Similar to other members of the species complex with a long, tubular body; flattened on the back in front of the pelvic fins.

[3] G. mcdowalli is mainly olive-brown over the back and sides above the lateral line extending to the top of the head and snout, fading to light brown to cream lower on the body and becoming white on the belly.

Small to medium dark spots and blotches overlay the base colour with some joining up to form uneven vertical bars.

A thin line of gold speckles exists on the middle of the back, running from the nape to the dorsal fin.

Not present in the mid to lower reaches of the Rodger River where introduced brown trout have colonised.