I think it would be fattening to feed all the time. I think occasionally would be fine. I think nightcrawlers would be better but it depends on the fish. Some fish will bloat up with too much above ground insect matter. I breed mealworms for my lizards so any time a find a freshly molted mealworm I give it too my fish and they love it. I wouldn't give my fish mealies with the shell. Thier too small and don't have the strong jaws that my lizards have.