Shark catfish, Tete sea catfish (Ariopsis seemanni) — 9-10cm

Overview

The Ariopsis seemanni, commonly known as the Shark Catfish or Tete Sea Catfish, is a striking, active shark-like catfish that grows large and needs brackish, hard alkaline water and plenty of swimming room. Native to Pacific-draining rivers and estuaries of Central and South America, this species grows to around 50 cm in captivity. Often sold as a freshwater fish when juveniles, adults typically require brackish to marine conditions. At Tropical Fish Co, we supply healthy juveniles with full care guidance to ensure successful long-term keeping.

Appearance and Coloration

Ariopsis seemanni displays a sleek, streamlined body with a silvery-gray base color and a dorsal profile reminiscent of a small shark. The dorsal and pectoral fins have sharp spines that require careful handling. The barbels are long and sensitive. Juveniles show similar coloration to adults, with the silvery sheen intensifying as they mature. Under good lighting, the fish exhibits a metallic shimmer.

Natural Habitat and Distribution

This species inhabits Pacific-draining rivers, estuaries, and coastal brackish waters of Central and South America. Water conditions range from freshwater in juveniles to brackish and marine in adults. The substrate is sand or mud, and the environment is well-oxygenated with moderate to strong current. Ariopsis seemanni is a strong swimmer and active hunter, foraging for small fish, crustaceans, and invertebrates.

Aquarium Setup and Décor

A 500-litre aquarium is the minimum for a single adult. Provide open swimming space, robust filtration, and a gradual transition from freshwater to brackish water as the fish matures. Use sand substrate, driftwood, and smooth rocks. Avoid sharp-edged décor. A secure lid is essential, as this species is a strong swimmer and may jump.

Feeding and Nutrition

Ariopsis seemanni is carnivorous. Offer a varied diet of sinking carnivore pellets, frozen or live shrimp, mussel, earthworms, bloodworms, and chopped fish or seafood. Feed a balanced mix and avoid relying solely on one food type. Feed once daily, ensuring food reaches the substrate. This species is a predatory feeder and will consume any tankmate small enough to be swallowed.

Behaviour and Social Structure

The Shark Catfish is semi-aggressive and primarily a strong swimmer. It is active during the day and patrols the aquarium constantly. This species can be territorial toward conspecifics and may prey on small tankmates. Despite its predatory nature, it is not overly aggressive toward tankmates of similar size.

Compatible Tank Mates

Ideal companions include large peaceful to semi-aggressive fish that tolerate brackish or hard alkaline water such as other robust catfish of similar size, large livebearers (mollies, swordtails), monos, and scats. Avoid housing with small fish, shrimp and other small invertebrates, slow-moving or delicate fish, aggressive fin-nippers, or species requiring soft acidic freshwater.

Breeding in the Aquarium

Breeding is uncommon in home aquaria and typically requires a large, mature group and very specific water conditions. Like other ariid catfish, they are mouthbrooders, with the male carrying the eggs and fry in his mouth until they are free-swimming. Breeding requires specialized setup and is rarely achieved in home aquaria.

Why Buy from Tropical Fish Co

At Tropical Fish Co, every Shark Catfish is quarantined, health-checked, and acclimated to UK water conditions before dispatch. We source our fish from reputable suppliers who prioritize ethical collection and sustainable practices. Our livestock arrives in insulated packaging with heat packs during colder months, ensuring safe transit. With decades of combined fishkeeping experience, our team is available to answer questions about care, compatibility, and gradual salinity transition. Whether you're building a brackish aquarium or expanding an established collection, we're here to support your success. Order with confidence and enjoy premium freshwater fish delivered to your door.