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The Ariopsis seemanni, also called the Columbian Shark, is a remarkable catfish with a shark-like profile and the ability to live in freshwater, brackish water, or marine conditions. Native to the tropical eastern Pacific coast, it is mainly found in estuaries and lower river sections. Despite its popular name, it is not a shark but a marine catfish from the family Ariidae. Keeping it successfully requires a large aquarium, clean highly oxygenated water, and a carefully managed transition to suitable salinity. The species is regularly available in the aquarium trade, but its adult size makes it unsuitable for most ordinary home aquariums.

General description

Ariopsis seemanni is a euryhaline catfish that can tolerate a broad range of salinities during its life. Its streamlined body, deeply forked tail, and dark fins explain the common name Columbian Shark. It is generally peaceful with similarly sized tankmates, but its eventual size and active swimming style must be considered. Juveniles are often kept in freshwater, while adults commonly benefit from brackish to marine water. The dorsal and pectoral spines are strong and can cause a painful injury, so careful handling is essential. This very common trade species is collected from the wild and should be viewed as a long-term aquarium project.

Geographic origin and biotope

The species comes from the tropical eastern Pacific, including coastal river basins and estuaries along Colombia. It occurs where freshwater mixes with seawater, as well as in tidal channels and calmer lower river areas. In Colombia, its natural surroundings include mangroves, mudflats, and wooded banks. Current strength may be moderate to strong in channels, while feeding areas are often calmer. The substrate is mainly sand, mud, and plant debris. In an aquarium, provide clean, strongly oxygenated water and enough open swimming space for this active catfish.

Precise location and local name

In Colombia, Ariopsis seemanni is associated with the Pacific coast, especially estuaries and river mouths. It may also enter the lower sections of coastal rivers depending on tides and salinity. The generic Spanish name bagre is used for several catfish, while Columbian Shark remains the most familiar name in the international aquarium trade. This commercial name does not indicate any close relationship with sharks. Wild individuals mainly occupy shallow margins and tidal channels, where they search through sediments for invertebrates and small fish.

Appearance and physical characteristics

Ariopsis seemanni has an elongated, silver to pale gray body, with a darker back and fins that are often blackish in adults. The broad head carries several pairs of barbels used to locate food in often turbid water. Its deeply forked caudal fin gives it a shark-like appearance and supports efficient open-water swimming. The dorsal and pectoral fins contain rigid, serrated spines, an important feature to respect during capture or transport. Adults can reach approximately 35 cm, sometimes more depending on conditions and the source, so a very large aquarium is required.

General diet

In nature, Ariopsis seemanni mainly eats small fish, crustaceans, worms, and other aquatic invertebrates. It is an opportunistic predator that locates prey with its barbels and sense of smell, particularly during low-light periods. In an aquarium, offer quality sinking pellets, shrimp, fish pieces, and frozen meaty foods. A varied diet supports steady growth, but overfeeding should be avoided because this species creates a substantial organic load. Juveniles often accept several small meals, while adults should receive portions suited to their size and activity. Foods rich in animal protein are important, but they should not be used as a reason to overfeed the fish.

Essential data

• Native river name: Coastal rivers and estuaries of the Colombian Pacific
• Local name used: Bagre
• Origin of the scientific name: The genus Ariopsis and an epithet dedicated to Seemann
• Full-name etymology: Ariopsis means resembling the genus Arius; seemanni honors Seemann
• Common/vernacular names: Columbian Shark, Colombian shark catfish
• Family: Ariidae
• Subfamily: Not indicated
• Name pronunciation: ar-ee-OP-sis - see-MAHN-eye
• Discovery: Albert Karl Ludwig Gotthilf Günther, 1864
• Maximum adult size: Approximately 35 cm
• Water temperature and pH: 22 to 26 °C; approximately pH 6.8 to 8.2, depending on salinity
• Watercourse appearance and surrounding vegetation: Estuaries, mangroves, wooded banks, often turbid water
• Typical tankmates: Similar-sized catfish, robust livebearers, salt-tolerant cichlids, estuarine gobies, juvenile mullet, archerfish
• Temperament and behavior: Generally peaceful, schooling when young, active and opportunistic
• Water depth: Shallow to intermediate coastal zones and channels
• Sexual dimorphism: Limited externally; difficult to determine in juveniles
• Bottom structure and flow: Sand, mud, and plant debris; moderate to strong flow depending on tides

In your aquarium

To succeed with Ariopsis seemanni, provide a very large, covered aquarium with powerful filtration, excellent oxygenation, and plenty of open swimming space. Water parameters should be changed gradually, especially when moving from freshwater to brackish conditions. Use stable décor without sharp edges, and handle the fish carefully because of its spines. A varied meaty diet, regular water changes, and sufficiently large tankmates are essential. Its growth potential makes it a species for aquarists able to provide an appropriate long-term setup rather than a standard community aquarium.