Ichthyology

Ichthyology covers a diverse range of body forms and sizes.
top: whale shark and Paedocypris progenetica
bottom: European river lamprey
Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of October 2016, with approximately 250 new species described each year