A. iridescens and its closest relative A. longipinnis can be distinguished from all other barred species of Acrossocheilus by the following characters: wider (vs. narrower) black vertical bars on the flank in adults, each five to eight (vs. no more than four) scales in width; a horse-shoe shaped (vs. arched) mouth gape; rostral barbel located posteriorly (vs. anteriorly) to a horizontal line through the anteriormost margin of the lower jaw; two postlabial grooves extending anteromedially beyond (vs. away from) a horizontal line through the roots of the rostral barbels.

Known from the from the Red River in northern Vietnam and Yunnan province, southern China, plus the Thái Bình, Sông Kỳ Cùng, Mã and Lam rivers in Vietnam and possibly the Nam Xam and Nam Ma drainages in Laos.

Type locality is ‘Market in Hanoi, Vietnam’.

This species appears to exist in a number of different forms which exhibit differences in colour pattern, morphology, or both, and it’s currently unclear whether all of them are truly conspecific or not although those in the aquarium trade all appear similar to one another.

We’ve been unable to obtain a copy of the original description so it’s not currently possible to provide a detailed diagnosis either, with most recent studi…