Matina

The knife livebearer, Alfaro cultratus, is a poeciliid from rivers, streams, ditches and backwaters in Costa Rica, Nicaragua and Panama. The common name comes from a keel of modified, paired scales running from the base of the anal fin to the caudal fin. Exceptionally hardy and adaptable, it can be aggressive, especially towards conspecifics, and breeds readily in the aquarium.