Boraras briggitae

The Chilli Rasbora, also known as the Mosquito Rasbora, is a stunning, vibrantly colored nano fish that brings a splash of fiery red to any small aquarium. Originating from the slow-moving, dark waters of Borneo, these tiny fish are perfect for aquarists looking to create a peaceful, planted tank. Despite their small size, they are quite active and are best observed in a group. To feel secure and display their brightest colors, they should be kept in a school of at least six individuals, though a larger group is always better.

They are generally peaceful but can be easily intimidated. It's best to house them with other small, calm tank mates like small shrimp or other nano fish. Avoid keeping them with large or overly boisterous fish, which will cause them stress. Feeding is straightforward; as omnivores, they readily accept high-quality crushed flakes, micro-pellets, and enjoy occasional treats of frozen or live foods small enough for their tiny mouths. Their low waste production makes them an excellent choice for well-maintained nano aquariums, especially those with live plants which provide them with cover and places to explore. A gentle water current is preferred, mimicking their natural habitat.

Boraras briggitae, commonly known as the Chilli Rasbora, is a true gem for the discerning aquarist aiming to replicate a Southeast Asian blackwater biotope. Their natural habitat in Borneo's peat swamp forests dictates their ideal care. These environments are characterized by sluggish, tea-colored water, rich in tannins and humic acids from decaying plant material, which results in acidic and exceptionally soft water conditions. To truly see this species thrive and display its most intense crimson coloration, aquarists should aim to create a similar environment. This can be achieved by using a dark substrate, adding botanicals like catappa leaves, alder cones, or driftwood to release beneficial tannins, and maintaining a gentle, low-flow filtration.

Dense planting is highly recommended, not just for aesthetics, but for the well-being of the fish. Plants like Cryptocoryne, Java moss, and floating vegetation provide crucial cover, reducing stress and encouraging more natural social behaviors. As shoaling fish, their behavior changes dramatically with group size. A minimal school will often be shy and reclusive, while a larger shoal of ten or more will become bolder, with males actively sparring and displaying for females. Their 'active' nature is best described as bustling rather than frantic; they explore the top and middle water columns with purpose.

When considering tank mates, micro-predation must be considered. While peaceful towards fish, they may prey on the tiniest of shrimplets. Ideal companions include other micro-rasboras, pygmy corydoras, otocinclus catfish, and adult dwarf shrimp (Neocaridina or Caridina species). Aggressive or significantly larger fish must be avoided as they will easily outcompete the Chilli Rasbora for food and cause chronic stress.

Dietarily, their omnivorous nature and small mouths require appropriately sized foods. A varied diet is key to their health and five-year lifespan. While they will consume high-quality micro-pellets and crushed flakes, their health benefits immensely from supplementation with live and frozen foods such as baby brine shrimp, daphnia, and cyclops. This varied diet is also a crucial component for conditioning them for breeding. Breeding is considered moderately difficult; they are continuous egg-scatterers, and for fry to have a chance of survival, a dedicated, mature breeding tank with dense mosses is often necessary as the parents provide no care and will predate on their own eggs and fry.

Boraras briggitae (Vogt, 1978) is a diminutive cyprinid belonging to the family Danionidae. Its genus, Boraras, is an anagram of Rasbora, a taxonomic distinction highlighting a key morphological difference: a higher count of abdominal vertebrae compared to caudal vertebrae, which is the reverse of the ratio found in the genus Rasbora. This species is endemic to the peat swamp forests and associated blackwater stream networks of southwestern Borneo, Indonesia.

The ecological niche occupied by B. briggitae is characterized by highly acidic (pH as low as 5.0), soft (low dGH), and tannin-stained lentic waters with minimal flow. These conditions are a direct result of the decomposition of vast amounts of organic material, primarily leaf litter and peat substrate. The species' physiology is well-adapted to this nutrient-poor environment, exhibiting low oxygen consumption and a low metabolic rate, which corresponds to its minimal bioload contribution in a closed aquatic system. Its classification as a biofilm consumer indicates a feeding strategy that involves grazing on microorganisms, aufwuchs, and small invertebrates found on submerged surfaces and plant matter, supplementing its omnivorous diet.

Socially, B. briggitae is an obligate shoaling species. In situ and in captive environments, complex social hierarchies and behaviors, including ritualized sparring among males, are observed, particularly in larger population groups. Stress responses are readily triggered by the presence of significantly larger or more active heterospecifics, a factor critical for consideration in multi-species aquarium management.

Reproductive strategy is that of an egg-scattering, continuous spawner. No parental care is exhibited post-spawning. Successful gametogenesis and spawning behavior in captivity are strongly correlated with the replication of its native water chemistry, particularly low pH and hardness. While its IUCN Red List status is currently 'Least Concern' (LC), localised populations are vulnerable. The primary threat to B. briggitae is habitat degradation due to widespread deforestation for agriculture, particularly palm oil plantations, which alters the unique blackwater chemistry essential for its survival and reproduction.