling males from females
What works for this species, most reliable first.
- Width from aboveStrong · from about 8 months, once they are adult-sized
Corydoras are sexed from directly above, never from the side. Look down at the group while they rest on the sand.
- Bristles and cheek spinesA hint only · from about a year
Male plecos grow odontodes — spiny growths on the cheeks and along the leading pectoral rays. Bristlenose males additionally grow branching tentacles across the snout and over the top of the head.
Also in these lists
Similar species
Same category and the closest water parameters — if this species isn't quite it, start here.
Health
Disease guide entries relevant to this species — worth a read before you reach for medicine.
The full disease guide →Sold in Lithuania
These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.
These links are unpaid: we get nothing for them and ask for nothing.
Frequently asked questions
- What tank size does a Horseman's Cory need?
- A Horseman's Cory needs an aquarium of at least 81 litres (21.4 US gallons) with a footprint at least 90 cm (35.4 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Horseman's Cory need?
- Horseman's Cory does best at 20–26 °C (68–78.8 °F), pH 6–8 and a general hardness of 2–15 °dGH.
- What group size does a Horseman's Cory need?
- Horseman's Cory is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.
- Is the Horseman's Cory suitable for beginners?
- Horseman's Cory sits in the middle of the difficulty scale — manageable for a careful beginner who has done the reading, but it has specific needs worth researching first.