The reason why the fishes body adapts to there environment is that there steamline body allows them to cut threw water they also have gills to let them breath under water and there fins to help them swim and they also have little pads.The,
They are most diverse in southeastern Asia, there closest living are characiformes and siluriformes. "They adapt to purely freshwater as the diversity began to spread threw South America basal cypriniforms in Africa, where more advanced cypriniforms survive and coexist with characiforms."
The cyoriniformes are a ray-finned fish, including the caps,minnows , loaches and relatives. This order to contain five to six families over 320 genera, more than 3,250 spices they are from southeastern Asia but there are entire absent from Australia and South America
Oreichthys cosuatis,Oreichthys parvus