Overstocked ?

[MitchM]

Do you have a sanded?
Any detritus piling up behind the rock work or in the sump?

[Madreefer]

To the OP about overstocking. I'm no expert but I've seen a lot of tanks. But really have any of you actually seen fish in the home aquarium actually reach the predicted size that liveaquaria or other sites predict? So IMO it's another issue rather than overstocking. A little more tank and maintenance detail and maybe we can get your issue resolved.