Is this harmful or helpful?

Erin8D

I adore my little betta Charlie, who lives in a sandy 2.5 Gallon tank all by himself. I have a little glass jar in his tank that he likes to look at, and he could easily go in an out if he pleased. I left air in the top of the jar in case he swims in and doesn't remember how to get out. Will the air "go bad"? Or is it safe for him to breath from? Here's a pic.

http://www.tropicalfishkeeping.com/a...cf176_full.jpg

Should I leave the air in it, or let it go out. Please only answer if you know for sure, and not just an opinion :3
I don't mean to be rude, I've just had the hardest time finding the answer!! :/

EDIT: Charlie is in the back right corner looking at his reflection

zof

Let the air out, with out it being circulated by an air pump or some other method the air could turn to a bad mixture from gasses released by the water in a heavy concentration. Not saying that is what would happen but why risk it, if you want put an air stone in there to circulate the air, if nothing else it might look cool.

On a side note he probably doesn't want to go in the glass because hes heard to many stories of other bettas living in something that small

Erin8D

Haha alright, thats what I thought! He'll get over it, eventually(: I actually rescued him from Petco Monday! Haha(: I call all my bettas rescues because they could've gone to homes were the jar IS the tank :c