I would feed NLS betta pellets.
Personally, I would not feed until you see him poop. I would have him in epsoms salts and if still no poop after a full week on epsoms, I would feed half a shelled pea pulled into little bits at a time and then wait another couple days. If it's growing and you're not feeding then one of a few things is happening.. either this is a tumor of some kind or he has an internal infection. Being able to see what the quality of his poop is will help determine if there's anything wrong going on inside as you will be able to see it in the poop.
To monitor poop you can cup him or put him in a hospital tank without any gravel in the bottom.
That is definitely not normal. Something is up.
Last edited by callistra; 12-14-2012 at 05:40 PM.