Physical: The green goby is grey-brown in color with a green tint. It has a steeply angled, almost vertical mouth, and pelvic (bottom) fins fused together into a single ray. Green goby have strong sexual dimorphism, meaning that males and females look very different. Females have a yellow head and occasionally a spot on the first dorsal (back) fin. Males have red or orange-tinted dorsal and pelvic fins, and spots on the dorsal and anal (bottom back) fins. Adults grow up to 1.5 in (4 cm).
Habitat: Their range spans from Maryland to Texas, except for eastern Florida. The Barnegat Bay falls outside of this range, so any green goby found here are southern strays. Preferred habitats include mangrove streams, tide pools, creeks and bays, anywhere with fine-grained silt-mud bottom. They also live in sponges, seagrass beds, and oyster reefs.
Feeding: Green goby feed on small shrimps, crabs, and zooplankton.
Breeding: Not much is known about their breeding behavior. One study from the Chesapeake Bay estimated a spawning period from July to September.