Young fish gather in schools near the water surface, associating with overhanging riparian growth, in particular palmiet (Prionium serratum, a Thurniaceae).

The food is mainly benthic invertebrates; adults are also known to take other edible matter that drifts by, such as terrestrial insects that have fallen on the water surface.

Competition with the Clanwilliam yellowfish (Labeobarbus capensis) – another South African native that was introduced to the redfin's range – has reduced S. erubescens stocks in the Twee River.

The exotic fishes that are harmful to the Twee River redfin are the bluegill (Lepomis macrochirus) and the rainbow trout (Oncorhynchus mykiss), illegally released in its range in the 1990, probably by anglers.

Additional threats include habitat destruction by humans due to water pollution and overuse, and clearing of riparian for orchards.

This is especially harmful, as it deprives the young fish (which are especially under pressure by the introduced species) of their shelter, and allows surface runoff carrying pesticides and fertilizers to pollute the rivers.