[3 cats 1 hamste]

I already have 3 kitties n one hamster (see my profile for more info on me n my kitties), even though i have a big house its pretty much the animals domain. The cats are not allowed in my parents, sisters or my room for privasy issues (family of 4 living here) and i was thinking that if i get a small aquarium (like the smaller ones in the pet store, not like thoes lil fish bowls tho) and get a starter kit, wud it be ok 2 have have a fish or 2?