The body is wide and flat and the front of the carapace and rostrum are often covered with forward facing spines. This shrimp has three pairs of very well-developed antennae (two with the same origins) of almost equal length and is equipped with three pair of walking legs, one pair with very strong pincers that exceed the entire length of the rostrum. The pincers are well-developed and covered in spines. The boxer shrimp is either an orangey red or vivid yellow with white pincers and transparent antennae.
The species is typically nocturnal and in any case prefers the dark, which is why it is often seen in caves. Reproduction occurs between April and November. The Stenopus feeds on worms, small crustaceans, molluscs and fish parasites. This crustacean is in fact a 'cleaner' and fish are quite happy to have it around and even let it pick about in and around their gills.