Pacamã

Lophiosilurus alexandri is endemic to the São Francisco River drainage in Brazil and is known locally as Pacamã. It is among the most extreme mouth-gape to body-size ratios of any catfish, with a cavernous oral cavity that enables it to ingest prey approaching its own length. Adults exceed 80 cm and are powerfully built.

In the aquarium, the Pacamã is a deceptively still fish — it spends much of its time motionless but can strike with explosive speed when prey ventures close. It requires an enormous tank with minimal tankmates and pristine water quality. Its biological load is very high and industrial-scale filtration is necessary for long-term health.

This species is of great biological interest as an endemic and is protected in parts of its range. Captive specimens should always be sourced responsibly from authorised suppliers.

Water: 20–26°C, pH 6.5–7.5, moderate hardness; very high water turnover required. Tank: Minimum 1500L; bare bottom or coarse gravel, minimal décor, powerful sump filtration. Feeding: Carnivore; large whole fish, prawns, mussels; feed 2–3 times per week. Breeding: No captive breeding documented. Compatibility: Solitary; any co-inhabitant risks predation; keep alone.