I agree with Miguel, feeding sparingly in a sense not to power feed the fish is ok even if the reason behind it is to slow the growth, but if it causes the fish to starve like many lfs do is not ok.
Today I went to the local petsupplies plus, and noticed three juvenile african butterfly fish that looked very underfed. Not trying to be a wise guy or anything, I suggested to the young lady in the fish department to toss in a few small crickets, I know for sure that lfs hire people who have very little experience in what various species of fish need in their diets to survive until someone like you mfk members come in and notice the problem right away. Correct me if I am wrong, but be kind, and helpful by passing along what you may know to the inexperienced fish person.
It's not just lack of knowledge, a lfs near me that I know a few of the staff have been keeping and trading fish for a long time had a little 3" RTC and I have never seen anything like it! The thickest part of its body just behind its head was about the with of a pencil and you could see every indent of the poor things skull, I really was like looking at a skeleton covered in skin, needless to say I don't purchase anything from there anymore
Feed my tank every day tiger barbs get bloodworms and flakes the loaches and eel eat whatever hits the ground I got good filtration also I think I could skip a day to be honest I feed multiple times a day