Betta Swimming rapidly around tank

[David Ellsworth]

I purchased a betta from a box store and he spent a few days in his cup with no change. My apartment is cool about 70 degrees so the water was cooler than I'd like for him so I set up a 10 gal tank with a heater, bare bottom, a sponge filter, a few nano dragon stone rocks, and a fake castle for basic cover for him till my planted tank for him cycles. The only light he has is ambient room light. The water in his cup was low 6 pH or high 5 pH. I drip acclimated him before putting him in the tank.

He has been rapidly swimming back and forth along the back glass and sides for about 2 days, almost nonstop. He swims between the heater and the back glass and all over the back glass from bottom to top. At first he was flaring a lot, but not as much now. Is he just seeing his reflection, reacting poorly to the water, or is there other cause for concern? Is it normal and will take a few more days to settle in?

I posted this here because I didn't think it was a disease.

My water is very hard out of the tap, and has chloramine in it so has a little ammonia on set up. I of course used dechlorinator. My parameters are:

• pH = 7.62 
• Hardness/GH = 17 drops (about 309 ppm I believe?)
• KH/Buffer = 3 drops ( 50 ppm)
• TDS = 748 (it was about 700 ppm out of the tap)
• Water Temperature = 78 F
• Ammonia = 0.5 ppm
• Nitrite  = 0 ppm
• Nitrates = 5 ppm

[Mychala]

They love hanging out at the top. It doesn't look like you have anywhere for him to lay out close to the surface. He may just need more chill out areas. But I'm not sure how much of the tank I'm seeing!