On quick trip to northeastern Mexico in September 2007, we collected mollies from various drainages and we also encountered a bunch of interesting crustaceans and fish:

Procambarus cf. acutus cuevachicae, Macrobrachium olfersi, M. acanthurus, Elops saurus, Fundulus grandis, Dormirator maculatus, Herichthys cyanoguttatus, H. carpintis and H. cf. pantostictus. The diversity of Herichthys is just astonishing!