There are some hobbyist that do give their fish a fast day. I have always been one to feed everyday, but I think you just need to have some control in how much feed. Overfeeding is one of the biggest mistakes that Tropheus keeper makes. I have done it myself. It is so much fun to watch them eat. But food is one thing you can control, so it is a fine line. I always look to see how the fish I am keeping eat in the wild. Once you see what Tropheus typically eat in a day in the wild, you understand why they eat all day. The algae that they eat is more like a very thin green slime at best. A variety of foods is always best, looks like you are offereing them lots of good things, just becareful not to overfeed. I like to motivate grazing, so if you have lots of algae on your background, then feed them less prepared foods and let them graze, its wonderful to watch this natural behavior.
Tropheus are going to grow their whole life, but they are usually sexually mature at 12 - 14 months old, so around 3"+ or so. I am floored at how big some wild Tropheus are, its hard to get your fry that large.
Enjoy your Tropheus!