The Exclamation Point Rasbora, scientifically known as Boraras urophthalmoides, is a tiny cyprinid fish native to slow-moving, heavily vegetated waters in Thailand, Cambodia, and Laos. It is a popular nano fish in the aquarium trade due to its striking markings, small size, and peaceful nature. Adult Exclamation Point Rasboras reach only about 0.8 to 1 inch (2 to 2.5 cm) in length. They have a slender, translucent golden to reddish body marked by two distinctive black spots: a small dot at mid-body and a larger, round spot at the base of the caudal peduncle. This arrangement resembles an exclamation point, giving the species its common name. Males are more brightly colored, with reddish fins, while females are slightly plumper and paler. A tank of at least 10 gallons is suitable for a small school. Exclamation Point Rasboras should always be kept in groups of at least eight to ten individuals, as they are shoaling fish that feel secure in numbers and display best when in a group. A heavily planted aquarium with fine-leaved plants, floating cover, and subdued lighting will bring out their natural colors. A dark substrate and the addition of leaf litter can help simulate their native blackwater environment. Water parameters should include a temperature range of 72 to 79°F (22 to 26°C), a pH between 5.0 and 7.0, and soft to moderately hard water. These fish are sensitive to water quality and do best in stable, clean conditions with regular partial changes. Feeding Boraras urophthalmoides is straightforward. They are micropredators and prefer tiny live or frozen foods such as daphnia, cyclops, baby brine shrimp, and microworms. They will also take high-quality micro pellets or finely crushed flakes, but live foods help enhance their color and activity. Exclamation Point Rasboras are peaceful and ideal for nano and community aquariums with other small, gentle fish such as other Boraras, pygmy Corydoras, or small shrimp. Avoid housing them with larger or boisterous tankmates. Breeding is possible in captivity but requires attention to water quality and diet. They are egg scatterers and provide no parental care. In a mature, densely planted aquarium, a few fry may survive on their own, but for higher yield, use a separate breeding tank with fine-leaved plants or spawning mops. Fry should be fed infusoria or other microscopic foods until large enough to take baby brine shrimp. Boraras urophthalmoides (Exclamation Point Rasbora) is a tiny, beautiful species perfect for heavily planted nano tanks, admired for its bold markings and lively group behavior.
