Sphaerichthys vaillanti, the Samurai Gourami, is a true blackwater specialist originating from the peat swamp forests of Borneo, Asia. Replicating this specific environment is the key to success. The ideal aquarium is a dedicated biotope with extremely soft, acidic water. Aquarists should use reverse osmosis (RO) water remineralized to a very low level, creating a water hardness between 1-5 dGH. The acidic conditions are achieved by filtering water through peat granules or, more commonly, by adding natural botanicals like Indian almond (catappa) leaves, alder cones, and driftwood. These release tannins and humic substances that stain the water, lower the pH, and provide beneficial anti-fungal properties. The tank should be densely planted with species that tolerate low light and soft water, such as Cryptocoryne, while floating plants like Salvinia or frogbit help to dim the lighting and increase the fish's sense of security.
A gentle current is mandatory, as these are slow-moving fish from still waters. Air-driven sponge filters are an excellent choice, as they provide adequate biological filtration with minimal flow. When it comes to social dynamics, keeping a group of at least six is highly recommended. This allows the fish to form a natural social structure and display more confident behavior. While they can be territorial, any aggression is limited to minor posturing between males, which is easily diffused in a well-decorated tank with plenty of hiding spots. Suitable tank mates are few and must be chosen with extreme care; consider other peaceful, tiny blackwater species like Boraras rasboras or Sundadanio axelrodi. Avoid any fin-nippers or boisterous fish.
Feeding is another challenge, as this species is a micropredator. They should be fed small daily portions of high-quality live or frozen foods such as daphnia, mosquito larvae, grindal worms, or vitamin-enriched brine shrimp. Breeding is famously difficult but fascinating. Unusually for gouramis, the female is the more colorful sex, developing a stunning red and green pattern. After a brief courtship, the female gathers the fertilized eggs into her mouth and incubates them for two to three weeks, releasing a small number of fully formed fry. Raising these tiny offspring requires a ready supply of microscopic foods like infusoria.
