Many other species are considered to be widely
distributed. The morphology between the species of two
different drainage systems was once regarded as
variable forms of one species. Earlier, fish taxonomy was
often based on limited sample sizes and poorly preserved
specimens. Failure to interpret the reason for observed
variability may be ontogenic, geographic, intra or
interspecific; taxonomists conservatively concluded for
intraspecific variability. Fish taxonomy is now to be based
carefully, taking these points into consideration.