Yeah, this is likely.
Our cat only likes fish/fish based foods. We do cook him some fresh fish (well, cooked fresh. Its frozen fish from the store but the stuff without anything added) about once a week and put it over his regular wet food. It makes him happy and he seems to do better in general when he has it.
Maybe I will pick up some non-frozen fish that he likes and see if he likes it more than the frozen stuff.
Try tins of sardines in water. You need to break it up a bit for him but it's better than tuna or other predator fish. I have one cat that won't touch anything fish at all. I've had a lot of cats over the years and never seen a cat refuse canned tuna or fresh fish.
I assume there is a lot of salt in that? He can't handle that with some medical conditions he has. We have offered a very small amount to him before just to see if he would eat it and he wasn't interested. For a shelter cat he is "picky" but deserves it. He had a hard life, he's allowed to be picky now.
Not a lot of salt but it def should not be a daily thing. Whatever he likes. My orange Pumpkin cat who won't eat fish loves burritos. Being in Tucson we have lots of great Mexican food. Him and his sister got nuts if I get a fast food burger.