Eurycheilichthys limulus is a species of armored catfish endemic to Brazil, where it is found in the upper Jacuí River basin. The habitat at the type locality of E. limulus is a small river about 3–5 metres wide with moderate water current, bottom comprising some rocks but mostly sand and a large amount of marginal vegetation. These fishes live among leaves and stalks. This species grows to a length of 4.8 centimetres (1.9 in) SL.