Ok, I've checked all my favorite Betta sites and I'm still not sure what's wrong with Simon.

He's VERY lethargic and is basically staying on the floor of the tank. He comes up for surface air every so often, but isn't doing anything else. No reaction to the mirror or Theo (I thought maybe he was depressed), no obvious ick, doesn't appear 'gold flecked' under a flashlight so no velvet. His fins look pretty normal, but he's just SO inactive and pale. And he's not eating. He hasn't eaten since Monday morning.

I went ahead and treated with some ick/bacterial treatment and have turned off the filtration for now, since I also thought maybe the currents from the filter were stressing him out.

I just don't know what's wrong with him. Please keep little Simon in your thoughts.