Catfish · waters

The waters behind the fish

The catfish come from wildly different waters — a tea-black Amazon tributary hung with driftwood, a rapids in the Congo, a Rift lake where a cuckoo catfish robs a cichlid’s mouth, a monsoon-swollen Mekong, a cool European river holding a two-metre wels. Knowing which system a species comes from — its temperature, flow, hardness and how big its river is — is the foundation of keeping it well, and explains why an Amazon bumblebee catfish and a European wels want such different tanks. Here are the freshwater systems that shaped 555 of the 579 species in this atlas.

The Amazon & Orinoco

203 species

Tropical South America · the Amazon, Orinoco & the Guianas

The greatest catfish water on Earth. The Amazon and Orinoco basins and the Guiana Shield rivers hold the long-whiskered pimelodids (the pictus, the redtail Phractocephalus, the shovelnoses Sorubim and Pseudoplatystoma), the thorny/talking doradids (raphael, Megalodoras, Oxydoras), the driftwood auchenipterids, the banjo aspredinids and the bubble-nesting callichthyines (Hoplosternum, Megalechis, Dianema). Warm, soft, often blackwater — and home to both the smallest hoppers and the metre-long river monsters, so the size trap is sharpest here.

The Paraná–Paraguay & eastern Brazil

31 species

Subtropical South America · the La Plata basin & the Brazilian coast

The Paraná, Paraguay and Uruguay rivers of the La Plata basin, the vast Pantanal wetland and the coastal rivers of eastern and southern Brazil. A realm of Rhamdia and Pimelodella (Heptapteridae), the bumblebee Microglanis and other Pseudopimelodidae, southern doradids and callichthyines, and the giant Paraná pimelodids. Ranges from tropical floodplain to cool, temperate southern river — several of these catfish are not warm-water fish.

The Congo basin

50 species

Central Africa · the Congo (Zaire) river & its tributaries

The immense rainforest river of Central Africa — the world's second-largest by discharge. The Congo and its tributaries (the Kasai, Ubangi, Lualaba) hold a wealth of squeakers (Synodontis), the electric catfish Malapterurus, the bagrid-like Chrysichthys and Auchenoglanis, air-breathing Clariidae (Clarias, Clariallabes, Channallabes), the schilbeid 'glass' cats and the little African loach catfishes (Amphiliidae) of the rapids. Warm, often soft and tannin-stained water.

West Africa & the Niger

28 species

West Africa · the Niger, Volta, Senegal & the Guinean rivers

The Niger and Benue, the Volta, the Senegal and Gambia, and the short forest rivers of Upper and Lower Guinea. The African aquarium catfish heartland: featherfin and other squeakers (Synodontis), the walking catfish Clarias and Heterobranchus, the electric catfish Malapterurus, the schilbeid butter/glass cats (Schilbe, Parailia), the bagrid-like Chrysichthys and Bagrus, and the loach catfishes of the rapids. Warm, seasonally flooded, mostly soft water.

The Nile & the Rift lakes

27 species

Eastern & Northeastern Africa · the Nile, the Great Lakes & the Zambezi

The Nile from the Sudd to the delta, the great Rift Valley lakes (Tanganyika, Malawi, Victoria, Turkana) and the Zambezi. Home to the celebrated cuckoo catfish (Synodontis multipunctatus), which slips its eggs into the mouths of brooding cichlids in Lake Tanganyika, and to many other Synodontis, the huge Nile Bagrus, the vundu Heterobranchus, air-breathing Clarias and the electric catfish. From clear rift-lake shallows to muddy floodplain.

