Redtail Black Shark (Epalzeorhynchos bicolor)

Every redtail black shark sold today, this one included, is captive-bred — and not by choice of convenience. The species' entire known range was a single river system in central Thailand, and damming, pollution, and the aquarium trade's own historical over-collection combined to wipe out wild populations so thoroughly that the fish is now considered extinct in the wild. What swims in home aquariums worldwide is, genuinely, the only version of this species left. Multiples are possible, but only in a tank large enough for each fish to hold its own patch of real estate out of the others' line of sight — pack them into anything smaller and the territorial disputes never really stop.

Care level: Easy · Temperament: Semi-aggressive, territorial · Max size: ~6" · Min tank: 55 gal (add tank size for each additional fish kept together) · Diet: Omnivore, sinking pellets/veggies