What is the scientific name for fish?

The classification of the 28,000 living fish species varies from one to the next; however, all are part of the Animal Kingdom, the phylum Chordata and the subphylum Vertebrata.

Within this subphylum, four different classes contain fish, including the Myxini, Cephalspidmomorphi, the Chondrichthyes and the Osteichthyes. These four classes are divided further into numerous families, genera, species and subspecies.

https://www.reference.com/science/scientific-classification-fish-8fe5761681eb923b

ichthyoid = fish-like.

ichthyology = from the Greek ichthyo- "fish" + logos "reason", the study (scientific) of fishes; the natural history of fishes; a treatise on fishes. Usually restricted to the scientific study of and the resulting knowledge about fishes, particularly in the fields of systematics, taxonomy, anatomy, zoogeography and ecology.