From Ardrana

Kuo-toa are an ancient race of fish-men that dwells underground and harbors a deep hatred of surface dwellers and sunlight.

A kuo-toan presents a cold and horrible appearance. A typical specimen looks much like a human body, albeit a paunchy one, covered in scales and topped with a fish's head. The huge fish eyes tend to swivel in different directions when observing an area or creature. The hands and feet are very long, with three fingers and an opposing digit, partially webbed. The legs and arms are short for the body size. Its coloration is pale grey, with undertones of tan or yellow in males only. The skin has a sheen from its slimy covering. The color darkens when the kuo-toan is angry and pales when it is badly frightened. A strong odor of dead fish follows it around.

It wears no clothing, only leather harnesses for its weapons and gear. Typically, a kuo-toan warrior carries daggers, spears, shields, harpoons and weighted throwing nets.

Kuo-toa speak the strange subterranean trade language common to most intelligent underworld dwellers. Additionally, they speak their own arcane tongue and have empathic contact with most fish.

Note: Kuo-toa originally appeared in this form in the 2nd Edition Monstrous Manual for the AD&D game from TSR. Their use here is for the purposes of providing context for the campaign only.