Complex sentence: Many fish species that fluoresce are small, group-living, or benthic/aphotic, and have conspicuous patterning that coincides with fluorescent tissue and intra-species behaviors, however the patterning is cryptic at other visual spectra.
Split into simpler sentences: Many fish species that fluoresce are small, group-living, or benthic/aphotic, and have conspicuous patterning. This patterning is caused by fluorescent tissue and is visible to other members of the species, however the patterning is invisible at other visual spectra.