Butter catfish (Ompok bimaculatus) — XL

Overview

The tropical fish UK aquarist seeking an impressive, graceful catfish will find Ompok bimaculatus, commonly known as the butter catfish, a peaceful but predatory South Asian species best suited to large, dimly lit aquariums with robust tankmates. Native to South Asia and parts of Southeast Asia, including India, Bangladesh, Pakistan, Sri Lanka, Myanmar, and the Mekong Basin, this distinctive silurid catfish displays sleek body shape, elegant movement, and specialized care requirements that make it both rewarding and challenging to keep. Available for sale UK hobbyists should note that this species requires difficult-level care with significant adult size and exacting habitat needs. XL specimens are already substantial and approaching or at adult size of approximately 35cm.

Appearance and Colouration

Ompok bimaculatus displays a sleek, elongated body with smooth, scaleless skin and a flattened head with prominent barbels extending from the mouth. Colouration ranges from silvery-grey to olive-brown on the dorsal surface, fading to cream or white on the ventral side. The name 'bimaculatus' refers to two distinctive dark spots or markings, one on the shoulder and one near the dorsal fin base, though these may fade in older specimens. The fins are translucent to lightly pigmented, and the tail is deeply forked. At XL size, specimens are approaching or at full adult size of approximately 35cm and display well-developed body proportions. The overall appearance is streamlined, elegant, and adapted for midwater cruising.

Natural Habitat

Native to large river systems across South Asia and parts of Southeast Asia, Ompok bimaculatus inhabits slow to moderate-flow rivers, lakes, and floodplains with soft substrates and abundant submerged wood. These environments feature warm, slightly acidic to neutral water with moderate oxygenation and complex habitats. In the wild, butter catfish are nocturnal predators that cruise midwater and surface areas, hunting small fish, crustaceans, and aquatic insects. They are adapted to navigate large, open waters and are commercially important as food fish in their native range. Recreating these conditions with spacious aquaria, subdued lighting, and stable water chemistry supports natural behaviour.

Aquarium Setup

Provide a minimum of 600 litres with ample swimming space and efficient, high-capacity filtration to maintain excellent water quality. Use a soft, fine substrate such as sand to protect the delicate ventral surfaces. Furnish the aquarium with driftwood, smooth rocks, and caves to create hiding places and visual security. Subdued lighting or floating plants help replicate natural low-light conditions and reduce stress. Maintain gentle to moderate water flow, avoiding strong currents. Perform large, regular partial water changes to maintain pristine conditions, as this species is sensitive to poor water quality. Ensure a secure, tightly fitting lid with no gaps, as butter catfish are powerful jumpers.

Diet and Feeding

Ompok bimaculatus is primarily carnivorous, requiring a varied diet of quality sinking carnivore pellets, frozen or live foods such as worms, shrimp, insect larvae, and small fish-based foods. Juveniles may accept smaller live foods, whilst adults require larger portions. Feed in the evening or after lights out, as this species is nocturnal and most active at night. Remove uneaten food after a few hours to maintain water quality. Avoid overfeeding, as catfish can become obese in captivity. A balanced, protein-rich diet supports healthy growth, vibrant condition, and overall vitality. Ensure all tankmates can access food without excessive competition.

Behaviour and Temperament

Butter catfish are peaceful towards similarly sized tankmates but remain predatory and will consume any fish small enough to fit in their mouth. They are primarily nocturnal, spending daylight hours resting among décor or in caves, and becoming active at dusk to cruise midwater and surface areas in search of food. This species is non-territorial and does not display aggression towards other species, though it may outcompete timid fish at feeding time. During the day, they often remain motionless, becoming active as light levels drop. Provide plenty of hiding places to reduce stress and allow the fish to retreat during daylight hours.

Suitable Tank Mates

Compatible with large peaceful fish of similar size, including large gouramis, large peaceful catfish such as plecos, and other calm community fish too large to be eaten. Robust, non-aggressive midwater and upper-level fish may coexist if the aquarium is spacious and well-structured. Avoid small fish, shrimp and other small invertebrates, aggressive fin-nippers, very territorial bottom dwellers, and any tankmate small enough to fit in its mouth. Choose tankmates that appreciate similar water conditions and are not overly competitive at feeding time. A spacious, well-maintained community tank with robust, peaceful companions is ideal.

Breeding

Breeding is uncommon in home aquaria and is not well documented. In nature, Ompok bimaculatus is a riverine spawner, likely requiring seasonal cues such as temperature and water level changes that simulate natural flooding cycles, strong water movement, and large space. Successful reproduction in captivity would require very large quarters, carefully matched pairs, and environmental triggers. There is limited reliable information available on successful home breeding, and most aquarists keep butter catfish for display rather than reproduction. Dedicated enthusiasts with appropriate facilities and extensive experience may achieve success with thorough research.

Special Considerations

This is a large, nocturnal, predatory catfish that requires a spacious, securely covered tank with subdued lighting, soft substrate, and excellent filtration. It is sensitive to poor water quality and elevated ammonia, nitrite, or nitrate levels. Maintain pristine conditions with regular large partial water changes and high-capacity filtration. Ensure a secure lid to prevent jumping, especially during acclimation or disturbances. Plan for significant adult size and ensure long-term space availability. This species is best suited to experienced aquarists with large aquaria, the resources to accommodate a substantial predatory fish, and the commitment to provide exacting care and careful husbandry.

Why Buy from Tropical Fish Co

Tropical Fish Co is a trusted UK supplier of healthy, impressive catfish including Ompok bimaculatus butter catfish. Each specimen is carefully selected for robust health, active behaviour, and excellent condition. Our livestock is quarantined and health-checked before dispatch, ensuring you receive only the finest quality. We provide expert care advice, detailed species information, and ongoing support to help you succeed with specialist fish. With fast, secure delivery across the UK and a commitment to sustainable, responsible fishkeeping practices, Tropical Fish Co is your reliable partner for premium tropical fish and aquatic livestock.