Kuhlia xenura has a slightly concave dorsal profile of the head in adults, with a large eye.

This species is silver in colour with a dark grey or dusky caudal fin which has a thin black rear margin and frequently shows a pale submarginal band.

While in fresh water they feed mainly on algae, insects, planktonic crustaceans, and foraminiferans, while fish in brackish or salt water eat copepods, amphipods, insects, mollusc larvae, algae, spiders, and annelids.

Medium sized fish, with a total length of 75–150 millimetres (3.0–5.9 in), occur in deeper water at the foot of exposed cliffs, in larger tidal pools, or in rivers or ponds.

[3] For over a century, the name Xenichthys xenurus was overlooked in the literature, and K. xenura was confused with K. sandvicensis by many authors.