Graham’s gudgeon, Grahamichthys radiata, is a sleeper of the family Eleotridae, the only member of the genus Grahamichthys. It is found only around New Zealand in shallow coastal waters. Its length is between 1.97 and 2.56 in (5 and 6.5 cm).
Graham’s gudgeon is a small goby-like fish with two separate dorsal fins, a large fan shaped pectoral fin, pelvic fins that are not fused beneath the body like those of true gobies, and a square-cut tail. The head is smooth and bluntly pointed, with a moderately sized mouth that has a protruding lower jaw and bears a number of rows of sharp conical teeth in each jaw. The outer row of teeth consist of enlarged canines and, besides these, males have a pair of prominent fang-like teeth half way back along each side of the lower jaw. There are scales on the hind half of the body only.
Small individuals are almost transparent with faint vertical bands of red, yellow, and black on the body and tail, and dark pigment areas on the head. On larger specimens the head is often dark grey and the trunk is banded with grey-brown. The eyes are blue-black.
These fish swim above sandy or muddy bottoms in shallow coastal areas and are often caught with whitebait.
Illustration by Dr Tony Ayling