Sometimes it is easier to have on hand some frozen food rather than try to use live food - you can keep it (hidden) in the freezer, and it comes in convenient squares that are easy to break off and use. Your fish will still benefit from using natural foods, and often it is easier for some fish to get used to eating frozen foods than it is live food. There is also a wider varity available, and of course it will last much longer than live food will.