Epalzeorhynchos bicolor (Also known as the Red-Tailed Black Shark) is a popular species of carp from Thailand. These bold-coloured fish grow slowly and have a long lifespan; they reach about 5-6" in maximum length and specimens 10-15 years old are not unheard of. Redtail sharks have a reputation as being aggressive fish, but they have very individual personalities; some are quite laid back and some are quite territorial. We do recommend you avoid species that look similar to them, such as rainbow sharks, siamese algae eaters, certain loaches, etc.
These are juveniles about 1-1.5" long.