My two kitties loooooove fish. I used to occasionally give them canned fish flavor, so I know what stinky #2s smell like. The smells are worse if their stools are softer than normal, too. There are lots of better quality canned cat food without fish out there, but you won't find those in grocery stores. I used to make sure my cats got a lot of protein by checking the ingredient labels. I chose grain-free because corn, wheat gluten, rice, to me are just "fillers". They need a good, varied sources of protein--chicken, turkey, duck, venison, rabbit, pork, beef, etc. Don't stick to one type...they'll become fish-only addicts! Fish ingredients can cause allergies in cats later on, so I avoid feeding them as a meal now. It is up to you, though. Look up old threads under nutrition to find a huge topic and how it can help cats overall, not just in their poop.
But I totally understand where you're coming from about the smell. It was no picnic for me either.