Chocolate Gourami (Sphaerichthys osphromenoides)

Sphaerichthys osphromenoides, the Chocolate Gourami, is a stunning but delicate labyrinth fish native to the blackwater peat swamp forests of Malaysia, Sumatra, and Borneo. Its rich chocolate-brown body adorned with cream to golden-yellow edging on the scales and fins creates one of the most distinctive and attractive small gourami appearances in the hobby.

The Chocolate Gourami inhabits one of the most extreme freshwater environments on Earth: tropical peat swamp forests where tannin-laden, humic-rich water reaches pH values as low as 3.0–4.0 and has virtually zero mineral content. In the aquarium, replicating these blackwater conditions — extremely soft water, low pH, warm temperature, pristine quality, and significant tannin presence — is both the primary challenge and the key to success with this species.

Chocolate Gouramis are mouthbrooders — unlike most gouramis that build bubble nests, this species (in some populations) incubates eggs in the buccal cavity. The breeding biology varies across populations, adding to the species' complexity.

This is not a beginner's fish. Chocolate Gouramis are sensitive to any water quality lapse, highly susceptible to parasitic and bacterial infections in suboptimal conditions, and require specific water chemistry that many aquarists cannot easily achieve. However, in a species-appropriate blackwater setup, they are long-lived and extraordinarily beautiful fish.

Tank Setup: A 60-litre species or biotope aquarium dedicated to Chocolate Gouramis and similarly delicate blackwater species. Dark fine sand or bare bottom, extensive Indian almond leaves and dried oak leaves, driftwood roots, and dense fine-leaved planting. Extremely gentle sponge filtration through peat. Dim lighting.

Water Parameters: Temperature 26–30°C; pH 4.0–6.5; GH 0–4 °dH; KH 0–2 °dH. Very soft, acidic blackwater is absolutely non-negotiable. Use RO water conditioned with peat and Indian almond leaves. Standard tap water will cause rapid health decline and death.

Feeding: Carnivore leaning. Feed small live and frozen foods: baby brine shrimp, micro worms, Daphnia, small bloodworm. Some individuals accept quality micro pellets after acclimatisation. Feed twice daily in small amounts. Live food is particularly important during initial acclimatisation.

Tank Mates: Species-only or with other blackwater-specialist micro fish: small Boraras, Sundadanio, Parosphromenus species. Avoid any fish that requires different water chemistry. No aggressive or nippy species.

Behaviour: Peaceful but reclusive. Mouthbrooding in some populations. Males and females can coexist peacefully. The fish spends considerable time hovering near plants and wood surfaces.

Health: Highly susceptible to bacterial and parasitic infections, particularly in suboptimal water. Velvet and ich are common issues — preventive conditions (soft, acidic, pristine water) are far more effective than reactive treatment. Quarantine rigorously before introduction.