Bryconops disruptus
Bryconops disruptus is a small freshwater fish from the iguanodectid family. It lives only in the Rio Negro, a very acidic, blackwater river in South America. The fish is silvery with a relatively deep chest and noticeable teeth. Its name, disruptus, refers to its often incomplete lateral line.
It grows to about 6.4 cm in standard length, making it one of the smaller Bryconops species (the smallest is B. durbinae at about 3.1 cm). It resembles Bryconops caudomaculatus because of a eye-like spot on the tail (caudal ocellus), but B. disruptus is usually a darker silver and has a more consistently incomplete lateral line. It can be told apart from B. caudomaculatus by having 16 precaudal vertebrae (B. caudomaculatus has 17–18). Compared with B. durbinae, B. disruptus has the incomplete lateral line and the tail spot, while durbinae lacks the tail spot.
Taxonomically, B. disruptus was described in 1997. The genus Bryconops was moved from Characidae to the family Iguanodectidae in 2011. There are no widely accepted common names for this species.
Habitat and ecology: the Rio Negro is the world’s largest blackwater river. Water there is very acidic (pH 2.9–4.2), with low minerals and often low dissolved oxygen. These conditions suit many Bryconops species, including disruptus, which shares its habitat with related fishes such as B. collettei and B. colaroja.
This page was last edited on 2 February 2026, at 15:52 (CET).