Hi, I just bought a female veiltale betta about 4 days ago. For the first night I kept her in the cup she came in, second night I had her in a fair sized vase, and the third night I bought a 1.5 gallon tank (I'm a kid, and I have to buy all the stuff for my betta, so I can't get a 5 gallon). It has a filter, but not a heater, however I live in southwest Florida and my house is warm.
My betta hasn't been active at all; its been behaving really weird lately. It will sit on the bottom of the tank motionless for a few minutes, then rush up to the top to breath air, and go back down. Now it goes to the bottom of the tank and just sits there. For a long. Long. Time. It won't eat, so I don't know if it's bloated or what. And when I try to nudge it, it swims around, gets air from the top, and goes back to the bottom.
I'm thinking it just needs to get used to its tank, but it was very active before. I know betta sleep, but mine "sleeps" all day then. Maybe it really needs a heater? Help!:(

This is my betta, and all it does. It almost looks like it lost color. (By the way, my avatar is NOT my actual betta)

Her tank.