- Scientific Name: Rasbora trilineata
- Synonym: Rasbora calliura, Rasbora stigmatura
- Common Name: Black Scissortail, Scissorfish, Scissortail, Scissortail Rasbora, Scissortail Shark, Spot-tail Rasbora, Three-lined Rasbora
- Family: Cyprinidae
- Origin: Borneo, Cambodia, Laos, Malaysia, Sumatra, Thailand
- Adult Size: 3.5 inches (8 cm)
- Social: Peaceful schooling fish
- Lifespan: 5+ years
- Tank Level: Top, Mid dweller
- Minimum Tank Size: 20 gallon
- Diet: Omnivore, enjoys live foods
- Breeding: Egg Scatterer
- Care: Easy
- pH: 6.6 – 7.0
- Hardness: 2–12° dGH
- Temperature: 73-78 °F (23-25°C)
Rasbora trilineata, commonly know as the Scissortail Rasbora, originates from the southern Mekong river basin in Cambodia, Laos and Thailand, as well as the Malaysian peninsula and islands of Borneo and Sumatra. Most often found in slow-flowing rivers and swamps in forested areas, Scissortails have also been found in rapidly flowing hillside streams as well as lakes and reservoirs. Currently most specimens sold in the aquarium trade are captive bred rather than wild caught.
Known as the Three-lined Rasbora, or simply as the Scissortail, this fish is a hardy and popular member of the Rasbora family. Slender with an almost transparent body, a horizontal black line runs from behind the gills to the tail. The tail is forked, and bears bands of yellow and black, ending with a band of white at the tip, hence the common name of Three-Lined Rasbora. When swimming and even while at rest, this fish will open and close its tail in a scissor-like fashion, giving rise to the common name it’s best known for, Scissortail.
Adult Scissortails reach a length of approximately 3 and a half inches (8 cm). Males are typically smaller and more slender than females, and when ready to spawn, are more intensely colored. Preferring to live in schools of a half dozen or more, the Scissortail is an active fish that prefers the mid to upper levels of the aquarium. They are quite peaceful and do well in community aquariums.
Scissortails are peaceful gregarious fish that do well in community aquariums. They should be kept with at least a half dozen of its own kind, to bring out their colors and make them feel at home. Other species of Rasboras make excellent companions.
Virtually all Tetra species are good tankmates, as well as Danios, Gouramis, and even larger fish such as Angelfish and Discus. Bottom-dwelling fish such as Corys other catfish species also make good tank-mates. Even livebearing fish such as Guppies, Mollies and Swordtails can be kept with Scissortails. Just keep in mind that some of those species do better in more alkaline water than Scissortails prefer.
Rasbora trilineata requires plenty of open swimming area, and does best in longer tanks. Although not fussy about décor, the most natural setting would be one that includes plants such as Java Moss, driftwood, and rocks of various sizes to mimic a riverbed habitat. Subdued lighting will recreate the typical forested habitat in nature. However, Scissortails will adapt to a wide range of habitats.
Filtration is important, as Scissortails do best in good quality water. They are naturally accustomed to moving water, and would enjoy a current such as that provided by a power head. Water should be soft and on the acidic side. The use of peat or blackwater additives can help replicate the optimum water parameters. Darker substrate is preferred, and the tank should be tightly covered, as Scissortails are prone to jumping.
When bringing this species home, it is wise to match water parameters from the tank they came from, as closely as possible, as they do not adapt well to sudden changes in water conditions. Take care to acclimate them for a sufficient length of time to ensure they are not shocked.
Scissortails readily accept all foods, but prefer live foods whenever possible. In nature their diet consists primarily of insects. However, they will accept frozen foods, freeze-dried foods as well as flake foods. Brine shrimp, Daphnia and any type of worm is an excellent supplemental food, particularly when conditioning before breeding.
Sexual differences in Scissortails are not readily discernible. Males are usually more slender and smaller overall than the female. When ready to spawn, the males will display more robust colors. Females are generally larger and rounder in the belly, particularly when viewed from above.
Scissortails are egg-scatterers that are relatively easy to breed. For best fry yield, a separate breeding tank is recommended, and should be fitted with either a mesh for the eggs to fall through, or spawning mats. Fill the tank about half full of water that is slightly acidic (6.0-6.5) and at a temperature of 77 to 82 °F (25-28°C). Lighting should be minimal, and filtration should be a sponge type filter.
Adults should be conditioned with live foods, such as Bloodworms, Daphnia and Brine Shrimp to prepare for spawning. When the female is full of eggs, place the pairs in the breeding tank. To induce spawning, add small amounts of cooler softer water several times throughout the course of the day. Continue feeding live, or frozen live foods, until spawning takes place.
The breeder pair will make several deposits of adhesive eggs over the spawning medium. Once eggs have been laid, the adults should be removed promptly, as they will readily eat their own eggs. The eggs are sensitive to light and fungus, so lighting should be minimal and the tank should be kept very clean. Frequent water changes are recommended, as well as the use of prophylactic anti-fungals.
After approximately 24 hours the eggs will hatch and initially feed off the egg sack. After another two days the fry become free-swimming and must be fed freshly hatched brine shrimp and other small fry foods