The Chocolate Gourami is a rare mouthbrooding fish from Borneo and Sumatra peat swamps. It demands soft acidic water and rewards with fascinating behavior.
Overview
Sphaerichthys osphromenoides is one of the most unusual aquarium fish, a true challenge for the dedicated aquarist. This member of the family Osphronemidae inhabits peat swamps and boggy streams of the Malay Peninsula, Borneo, and Sumatra, where the water is stained dark brown by tannins and has an extremely low pH.
The fish grows to 4–5 cm and can live 5–6 years with proper care. The Chocolate Gourami earns its common name from its distinctive coloration — the body is covered in a deep chocolate-brown hue with several narrow vertical bands of cream or gold. Males are typically slimmer with a straighter lower jaw line. Females are slightly larger, with a more rounded belly and a subtly pointed lower jaw — they are the ones that incubate the eggs in their mouth.
Behaviour is rated 1 out of 5 — this is an exceptionally peaceful, even shy fish that shows no aggression toward tank mates. In the aquarium, Sphaerichthys osphromenoides stay in the middle and lower water layers, preferring shaded areas among plants and driftwood. Watching their unhurried, cautious movements is a genuine pleasure for those who appreciate tranquil aquariums.
Tank Requirements
A group of Chocolate Gouramis requires an aquarium of at least 60 liters. This is not a fish that can be dropped into a typical community tank — it needs specific conditions that closely replicate its natural habitat.
Optimal water parameters: temperature 24–28 °C, pH 4.0–6.0, hardness GH 1–5. Pay close attention to the extremely low pH — this is a key requirement without which the fish will be constantly prone to illness. Tap water in most regions is unsuitable; use reverse osmosis water with appropriate remineralizers or pass water through a peat filter.
The ideal setup is a Southeast Asian peat swamp biotope. Dark substrate, abundant driftwood, fallen Indian almond (catappa) or oak leaves that stain the water a characteristic amber color. Suitable plants include cryptocorynes, bucephalandra, Java moss, and ferns. Floating plants (water lettuce, salvinia, riccia) are essential — they diffuse light and create a sense of security. Chocolate Gouramis do not appreciate bright lighting.
Water flow should be minimal. A sponge filter or a low-power internal filter with adjustable flow is the optimal choice. In nature, these fish live in virtually still water, and strong currents will exhaust them.
Feeding and Diet
Sphaerichthys osphromenoides is an omnivorous fish with a small mouth, which must be taken into account when selecting foods. In the wild, they feed on small invertebrates, insect larvae, and zooplankton.
The dietary foundation in the aquarium should consist of live and frozen foods: brine shrimp nauplii, daphnia, cyclops, micro worms (grindal worms), and small-grade bloodworms. It is on live foods that the fish display their best coloration and activity. High-quality micro pellets and fine flakes can be used as a supplement, but not as the primary diet.
An important note: newly purchased Chocolate Gouramis often refuse dry foods. There is no need to panic — offer live food and gradually introduce dry foods by mixing them with familiar fare. The acclimation process may take several weeks.
Feed 1–2 times daily in small portions. These fish eat slowly and cautiously, so when kept with more active species, make sure food reaches the Chocolate Gouramis as well. Overfeeding is unacceptable — leftover food quickly degrades water quality, to which these fish are extremely sensitive.
Care and Maintenance
The care difficulty of Sphaerichthys osphromenoides is rated 3 out of 5. This is not a beginner's fish, but neither is it impossibly demanding — with adherence to basic principles, Chocolate Gouramis live long and reward their keeper.
The key to success is water parameter stability. Weekly water changes of 15–20 % are mandatory, but new water must be added slowly, preheated to tank temperature, and matched in parameters. Sudden swings in pH or temperature are the primary cause of death in these fish. Ammonia and nitrites must be strictly at zero, nitrates below 20 mg/l.
Keep Chocolate Gouramis in a group of at least 6 individuals. Alone or in pairs, they become skittish, pale, and prone to stress. In a group, they feel confident, display natural behavior, and develop richer coloration.
Pay special attention to disease prevention. Chocolate Gouramis are susceptible to bacterial and fungal infections, especially when water parameters are unstable. Catappa leaves and alder cones in the aquarium not only create a natural environment but also provide mild antibacterial properties. When purchasing new fish, always quarantine them for at least two weeks.
Compatibility
Sphaerichthys osphromenoides is an exceptionally peaceful fish with a behaviour rating of 1 out of 5, ideal for a species-only setup. The best approach is a dedicated tank with a group of Chocolate Gouramis, where one can observe the full range of their social behavior.
If you wish to add tank mates, choose small, calm fish that prefer soft acidic water. Excellent options include Chili Rasbora, Dwarf Rasbora, Harlequin Rasbora, and Glowlight Rasbora. For bottom dwellers, Pygmy Corydoras and Kuhli Loach are suitable choices. Dwarf Otocinclus also make peaceful companions.
Completely unsuitable are: large and active fish, barbs, cichlids, and large gouramis. Even the Dwarf Gourami may prove too pushy a neighbor for the timid Chocolate Gourami. Fast fish will intercept food, and boisterous species will cause constant stress.
Neocaridina shrimp are acceptable tank mates, although they are not always comfortable in very soft acidic water. Amano shrimp are a more versatile option.
Breeding
Breeding Sphaerichthys osphromenoides is rated 3 out of 5 in difficulty. The main distinguishing feature of this species is mouthbrooding, and unlike many other mouthbrooding fish, it is the female that carries the eggs.
To stimulate spawning, prepare a separate breeding tank of 20–30 liters with soft acidic water: temperature 26–28 °C, pH 5.0–5.5, GH 1–3. Place Java moss and fallen leaves on the bottom, and keep the lighting subdued. Condition the breeding pair with live foods for 2–3 weeks beforehand.
Spawning begins with a ritual dance — the pair circles each other, after which the female deposits a small batch of eggs (typically 20–40). After fertilization by the male, the female collects the eggs in her mouth, where she incubates them for 10–14 days. During this period, the female's throat pouch visibly swells and she refuses food.
It is critical not to disturb the brooding female — stress can cause her to swallow or spit out the eggs prematurely. Provide her with hiding places and a calm environment. After releasing the fry, the female is quickly depleted and needs intensive feeding.
The fry are quite large when released from the mouth (approximately 5 mm) and can immediately accept brine shrimp nauplii and micro worms. Growth is slow, and adult coloration is reached at 4–5 months. For the first few weeks, keep the fry in the breeding tank with minimal water changes, gradually increasing the volume.