Colombian shark catfish (Ariopsis seemanni) care guide

Group

Freshwater fish

Other names

Shark catfish, White-tip shark catfish, Tete sea catfish, Columbian shark catfish, Arius seemanni, Hexanematichthys seemanni

Family

Ariidae (sea catfishes)

Origin

Pacific coast of the Americas from Mexico to Peru, in river mouths, estuaries, mangroves and the sea; young fish move up into fresh water.

Water

brackish

Maximum size

35 cm

Temperature

22–26°C

pH

6.8–8

Hardness

Hard, alkaline water; salt needed as the fish grows

Minimum tank

1000 litres

Care level

expert

Temperament

peaceful

Care

An active, shoaling sea catfish that is sold as a small silvery "shark" with white-tipped fins but grows into a big fish. PlanetCatfish gives a maximum of about 35 cm standard length. Keep a group rather than a single fish – it is a schooling species that is nervous on its own – and plan from the start for a very large, long tank with plenty of open swimming room. The 1,000-litre figure here is our estimate for a small adult group; more is better. Light the tank fairly dimly and leave the middle open; some tall plants or decor around the edges help shy young fish settle. Use a strong filter with good water movement, and a heater guard, as these fish are boisterous swimmers. Salt is the key point. Young fish under about 12 cm can be kept in hard, alkaline fresh water (for example alongside Central American or Rift Lake cichlids), but PlanetCatfish is clear that larger fish must have salt added to thrive. Raise the salinity gradually as the fish grows, to a brackish level and, for full-grown adults, up to marine strength. Fish kept in fresh water for life slowly decline. Keep it at about 22–26 °C, pH 6.8–8. Identification: young sea catfish of several Pacific species look alike, and PlanetCatfish notes that positive ID is based on adults. Fish under about 20 cm are immature; adult females are said to have lighter-coloured fins. Like other sea catfish the fin spines are sharp and can inflict a painful wound, so net carefully and never handle it bare-handed. The species was formerly placed in Arius and Hexanematichthys and is still sometimes sold under those names. Most aquarium fish are wild-caught juveniles. PlanetCatfish lists it as Least Concern on the IUCN Red List (assessed 2007). Selling: our policies require the adult size and long-term tank needs to be stated clearly in the listing. Large fish must travel by a specialist live-animal courier (see the Livestock shipping guide). Sources: PlanetCatfish (planetcatfish.com/common/species.php?speciesid=700). Checked October 2026.

Diet

A true omnivore and a greedy feeder. Small juveniles do well on frozen bloodworm at first; then move them on to lower-protein foods such as sinking catfish tablets and pellets, with frozen prawn, mysis and krill now and then for larger fish. Shop fish are often thin on arrival, so feed little and often until they fill out.

Breeding

Not a realistic aquarium project. Like other sea catfish it is a mouthbrooder: the male carries the large eggs in his mouth. PlanetCatfish describes aquarium spawning as difficult because the fish appear to need a migratory cycle; the one success it mentions involved slowly changing the water from marine to fresh and back again over about a year.

Compatibility and tank mates

Peaceful towards fish it cannot swallow, but it is big, fast and greedy, and will eat small tankmates. While young and in fresh water it can live with robust, hard-water fish of similar size such as larger cichlids. Once salt is added, choose companions that also like brackish water, such as monos, scats and large mollies, and later marine-tolerant species.

Last updated 5 October 2026. Community-edited care guide on Aquatic-Auctions.