Sphaerichthys vaillanti

The Vaillant's Gourami, also known as the Samurai Gourami, is a small, delicate freshwater labyrinth fish from Asia, prized for its unique build and form. This species is known for its peaceful, yet shy and sedentary nature, making it a captivating addition for the right aquarium setup. They are a shoaling fish and feel most secure when kept in small groups, which helps them display more natural behaviors. However, they can show some territorial squabbles amongst themselves, so adequate space is important. Due to their timid disposition, they should not be housed with large, fast-moving, or aggressive tank mates, as this can cause them significant stress.

As carnivores, their diet should consist of high-quality small live and frozen foods, as they can be reluctant to accept dry or processed options. These gouramis are labyrinth fish, meaning they have a special organ that allows them to breathe atmospheric air from the surface, a fascinating adaptation to their native low-oxygen waters. Given their very specific requirements for soft, acidic water and their sensitivity to environmental changes, they are considered a demanding species to care for. Their keeping is best reserved for experienced aquarists who can provide a stable and meticulously maintained environment.

The Vaillant's Gourami, Sphaerichthys vaillanti, is a specialized species originating from the peat swamp forests and associated blackwater streams of Borneo, Asia. Its natural habitat is characterized by extremely soft, acidic, and tannin-stained water with minimal water flow, dense overhanging vegetation, and a substrate covered in decaying leaves and wood. Replicating this biotope is the key to successfully maintaining them. An ideal aquarium should feature a soft, sandy substrate littered with dried botanicals such as catappa leaves, which help acidify the water and release beneficial tannins that mimic their natural environment. Dim lighting, achieved through floating plants or specialized fixtures, will make the fish feel more secure. Filtration should be very gentle, with a sponge filter or a canister filter with a baffled outflow being excellent choices to avoid strong currents.

This is a shoaling species that should be kept in a group of at least six individuals. While this helps them feel secure, they can establish a pecking order and exhibit territorial behavior. A sufficiently large tank with plenty of visual barriers like driftwood, caves, and dense plantings will help mitigate aggression and allow each fish to claim a small territory. They are slow-moving and tend to inhabit the middle and bottom regions of the aquarium. Consequently, tank mates must be chosen with extreme care. Suitable companions include other small, peaceful, and slow-moving blackwater species like Boraras rasboras or Pangio loaches. Avoid any fin-nippers or boisterous fish, which will easily outcompete the gouramis for food and cause chronic stress.

Feeding is a critical aspect of their care. As micropredators, they thrive on a varied diet of small live and frozen foods such as daphnia, grindal worms, and baby brine shrimp. Many individuals will never accept dried flake or pellet foods, so a consistent supply of appropriate live or frozen options is mandatory for their long-term health. Due to their demanding water-quality needs and specialized diet, they are highly susceptible to poor conditions. Their conservation status in the wild is listed as Vulnerable, primarily due to habitat loss, making captive-bred specimens a more responsible choice and highlighting the importance of dedicated care from experienced hobbyists.

Sphaerichthys vaillanti is a validated species within the family Osphronemidae, which includes all gouramis and fighting fish. It belongs to the Anabantiformes order, a group distinguished by the presence of a labyrinth organ. This complex suprabranchial structure allows the fish to utilize atmospheric oxygen, an essential adaptation for surviving in the hypoxic, stagnant blackwater ecosystems of its native Borneo. Morphologically, S. vaillanti exhibits a compressiform body shape, meaning it is laterally flattened, a common trait among fish that navigate through dense vegetation.

Ecologically, this species fills the niche of a micropredator in the lower to middle strata of its aquatic environment. It subsists on a carnivorous diet of small aquatic crustaceans, insect larvae, worms, and other zooplankton found amongst leaf litter and submerged plants. Its physiology is highly specialized for life in extreme water conditions, specifically water with a very low pH and negligible mineral content (low GH and KH). These adaptations, however, make it exceptionally sensitive to the water chemistry fluctuations, nitrogenous waste, and higher pH levels typical in standard community aquariums. This sensitivity is a primary reason for its reputation as a difficult species in aquaculture.

The genus Sphaerichthys is notable for its unique reproductive strategies, and S. vaillanti is a paternal mouthbrooder. This advanced form of parental care is a key behavioral trait. Its conservation status is classified as Vulnerable (VU) by the IUCN. The primary threats to wild populations are anthropogenic, stemming from widespread deforestation of peat swamp forests for agriculture, particularly for palm oil cultivation. This habitat destruction leads to changes in water chemistry, increased pollution, and outright loss of the specific conditions required for the species to survive and reproduce, making its preservation in both the wild and through responsible captive breeding a matter of ecological importance.

Breeding Sphaerichthys vaillanti is considered very difficult and presents a significant challenge reserved for the most dedicated and experienced aquarists. Success hinges on creating a perfect replica of their natural habitat within a dedicated breeding aquarium. This setup should contain extremely soft, acidic water, often with a pH well below neutral. The tank should be dimly lit and contain abundant cover in the form of fine-leaved plants, driftwood, and leaf litter to provide security.

A group of at least six individuals should be raised together to allow for natural pair formation, which is preferable to introducing a pre-selected pair. Conditioning the group for several weeks with a rich diet of varied live foods is critical to trigger spawning behavior. Sexing these fish can be subtle, but typically, females display more intense coloration and patterning, especially when ready to spawn, while males are generally more subdued in appearance and slightly more slender.

This species is a paternal mouthbrooder. During courtship, the female will release eggs, which the male fertilizes before scooping them into his buccal cavity for incubation. Once the male is holding, he will become reclusive, often hiding in a quiet corner of the tank, and will not eat. The incubation period lasts from one to three weeks, during which it is absolutely crucial that the male is not stressed, as this can cause him to swallow or spit out the brood prematurely. It may be wise to remove the other adult fish from the tank to prevent any disturbances.

After the incubation period, the male will release a small number of fully formed, free-swimming fry. At this point, the male should be carefully removed to a separate tank to recover his strength and prevent him from consuming his offspring. The fry are incredibly small and will require microscopic foods for the first week of life, such as infusoria or specific liquid fry food. As they grow, they can be transitioned to newly hatched brine shrimp and microworms. Pristine water quality is paramount during this fry-rearing stage, as they are exceptionally delicate and sensitive to any pollutants.