A fish is an animal as science classifies fish as animals.
Fish are a group of animals that are completely aquatic vertebrates that have gills, scales, swim bladders to float, most produce eggs, and are ectothermic.
Sharks, stingrays, skates, eels, puffers, seahorses, clownfish are all examples of fishes.
Fishes and fish do feel pain.
However the pain and the way the fish feels pain is different than how humans and other animals experience pain.
When you catch a fish with a hook they will feel a type of pain but it's not the same as humans would feel the pain.
Neurobiologists have long recognized that fish have nervous systems that comprehend and respond to pain.
Fish, like “higher vertebrates,” have neurotransmitters such as endorphins that relieve suffering the only reason for their nervous systems to produce these painkillers is to alleviate pain.
At the anatomical level, fish have neurons known as nociceptors, which detect potential harm, such as high temperatures, intense pressure, and caustic chemicals.
Fish have numerous nociceptors in their mouths and thus getting hooked is certainly a painful experience for them.
According to science, fish are classed as animals.
Fish belong to one of the six general animal groups which are: mammals, birds, reptiles, amphibians, fish and invertebrates.
Most fish breathe when water moves across their gills.
But if the gills are damaged or water cannot move across them, the fish can suffocate.
They don't technically drown, because they don't inhale the water, but they do die from a lack of oxygen.