The Bristlenose Pleco is one of the smallest catfish, growing to only 3 inches. They are brown, green, or gray with white or yellow spots; some ...Ancistrus is a genus of nocturnal freshwater fish in the family Loricariidae of order Siluriformes, native to freshwater habitats in South America and Panama. Fish of this genus are common in the aquarium trade where they are known as bushynose or bristlenose catfish