If you are going away for a week's holiday how do you know that your fish are going to be fed well? The answer is this 7 day fish feeder. It is a pyramid that contains large food pellets and has a secret chamber with Spirulina Algae contained in it so your fish can have a mid week feast. It will feed 15-20 average sized fish in a 50 litre tank for 7-10 days.