5 pellets 3X a day is 15 pellets a day! that is tooooo much. their stomachs are only as big as their eye and they have short digestive tracts. That will certainly cause problems in the long run.
I would recommend 3 pellets a day and no more. They will always beg like they are starving-its what they do. And we as keepers feel guilty or something and tend to overfeed, maybe because it gives us a chance to be interactive. When people ask am I overfeeding I think they already have their answer.
Metabolism in fish is different than say cats or dogs. Fish can go days between feeding with no detriment to their health. When in doubt, skip a day and give their bellies a chance to clean themselves out.
cheers