The Threadfin Catfish, also known as the Colombian Shark Catfish, is a sleek and active species recognized for its long, elegant fin extensions and silver-gray body. Though often sold as a freshwater fish, it naturally inhabits brackish and even marine environments as it matures, so a gradual increase in salinity is essential for long-term health. It thrives in large, well-filtered tanks with open swimming space, moderate water flow, and hiding areas like driftwood or caves. This species is social and prefers to be kept in small groups. Feed a protein-rich diet of sinking pellets, shrimp, and other meaty foods. Due to its size and energetic nature, it’s best suited for experienced aquarists with spacious aquariums and brackish setups.
Aspect
Details
Scientific Name
Arius seemanni
Common Names
Threadfin Catfish, Colombian Shark, Shark Catfish
Origin
Central and South America (Pacific coastal rivers)
Tank Size
Minimum 100 gallons
Temperature
75–82°F (24–28°C)
pH
7.2–8.5
Water Hardness (GH)
8–20 dGH
Salinity
Brackish to marine (1.005–1.020 SG as adult)
Diet
Sinking carnivore pellets, shrimp, fish, worms
Behavior
Active, schooling, semi-aggressive when cramped
Lifespan
10–15 years
Compatibility
Other large brackish/marine fish; avoid small or slow-moving species
Special Notes
Requires brackish-to-marine water as it matures; needs ample swimming space