It is of a sandy colour but in the breeding season the colouration changes. The male has a dark blotch at the rear of the first dorsal fin. There is a fairly distinct row of black dots along its side
The Common Goby breeds from March to June, laying its eggs under a shell, which the male then guards until they hatch 11–14 days later. They inhabit sandy-bottomed shallow areas, and in summer may enter estuaries; despite this usual habitat, they can often be found among dense vegetation and in brackish lagoons. Their diet is mostly small crustaceans, skeleton shrimp and worms.