Bottlenose Catfish

Ageneiosus inermis is one of the largest and most imposing members of the Auchenipteridae, found across multiple South American river systems including the Amazon, Orinoco, and Paraná. Its smoothly contoured body, small eyes, and large mouth give it a streamlined, shark-like silhouette that immediately signals its predatory lifestyle. It is a fast, confident swimmer that hunts mid-water for smaller fish and invertebrates.

In the aquarium, Ageneiosus inermis requires very large accommodations — at least 400 litres — with robust filtration and minimal sharp decor that could injure its scaleless body. It is an active, open-water species that does not need substrate hides in the same way as more sedentary catfish, though caves will be used for resting. It must be fed a protein-rich diet of appropriately sized whole or chunked meaty items.

This species demands respect and planning due to its eventual size and strong predatory instincts. It is not suitable for most community setups and is best kept with equally large, robust fish such as large cichlids, other large catfish, or arowanas. Its bold demeanor and impressive silhouette make it a striking centrepiece for specialist large-fish displays.

Water: 22–28°C, pH 5.5–7.5, soft to moderately hard (GH 2–15). Tank: 400 L minimum; powerful filtration; avoid sharp decor; large caves for resting. Feeding: Carnivore; whole fish, large prawns, earthworms, mussel; feed 2–3 times weekly. Breeding: Internal fertilisation as with all auchenipterids; not achieved in home aquaria. Compatibility: Aggressive toward small fish; house only with large, robust species of comparable size.