Yep they can fish and enjoy it though it makes for a gawd awful mess in the rat enclosures LOL. I tried mine a year or more back with some tiny feeder fish from the pet store. The rats had a blast but there was water and wet bedding (plus bits of fish) everywhere!

Live crickets are a fun hunt for them. In the summer things like frozen grapes, frozen green peas, frozen cranberries make fun rat "icecream".