I agree completely. We cannot declare this xxx fish is a new species unless we make extensive comparision with other species. If we use just 1 -5 specimens for comparision for fish such as bettas we may end up with 2-5 "new" species ^_^.
For the lateral scale count the "standard" procedure new is to count the lateral line scales following the lateral line to the beginning of the tail bone plates, which can be located by bending the tail fin slightly so that the "pit" of the joint is noticed near the tail fin base.
BTW this rasbora is easy to watch underwater with diving mask and snorkel. In many places if you stay still in the water the rasbora may come to nib your hair ^_^.