[1] This species occurs mainly in coastal rivers of the Atlantic Forest in southeastern and southern Brazil.

[2] These fish inhabit streams with rocky and sandy bottom, mostly in shallows and backwaters up to 30 centimetres (12 in) deep, with slow water flow.

[3] Normally pigmented specimens of S. guntheri have a dark background color on the body and caudal fin, with some light spots and an unpigmented ventral body surface.

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.