Lethargic Betta Fish

[psun03]

I had my betta for about 4 months now. He has always been somewhat active, but I switched to a new larger tank about 2 months ago and most of the time he has been hiding or just floating around. In other words, he is not active at all. I am getting a little concerned about him. He is eating but just floats at the top. From time to time he will swim a bit but he is not very active. The fins look fine. I don't see tail rot or any other kind of issues.

I've been doing some reading and bettas should not be doing that all the time.
The tank is 35 gal bow aquarium (see attached) I have the tank filled halfway. The temperature is set to 75F. I do have a handful (6) cory-dorys and that's it. I do not have numbers for my tank chemistry, I am getting a kit tomorrow.

What are things that I need to look for? What are things that I can do? What are the ideal chemistry numbers?
I sit recommended moving him to another tank? I was thinking of switching him to a tall tank. The tall tank is about 20 gal tall and I was thinking of keeping him by himself. Is that advisable?

 

[ADsnail]

Gee, the little fellow looks sad and lost. If he were my betta, I'd do this:

-Fill the tank to its full capacity, giving him more space
-Put in interesting places for him to explore: arches, shapes, dark places behind decor for him to use as his hidey-hole
-Buy him a Betta Log as his bedroom/retreat
-Buy him a 5-minute mirror for "fight club" daily to stimulate his natural aggression
-75 is well within his temp range, but if you could raise it a bit, to 80, see if he's more active

It's a funny thing, the more hiding places they're given, the more they want to be out in the open and active. Bettas have such intelligent minds, they need things to keep them busy, checking their kingdom and exploring the premises, or they seem kind of depressed and sad with nothing to do.

Others here may query about your water parameters, which is also a good place to start.

 

[m.j.gomez]

Hello, do you have filter & what type of oxygen source do you have in tank? Bettas have a labyrinth organ to breathe surface air but they also have gills to pull oxygen from water. If water not properly oxygenated it might be staying near surface to breath. Plus the have longs fins & it wears them out trying to reach surface.