There is no difference between black-line flying fox and first-line flying fox, they are regarded as the same fish. Black-line flying foxes and first-line flying foxes have the same body color and habits. Their bodies are slender, and their body length is about 15 cm in adulthood. Their young bodies are taupe, but the fish body has a black line running through the whole fish body. As they grow, the color of the upper part of the body will turn dark green, the middle of the abdomen will be yellow and black, and the lower part of the abdomen will be silver yellow. Both the black-line flying fox and the first-line flying fox have the ability to remove algae, and many breeders will choose to breed several to clean up the algae in the fish tank.

If the breeder wants the black-line flying fox to clean up the algae in the fish tank, it is best not to feed them with food. Because only when they are hungry can they clean up the algae in the fish tank better. In polyculture, breeders should choose fish of similar size. Otherwise, when there is no algae in the fish tank, they will attack other fish.

They are timid and easily frightened. When breeders breed, they need to add a cover above the fish tank, so as to prevent them from jumping out of the tank after being frightened.