In the recent revision of the genus Crossocheilus, Ciccotto et al.
Article Revision of the Cyprinid Genus Crossocheilus (Tribe Labeonin...
claim that pigmented anal blotch may and may not occur in Crossocheilus oblongus auctorum plurimorum. The fishes with pigmented anal blotch were determined as Crossocheilus langei previously, another species also with distant anus and anal fin. Nevertheless, all live aquarium specimens with distant anus and anal fin possess pigmented anal blotch. In contrast, pigmented anal blotch vanishes after death. Ichthyologists work with dead material. I wonder whether you know about live Crossocheilus oblongus without pigmented anal blotch.