Just vary the diet as mentioned previously. Any good cichlid pellet such as Hikari, NLS, Kens, HBH, etc. Make sure they are vitamin fortified. For more variation, shrimp pellets, krill, raw shrimp, algae wafers etc. Some cichlids will eat algae wafers when they're's hungry enough. With the pellets, try using some containing spirulina and astaxanthan.
As for the band thinning out, sometimes it's just genetics and nothing you can do.