So… I would suggest steaming the fish unless you can get very fresh seafood. Alternatively, baking it on some parchment.
I’m not sure that raw fish is particularly dangerous on its own- but do check for bones and such. Especially the pin bones. Fish can be an allergen, but if you’ve served it before it should be fine.
I’d say go with whatever they beg for when you’re doing your thing in the kitchen.
Also give the birthday kitty some scritches for me!