Finished Tank, Tips?

[Hadexicon]

Well I just finished my tank, I replaced the gravel with sand and everything I'll post the before and after photos, the fish are pretty beat up due to my firemouth BEING A LITTLE **** even my Oscar Toby is messed up.. Might get rid of Felix the firemouth anyway pictures:

Before: http/imgur.com/a/lqmUF

After: http/postimg.org/gallery/hwxdvfwo/

Also, while I'm here my firemouth is being very hostile to the fish mates he is with and it just started like a week ago and my other 4 fish (Oscar 2 plecos and a convict) are getting their find DESTROYED what should I do??

 

[hudsona85]

Very unusual to hear firemouths being the issue... Especially considering what you have in the tank. I have heard of getting some smaller fish like minnows that distracts the more aggressive fish from going after the bigger fish?