Eyespot pufferfish (Dichotomyctere ocellatus) — 2-3cm

Overview

The Eyespot Pufferfish (Dichotomyctere ocellatus), also known as the Figure 8 Puffer, is a smart, charismatic small pufferfish with bold markings and a big personality, best suited to experienced keepers. Native to freshwater and low-salinity waters of Southeast Asia, including the lower Mekong basin (Cambodia), Peninsular Malaysia, and Borneo (Sarawak and Kalimantan), this species inhabits slow-moving rivers and estuaries where it feeds on snails, crustaceans, and other invertebrates. Reaching approximately 7cm in adulthood with difficult care requirements, the Eyespot Pufferfish demands excellent water quality, a specialized diet, and careful tankmate selection. Available to buy tropical fish online uk from Tropical Fish Co, this fascinating species rewards dedicated aquarists with intelligence, personality, and engaging behavior.

Appearance

Adult Eyespot Pufferfish reach approximately 7cm in length, displaying a rounded, elongated body typical of pufferfish species. The species is characterized by distinctive eyespot markings (ocelli) on the body that give rise to both common names, along with a pattern resembling the number "8" when viewed from above. The body is typically yellow-green with brown to black markings, and the species can inflate itself when threatened by gulping water (or air if removed from water). The species has a small, beak-like mouth, prominent eyes, and fin movements that create a hovering, helicopter-like swimming style. Pufferfish lack scales, making them sensitive to water quality and certain medications.

Natural Habitat

This species inhabits freshwater and low-salinity brackish waters in Southeast Asia, including the lower reaches of the Mekong River in Cambodia, Peninsular Malaysia, and Borneo. In the wild, Eyespot Puffers occupy slow-moving rivers, estuaries, and coastal areas where salinity varies with tides and rainfall. The species feeds on hard-shelled prey such as snails and crustaceans, using its fused beak-like teeth to crush shells. The water in these habitats is typically warm (24-28°C), neutral to slightly alkaline (pH 7.0-8.0), and ranges from freshwater to low brackish salinity. Some aquarists maintain this species in freshwater, though low brackish conditions may better support long-term health.

Aquarium Setup

A minimum tank size of 75 litres is suitable for a single Eyespot Pufferfish, with larger aquariums required for multiple individuals or tankmates (though species-only setups are recommended). Structure the aquarium with rocks, driftwood, and hardy plants to create territories and line-of-sight breaks. Provide a sandy or fine gravel substrate and ensure moderate water flow with excellent filtration—pufferfish are messy eaters and produce significant waste. Some aquarists add low levels of marine salt (1-2 teaspoons per 10 litres) to create brackish conditions, though this limits plant and tankmate options. Ensure a secure lid, as pufferfish are curious and may investigate gaps. Avoid sharp décor, as inflated pufferfish are vulnerable to injury.

Water Parameters

This species requires neutral to slightly alkaline water with excellent quality. Target pH between 7.0 and 8.0, with temperatures stable between 24-28°C. Water hardness should be moderate to moderately hard (10-20 dGH). Some aquarists maintain the species in freshwater, while others add low levels of marine salt to create brackish conditions (specific gravity 1.002-1.005). Research both approaches and observe your individual fish to determine optimal conditions. Perform large weekly water changes of 40-50% to maintain pristine conditions, as pufferfish are sensitive to accumulated nitrates. Test parameters regularly using liquid test kits, ensuring ammonia and nitrite remain at zero. Avoid copper-based medications, which are toxic to scaleless fish.

Feeding

Dichotomyctere ocellatus is a carnivore that feeds primarily on hard-shelled prey in the wild. Meaty foods are essential: offer snails (pest snails, ramshorn snails, pond snails), shrimp (whole or shell-on pieces), worms, insect larvae, and other small crustaceans. Hard-shelled prey such as snails are critical for wearing down the species' continuously growing teeth—without appropriate foods, teeth can overgrow and prevent feeding, requiring veterinary intervention. Supplement with occasional frozen foods such as bloodworms, brine shrimp, or krill. Feed once daily, and observe closely to ensure teeth remain at appropriate length. Pufferfish are messy eaters, so remove uneaten food promptly to maintain water quality.

Behaviour

This species displays semi-aggressive, highly intelligent behavior with a bold, interactive personality. Eyespot Puffers are curious, alert, and often recognize their keeper, begging for food and following movement outside the tank. The species can be territorial and may display aggression toward tankmates, particularly other pufferfish or slow-moving fish. Pufferfish are prone to stress in bare or overcrowded environments, and stress can trigger disease or aggressive behavior. The species' intelligence and personality make it a fascinating pet, but also demanding—pufferfish require mental stimulation, appropriate diet, and excellent water quality to thrive. This is not a "beginner" fish despite its small size.

Tank Mates

Due to the species' semi-aggressive temperament and specialized care requirements, a species-only setup is strongly recommended. If tankmates are attempted, only very carefully selected robust brackish-water species in a larger tank (150+ litres) should be considered, such as fast-moving brackish gobies or mollies. Avoid housing with small fish, slow-moving fish, long-finned fish (which will be nipped), shrimp and other small invertebrates (which will be eaten), or fin-nipping or highly aggressive species. The species' specialized dietary and water requirements, combined with potential aggression, make successful community housing extremely challenging.

Breeding

Breeding Eyespot Pufferfish is uncommon in home aquaria and requires excellent water quality, appropriate conditioning, and often carefully managed brackish conditions to trigger spawning. Little reliable information is available regarding captive breeding, and parental care is not typically provided. Aquarists interested in breeding should research specialist pufferfish breeding techniques and be prepared to provide separate breeding and rearing facilities. Most specimens available in the trade are wild-caught or commercially bred in specialist facilities.

Why Buy from Tropical Fish Co

At Tropical Fish Co, we specialize in unusual and challenging species, including fascinating pufferfish like the Eyespot Pufferfish. Our fish are carefully sourced, quarantined, and conditioned to ensure they arrive in excellent health, ready to thrive in your specialist aquarium. We provide expert guidance on diet (including teeth management), water chemistry, and species-only setups to help you succeed with these intelligent and demanding fish. With reliable UK delivery and a commitment to quality, we're your trusted source for freshwater pufferfish and specialist exotic fish uk.