Need new tank ASAP. What tank should I buy?

[meclem3]

My better fish is unfortunately extremely stressed all of a sudden in his tank. After I cleaned his tank with a gravel vacuum today and added new, dechlorinated water at the same temperature of 79°F, he has been charging the glass at all sides because he sees his reflection. I have had him for a week so I am confused as to why he is just now starting to act like this. I tried to cover one of the sides he was mainly freaking out at with several things suggested online (solid black t-shirt, white towel, white printer paper, light blue hand towel) and he continued to flare and knock his head into the glass. I know that with a round tank, reflections can be pretty bad. I have tried several different lighting set ups but none have helped.
Thus, I am buying a new tank after only 7 days.... what type of tank should I get? I want one that will have NO reflection/ mirror effect for the fish.
And for the time being, should I put a solid white or black towel over the side of the tank?

 

[TrueEnvy]

Any angular tank would do. You can even do plastic. Just aim for ~5gallons little less is fine and the more the better. Your fish might just get used to it too, I never had this problem with my, "bowl" you could call itb

 

[V227]

I know of no tank shape that will discourage "Glass Surfing". My biggest offenders were salt water Tangs and a few large fresh water Cichlids. The bad thing about the big cichlids is that when they glass surf, things get knocked over. It's possible that the fresh WC envigorated the Betta making him ready to fight.
I found that my glass surfers never really injured themselves, and the behavior wasn't constant. Turning off the lights usually caused my fish to stop. LFS used to sell Betta mirrors to hang in tanks to instigate the same behavior. Figure that? You might add a tall plant, fake or real, to help break up the Bettas line of sight with his reflection. Don't be hasty, these things usually level out.

 

[Delapool]

Thinking as above as well. I'd give him a few weeks to settle down.