Pacman Catfish (Lophiosilurus alexandri)

Pacman Catfish — Lophiosilurus alexandri

The freshwater frog with a predator’s bite

The Pacman Catfish is one of the most unusual ambush predators in the aquarium world. With a wide, flattened body and an oversized mouth that seems to take up half its frame, Lophiosilurus alexandri looks more like a giant aquatic frog than a traditional catfish. Earth-toned camouflage patterns allow it to blend perfectly into sandy riverbeds — until it decides to move.

Native to the São Francisco River basin in Brazil, this species is built for patience. It rests motionless on the bottom, partially buried in sand, tracking vibrations and movement above. When prey drifts too close, the Pacman launches upward and inhales it in a single powerful gulp. Feeding time is fast, sudden, and unforgettable.

Growing to 16–24+ inches, this is a heavy-bodied predator that prefers width over speed. It doesn’t cruise the tank — it claims a section of substrate and waits.

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Aquarium Setup

• Minimum Tank Size: 180 gallons (wide footprint preferred over height)

• Substrate: Fine sand (essential for natural behavior)

• Flow: Low to moderate

• Décor: Open sandy areas with minimal sharp décor

• Lighting: Dim to moderate

• Cover: Secure lid recommended

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Tank Mates

Best kept alone or with very large, robust species:

• Large armored plecos

• Some large bichirs (case dependent)

• Very large, non-aggressive fish that stay mid-to-upper water

Anything small enough to fit in its mouth will eventually be eaten.

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Water Parameters

• Temperature: 74–82°F (23–28°C)

• pH: 6.0–7.5

• Hardness: Soft to medium

• Filtration: Strong biological filtration

• Water Quality: Clean, stable conditions required

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Diet

Strict carnivore:

• Fish fillet

• Shrimp and prawn

• Worms

• Appropriately sized whole fish (frozen/thawed recommended)