From what I've read, mollies are the way to go. And I'm really sorry it went south for you. Hopefully it fixes itself.
Is there anything else you feed him? Or is he live-fish only?
55gPLANTED:Rainbows/Loaches/Garras|30gVIV:Crestie|20gL:Leos|10g:Pearl Fighter|5g:Betta|5gChi:Spark Gourami/Badis|5g:ADF|2.5g:Betta|2.5g:Betta|