Piranhas & Pacus · waters

The waters behind the fish

These characins come from two continents and wildly different waters — a tea-black Amazon tributary where piranhas and silver dollars shoal, the flooded Pantanal that a golden dorado runs, the rapids of the Congo hung with big Distichodus, the weedy Okavango where a pike-characin lurks. 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 darter tetra and a metre-long pacu want such different tanks. Here are the freshwater systems that shaped 853 of the 871 species in this atlas.

The Amazon & Orinoco

605 species

Tropical South America · the Amazon, Orinoco & the Guianas

The greatest characin water on Earth, and the beating heart of this section. The Amazon and Orinoco basins and the Guiana Shield rivers hold the red-bellied and black piranhas (Pygocentrus, Serrasalmus), the tambaqui and other pacus (Colossoma, Piaractus), the silver dollars (Metynnis, Myloplus, Myleus), the striped headstanders (Leporinus, Anostomus), the fanged payara (Hydrolycus), the pike characins (Boulengerella), the wolf fish (Hoplias) and the nano sailfin darters (Crenuchus, Characidium). Warm, soft, often blackwater floodplain — home to both the 3 cm darter and the metre-long pacu, so the size trap is sharpest here.

The Paraná–Paraguay & eastern Brazil

134 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. Piranhas (Serrasalmus, Pygocentrus) and pacus reach their southern limit here, alongside the prized golden dorado (Salminus), the migratory flannelmouth Prochilodus, southern headstanders (Leporinus, Schizodon) and the toothless curimatas. Ranges from tropical floodplain to cool, temperate southern river — several of these characins are not warm-water fish.

The Congo basin

78 species

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

The immense rainforest river of Central Africa — the world's second-largest by discharge — and the richest African-characin water. The Congo and its tributaries (the Kasai, Ubangi, Lualaba) hold the big Distichodus (the six-barred D. sexfasciatus and long-snouted D. lusosso), the little Neolebias and Nannaethiops, the fin-eating Phago and Ichthyborus, the deep-bodied citharinids and the ambush pike-characin Hepsetus. 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. African-characin country: Distichodus, the deep-bodied citharinids (Citharinus, an important food fish), the darter-like Nannocharax, the fin-nipping Ichthyborus and Phago, and the African pike-characin Hepsetus. Warm, seasonally flooded, mostly soft water.

The Nile, Chad & southern Africa

8 species

The Nilo-Sudan & the Zambezi · the Nile, Lake Chad & the southern rivers

The Nile from the Sudd to the delta, Lake Chad, and the Zambezi–Okavango systems of southern Africa — the northern and eastern edge of the African-characin range. Home to Distichodus niloticus and its kin, the deep-bodied Citharinus (a major food fish), the small darter-like Nannocharax, and the pike-characin Hepsetus, which lurks in the weed of the Okavango and Zambezi. From clear headwater to muddy floodplain.

Other waters

18 species

South America & Africa

Characins whose recorded range falls outside, or spans, the named systems above — including widely-distributed species and several little-collected stream fish known from a single river. Serrasalmidae and the minor characin families are still being revised, so some species sit here until their range is pinned down.

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