I. opokiensis Minikh & Andrushkevich, 2017 - Capitanian to Wuchiapingian of Vologda, Russia (Poldarsky Formation)
I. suchonensis Minikh, 1986 (syn: Amblypterina pectinata) - Capitanian to Wuchiapingian of Vologda & Orenburg, Russia (Poldarsky & Malokinelskaya Formations)
Based on an extensive review of tooth morphology, Isadia was a herbivorous fish that predominantly fed on algae. I. suchonensis had teeth adapted for shearing off algae in manner similar to a surgeonfish, I. opokiensis & I. arefievi had teeth adapted for scraping algae off rocks similar to certain cichlids, and I. aristoviensis cropped parts of large algae and submerged vascular plants in a manner similar to rabbitfish. Based on this morphology, Isadia can be divided into two evolutionary lineages: one lineage comprising I. suchonensis→I. opokiensis→I. arefievi, and one lineage comprising just I. aristoviensis.