I personally would never keep a six-line with a mandarin. I have seen to much competion with those two. Try the feeding mysis shrimp mine enjoys that on occasion. 8)
He needs a different home. They really need a good supply of coepods to survive and he also needs a bigger tank that has alot of LR. They are very active fish so if he is sitting still get him out of their until you get things under control. My advice to you is read read read read and study...
I have had both. I had a horrible experience with the Red Sea Products. They do not last very long. I would go with the prizm if you have to. Personaly I would spend the extra few dollars and g o with aqua c remora(hang on type) skimmer. Trust me you dont want to be cheap with these things, if...
