[1] Thoburnia rhothoeca has a small mouth with lower lip edges that are nearly triangular.

The fish exhibits sexual dimorphism, and its appearance varies depending on gender.

[3] The male sucker has a narrow red lateral band on it and a long dorsal and ventral fin.

The female sucker has a narrow brown lateral band on it, and a shorter dorsal and ventral fin.

Reasons for the rating include the stable population and the large range of the sucker.