Sixray Corydoras

About

Sold as a 'false corydoras', this tiny catfish has spent fifty years being reassigned. Aspidoras is a genuine genus — Corydoras World places it in lineage 2, closely related to Scleromystax, and describes it as a small group of very active fish rarely reaching more than 55 mm SL, with 19 described species — and Seriously Fish gives the single feature that separates the two on a dissecting table: Aspidoras has two cranial fontanels where Corydoras has one. But this particular fish may not be an Aspidoras at all. It was described in 1970 as Corydoras pauciradiatus, moved into Aspidoras, returned to Corydoras by Tencatt et al. in 2022, and placed in the resurrected Gastrodermus by Dias et al. in 2024 — the same lineage-5 genus that now holds the pygmy cory. FishBase and the Catalog of Fishes both list Aspidoras pauciradiatus as a superseded combination, and Corydoras World's Aspidoras index of 18 species no longer contains it. The ending is not settled: FishBase and the Catalog of Fishes write the masculine Gastrodermus pauciradiatus, Corydoras World writes the neuter Gastrodermus pauciradiatum, and we file under the two-source spelling while keeping every combination searchable rather than pretending the question is closed. In the tank it behaves like the small cory it looks like — a peaceful shoaler that sifts fine sand — with one warning worth repeating: Seriously Fish says it 'requires stable, clean water conditions and should never be added to a biologically immature set-up'. The 'sixray' name is literal: six soft dorsal-fin rays, where other Aspidoras have seven.

Care

A group of 6 or more over fine sand in a densely planted tank of at least 60 × 30 cm, with clean, well-oxygenated, slightly acid water. Never add it to a newly cycled tank — Seriously Fish singles this species out as intolerant of an immature set-up. Its barbels are easily damaged, so sand rather than gravel is a welfare requirement, and tankmates should be small characins, dwarf cichlids and other peaceful nano fish.

Diet

Omnivore leaning strongly to small live and frozen animal food — bloodworm, daphnia, cyclops, tubifex — with sinking micro-pellets and crushed wafers as the dry base. Food must reach the substrate.

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.

Sold in Lithuania

These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.

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Frequently asked questions

What tank size does a Sixray Corydoras need?

A Sixray Corydoras needs an aquarium of at least 54 litres (14.3 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Sixray Corydoras need?

Sixray Corydoras does best at 20–27 °C (68–80.6 °F), pH 6–7.2 and a general hardness of 2–12 °dGH.

What group size does a Sixray Corydoras need?

Sixray Corydoras is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.

Is the Sixray Corydoras suitable for beginners?

Sixray Corydoras 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.

Sources

• FishBase — Gastrodermus pauciradiatus (Weitzman & Nijssen, 1970)
• Seriously Fish — Aspidoras pauciradiatus (Corydoras pauciradiatus)
• AquaInfo — Aspidoras pauciradiatus – Sixray corydoras
• Corydoras World — Gastrodermus pauciradiatum (species page)
• Corydoras World — Gastrodermus (lineage 5 genus index)
• Corydoras World — Aspidoras (lineage 2 genus index)
• Eschmeyer's Catalog of Fishes — pauciradiatus, Corydoras (spid 4795)