The Indian subcontinent

31 species

South Asia · the Ganges, Brahmaputra, Indus & the peninsular rivers

The Ganges and Brahmaputra, the Indus, the peninsular rivers (Godavari, Krishna, Kaveri) and the hill streams of the Western Ghats and Sri Lanka. A rich catfish fauna: the bagrids Mystus, Sperata and Rita, the sheatfish Wallago and Ompok, the goonch Bagarius, the venomous stinging catfish Heteropneustes, the walking catfish Clarias, the schilbeid Ailia, and the hillstream Glyptothorax. Monsoon-driven water, from warm plains rivers to cool, fast uplands.

The Mekong & mainland SE Asia

82 species

Indochina · the Mekong, Chao Phraya, Irrawaddy & Salween

The floodplain rivers of mainland Southeast Asia. The Mekong is the home of the shark catfishes — the iridescent 'shark' Pangasianodon hypophthalmus and the critically endangered Mekong giant catfish — alongside the bagrids Hemibagrus and Mystus, the sheatfish Wallago, the goonch Bagarius, the glass catfish Kryptopterus, the walking Clarias and the leaf-mimic frogmouth Chaca. The definitive size-trap water: several of these are farmed by the tonne and reach two metres or more.

Sundaland & the Malay archipelago

46 species

Sundaland · the Malay Peninsula, Sumatra, Borneo & Java

The forest streams, blackwater peat swamps and great rivers of the Malay Peninsula, Sumatra, Borneo and Java (the Kapuas, Mahakam, Barito, Musi). The home water of the transparent glass catfish (Kryptopterus), the black-fin Bagrichthys, many Hemibagrus and Mystus, the walking Clarias, the peat-swamp Ompok and Silurichthys, and the little hillstream Akysis and Glyptothorax. Water ranges from acidic blackwater to clear hill stream.

East Asian rivers

13 species

Temperate East Asia · China, Japan, Korea & Taiwan

The Yangtze, Pearl and Yellow rivers of China, the Amur of the north, and the rivers of Japan, Korea and Taiwan. Home to the East Asian sheatfishes (Silurus asotus and kin), the bagrid Tachysurus and Pseudobagrus, the torrent catfish Liobagrus, and introduced Clarias. Largely temperate, not tropical — several of these are cool-water fish that dislike heat.

North & Central America

40 species

North America · the Mississippi, the Great Lakes & Mesoamerica

The catfish country of the Nearctic: the Mississippi–Missouri–Ohio system, the Great Lakes, the Gulf and Atlantic slopes, and the rivers of Mesoamerica. The family Ictaluridae rules — the bullheads (Ameiurus), the channel and blue catfish (Ictalurus), the flathead (Pylodictis) and the tiny, mildly venomous madtoms (Noturus) — with the tropical Rhamdia reaching down into Central America. A temperate group of hardy, cold-tolerant, mostly large fish.

Europe & western Asia

2 species

The Western Palearctic · the Danube, the Volga & the Ponto-Caspian

The rivers and lakes of Europe and western Asia — the Danube, Rhine, Volga, Dnieper and Ebro, and the Ponto-Caspian basins. The native catfish here is the wels (Silurus glanis), one of the largest freshwater fish in the world, plus the Aristotle's catfish of Greece; American bullheads (Ameiurus) have been widely introduced and now breed across the continent. Cool, temperate water — a small native fauna of very large fish.

Australia & New Guinea

2 species

Sahul · the Murray–Darling, the tropical north & New Guinea

The fresh waters of Australia and New Guinea, where the catfish are chiefly the eel-tail catfishes (family Plotosidae) — Tandanus of the Murray–Darling and the eastern rivers, and Neosilurus and Porochilus across the tropical north and New Guinea. These air-gulping, venomous-spined natives build and guard gravel nests. Water spans cool temperate southern rivers, hot northern floodplains and New Guinea's steep, clear streams.

Other waters

24 species

Worldwide

Catfish whose recorded range falls outside, or spans, the named systems above — including widely-distributed and introduced species, and several little-collected stream catfish known from a single river. Siluriformes is vast and incompletely mapped, and its family-level taxonomy is still moving, so some species sit here until their range is pinned down.

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