For most fish, their brains are structured in a way that suggests they aren't conscious in any real way. A good way to kind of think of it would be to try to imagine a time you were on the edge of being black out drunk, but also you can't think in any abstract way, have no real wants, can't think into the future (really can't "think" at all), have much much less awareness of fewer senses. You're memory only operates as brief snippets of feeling matched with flashes of images. The control you feel you have over your body is on par with something like a gag/dry-heave reflex (but probably not as unpleasant). Of course some of this is speculation, but if anything based on the type of fish and lack of formed structures in the CNS, they might not have any experience at all. (anyway Destiny's recent streams with veganism and morality have driven me crazy so I'm going to waste hours of my life addressing some of this and link to a bunch of neurologists and models of consciousness that no one will read, hopefully this weekend)