I’m sure we both have cared for and loved animals at some point! There’s nothing wrong with recognizing that a fish can feel pain much like a cat or a dog or a rabbit or a horse.
Can an insect feel pain? What about a mushroom, or a plant? What things are conscious enough to feel pain? I'm genuinely asking because I because it seems arbitrary as to where the line gets drawn. Before the 1980s it was the medical consensus that babies weren't capable of feeling pain even though this is now widely recognized as untrue.
I don't think the line is quite so arbitrary! Virtually all animals (with a few exceptions!) have a central nervous system, which is required to "feel" pain, to my understanding.
The good news is that we can adapt our thinking and behavior in light of new evidence.