Acarichthys heckelii help

[rydereric]

I have 10 heckelii and 3 altafrons all very beautiful and some of the heckelii are around a foot long. I have one heckelii that dosent eat spectrum no but everything else does and his colour is much moer light then the other fish. He does eat shrimp though, but im the last couple days he wil go for the shrimp when everyone is feeding but spit it back out, he is still swimming around but when i turn on the light and all the fish wake up he takes longer to get going and kinda sits on the sand with black strips. sooooooooooo i dont no if this helps jus wondering if anyone had any suggestions on what to feed eithother a picky eater or a sick fish. Thanks