the species he described is the Siamese fighting fish (Betta splendens). In turn, a number of fish species have been named regani in his honour:

Taxon named in his honor

*A Thorny Catfish Anadoras regani (Steindachner, 1908)
*The Dwarf Cichlid Apistogramma regani
*Apogon regani
*A Catfish Astroblepus regani