Nina7777
Fish Herder
If your only going to feed frozen food once a week or even twice a week, then one cube would be perfectly fine. I feed one cube to my 29 gallon every day which only has 5 fish in it. and I feed 3 cubes to my 55 gallon every day. so one whole cube once or twice a week will not harm anything and your fish will love it. Just make sure not to feed them anything else that day. 
They can't put that on the bottle if it don't help digestion. False advertising, that is.
/www.geocities.com/im_over_here101