I would only keep it in the fridge for maybe 2 days, in a small sealed container. Alternatively you could pick up a mini ice cube tray (ive seen them at dollar stores) and make up a big batch of the "recipe" and then freeze it. Or you could put it into a ziplock bag, lay it on its side so it spreads out a thin layer, and then freeze it. Then you could just break off a small piece every time u want to feed.
Maybe add some frozen Cyclopeeze to the mix, and some oyster eggs or something very small.
Be careful feeding 3 times a day, in smaller tanks with only 1 fish it can create ammonia problems. I would say 2 times would be just fine.
Cheers
-Diana