S. guntheri forage mostly during the day, though some night activity has also been recorded. These fish graze on microscopic
algae, mostly
diatoms and
green algae growing on rocks and submerged vegetation. They occasionally take
chironomid and
simuliid larvae. Before grazing on a patch with dense sediment, a fish makes wiggling head-down movements to dislodge sediment. When scraping algae off the substrate, it makes vigorous mouth movements, and moves by jerky movements probably related to its mouth alternating between grazing and attaching to the substrate. Grazing leaves characteristic, parallel and elongated marks on the substrate. ==References==