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ur factsheet for November 2026: Batasio tengana was once known as Pimelodus tengana, Macrones tengana, Gagata tengana, and Bagrus tengana, and is now named Batasio tengana (Hamilton, 1822). Hamilton first published the original genus name in his 1822 work, "An Account of the Fishes Found in the River Ganges and Its Branches", from the Tista River at Tista barrage, 26°45'10"N, 88°34'11"E, India. The type locality of B. tengana is often given as the Brahmaputra River (e.g. see Eschmeyer, 1998), following the original description, but Hora (1949) narrowed it down to "Gualpara" (=Goalpara in Assam state, Northeast India) based on original notes made by Hamilton.

     Batasio tengana

The author Francis Buchanan FRSE FRS FLS (15 February 1762 – 15 June 1829), later known as Francis Hamilton but often referred to as Francis Buchanan-Hamilton, was a Scottish surgeon, surveyor and botanist who made significant contributions as a geographer and zoologist while living in India. He did not assume the name of Hamilton until three years after his retirement from India. The standard botanical author abbreviation Buch.-Ham. is applied to plants and animals he described, though today the form "Hamilton, 1822" is more usually seen in ichthyology.

In 1822, he published his major work, "An Account of the Fishes Found in the River Ganges and Its Branches". The illustrations were most likely by a young Bengali artist, Haludar, whom Buchanan had trained in scientific illustration since the late 1790s, but about whom little else is known. It stands as one of the earliest and most comprehensive systematic surveys of South Asian freshwater fish, establishing the baseline scientific descriptions for hundreds of indigenous species (such as various barbs, loaches, and catfishes) (Wikipedia).

Assame batasio

Bagrus tengana, Gagata tengana, Macrones tengana, Pimelodus tengana

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Asia: India, Bangladesh, Myanmar and Thailand. Type locality: Brahmaputra River.

7.0cm (2¾ins)

20-25°C (68F-77°F)

Rayed dorsal fin inserted above posterior end of pectoral fin, spine smooth, shorter than head length. Pectoral fin not reaching pelvic fin, spine with 8 or 9 antrorse teeth along inner margin. Pelvic fin reaching anal fin. Anal fin not reaching caudal base. Caudal fin forked, lobes bluntly pointed. Least depth of caudal peduncle 0.8 to 1.6 in its length.

To successfully keep Batasio tengana, you need to replicate a cool, fast-flowing hillstream environment. They are sensitive to poor water quality and lack of oxygen, making them best suited for aquarists with some experience. Use a base of fine sand mixed with smooth, water-worn rocks, cobbles, and larger river stones. Provide plenty of hiding spaces using driftwood, roots, and stone caves. They are naturally nocturnal and shy, so they need secure places to retreat during the day. Small barbs and other temperate species are probably best to keep with them in the higher water column, as they can sustain the lower water temperatures; also, small, peaceful cyprinids (e.g., White Cloud Mountain Minnows, certain Danio or Devario species). Avoid large, aggressive, or overly boisterous fish. Excellent tank mates include other peaceful species that thrive in high-flow, cooler water.

Females become fat with eggs when in good condition, but no spawnings have been known up to date.

Males posses a genital papilla.

Diet: They are carnivores that feed on insect larvae and small crustaceans in the wild. Offer live or frozen foods such as bloodworms, daphnia, brine shrimp, and tubifex worms. They rarely accept dry flakes or pellets right away. You can try introducing sinking carnivore pellets or gel foods once they are settled, but live/frozen food should remain their primary diet.

Anal fin: The median, unpaired, ventrally located fin that lies behind the anus, usually on the posterior half of the fish.
Caudal fin: The tail.
Caudal peduncle: The narrow part of a fish's body to which the caudal or tail fin is attached.
Dorsal fin: The primary rayed fin(s) on top of the body.
Pectoral fin: The paired fins just behind the head.
Pelvic fin: The paired fins, between the pectorals and the anal fins (also referred to as ventrals).

Batasio: From the local (Bengali) name of the fish (batasio or batashi).
tengana: Presumably local Bengali name for this species in India.

Photo Credits

© Beta Mahatvaraj
© Ray Society. Book publisher 2026.
Map: Google Maps. 2026.