Taxonomy & naming
Clarias dussumieri was described by the French zoologist Achille Valenciennes in 1840, part of the same Histoire naturelle des poissons project (with Georges Cuvier) that named a huge swath of the world's fish fauna. It belongs to the family Clariidae, the airbreathing or walking catfishes, and to the genus Clarias, which spans dozens of species across Africa and Asia. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) treats Clarias dussumieri as a valid species, distinct from the far more widely distributed Clarias batrachus with which it has sometimes been confused in older literature and in the aquarium trade.
The genus name Clarias is thought to derive from the Latin clarus, "clear" or "bright", though its exact original sense is debated; the species epithet dussumieri honors Jean-Jacques Dussumier, a French merchant-naturalist whose extensive collections from India and the Indian Ocean region supplied many of Cuvier and Valenciennes' type specimens. As a strictly Indian endemic, Clarias dussumieri is easy to mix up in trade literature with other regional Clarias, so the genus name alone is not a reliable guide to which species is actually being kept.
Morphology
Clarias dussumieri has the unmistakable walking-catfish body plan: an elongated, cylindrical trunk, a flattened, bony head, small eyes, and four pairs of long barbels around the mouth that it uses to feel out prey and cover in murky water. The dorsal and anal fins run in long, low bases almost the length of the body, converging near a rounded caudal fin, and the pectoral fins each carry a stout, serrated spine.
FishBase records a maximum length of about 10 in total length, with wild individuals recorded to over 3 kg — a reminder that length alone understates how much bulk this fish packs on as it matures. Like all catfish in this family, the skin is completely scaleless, which makes it more sensitive than scaled fish to copper-based medications and many general treatments; dose conservatively. A specialized suprabranchial (accessory air-breathing) organ lets it gulp atmospheric oxygen at the surface, an adaptation that lets it survive in poorly oxygenated or even temporarily dried habitats.
Habitat
This species is endemic to the Western Ghats of peninsular India, recorded from Goa, Karnataka, Kerala and Pondicherry along the southwestern coast. It favors the lower reaches of streams, rivers and canals with muddy or silty bottoms, and is also found in ponds, swamps and paddy fields — the kind of soft-bottomed, seasonally variable freshwater habitat typical of the Western Ghats lowlands.
Clarias as a genus tolerate an unusually wide temperature range (roughly 46–95 °F, with 82–86 °F considered optimal) and a moderate pH band of about 6.5–8.0, and their air-breathing physiology lets them persist in stagnant or low-oxygen water that would be lethal to most fish. This is a warm, soft-bottomed tropical Indian species, not a soft acidic blackwater specialist — it is built for muddy, mineral-moderate lowland water rather than for tannin-stained forest streams.
Feeding
Clarias dussumieri is predatory, taking small fishes and insects in the wild along with other invertebrates it can overpower in the mud and cover of its lowland habitat. As with other Clarias, it hunts mostly after dark, relying on its barbels as much as its eyes to locate prey in turbid water.
In captivity it is an opportunistic feeder that readily accepts large meaty foods — whole or chopped fish, prawn, and sinking pellets or pelleted catfish diets. Because it is a genuine piscivore that will swallow anything it can fit in its mouth, any tankmate must be too large to be eaten outright; this is not a fish to keep with small or slender-bodied species.
Mating
In the wild, spawning biology specific to Clarias dussumieri is not well documented, but breeding-and-conservation research on the species has established a reliable induced-spawning protocol, indicating that natural courtship and spawning triggers (seasonal rains, rising water) are not reliably reproduced in captivity. Sex can be distinguished by the genital papilla: males have a slender body and a conical, pointed papilla that becomes protruded and vascularized in breeding condition, while females have a blunter papilla that swells and oozes eggs when ripe.
As with most large Clarias, this species is not known to court and spawn spontaneously in home aquarium conditions; commercial and research breeding relies on hormone induction rather than natural pairing behavior.
Breeding
Clarias dussumieri is farm- and hormone-bred at commercial and research scale, not bred in the home aquarium. Published conservation-breeding work used the synthetic hormone Wova-FH (about 1.0 ml per kg body weight) to induce spawning, achieving roughly 97% fertilization and 99% hatch rates, with eggs hatching in about 25–30 hours at 79–81 °F; broodstock were successfully maintained in 150-litre glass aquariums fitted with biofiltration.
That protocol exists specifically because wild populations have crashed sharply enough — a 2011 Kerala survey recorded only 208 specimens — that researchers are recommending aquaculture-based conservation breeding to secure the species outside its shrinking natural range. This is not a fish that spawns for hobbyists; its reproduction is a matter of induced, managed hatchery technique aimed at conservation and aquaculture, not home fishkeeping.
In the aquarium
Clarias dussumieri is a genuine size-trap fish: it is often sold as an innocuous-looking juvenile but grows to about 10 in and can pack on well over 3 kg of body mass in nature, far beyond what the overwhelming majority of home aquariums can responsibly house. Anyone considering this species should plan for a very large, heavily filtered tank with a secure, weighted lid — Clarias are strong, determined air-breathers and will use any gap to escape, and this genus is a notorious invasive species outside its native range, so it must never be released into local waterways.
Because the skin is completely scaleless, treat it as medication-sensitive: use copper-based and other treatments at conservative, often half, dosing. The pectoral spines are stiff and can jab a keeper or snag a net, so move this fish in a container rather than netting it. It is nocturnal and predatory, so provide dense cover or a large hide, keep the substrate soft, and never house it with anything small enough to swallow — which, given its adult size, ends up being almost every other community fish.
Conservation
Clarias dussumieri is assessed by the IUCN Red List as Near Threatened, but the underlying data paint a more urgent picture: a 2011 survey across its native Kerala range recorded only 208 specimens, and researchers publishing in conservation-focused literature have recommended the assessment be revisited toward a higher threat category given the pace of the decline. As a Western Ghats endemic confined to a specific set of lowland streams, ponds and paddy-field habitats, it is exposed to habitat degradation, water pollution and pressure from agricultural land-use change across a comparatively narrow range.
The same research recommends aquaculture-based conservation breeding — the hormone-induced hatchery protocol described above — as a practical route to rebuilding stock and easing pressure on the wild population. Anyone acquiring this species in the trade should be aware it is a range-restricted endemic under real conservation concern, not a common farmed food fish, even though its genus includes species raised at enormous commercial scale elsewhere in Asia and Africa.