Is a seaturtle a fish

According to Encylopedia Britannica the sea horse is a fish, "any of about 36 species of marine fishes allied to pipefishes in the family Syngnathidae."

seahorses are a genus(Hippocampus) of fishes within the family Syngnathidae, which also includes the pipefishes. There are over 80 species of seahorse.
yes, it is a fish