How much hp is needed in a fishes bowl?

Bowls make good vases they are not suitable for keeping any kind of live fish in. The basic rules for keeping any fish successfully are :- 1 inch of fish needs at least 1 gallon of water. (3 times this is better). Every tank needs a permanently running cycled filter. :- Every tank needs at least 50% of its water replaced every day. If you stick to the above rules, your fish can survive reasonably well provided you also provide it/them with the correct temperature and other water parameters. If you fail to provide all the above I can guarantee that your fish will be constantly getting sick and will die sooner than it should.