Best Filtration For A 15G Tall Betta Tank

[FungusTrooper]

Hey all.
 
I have a tall 15g planted tank with 1 male betta and 2 trilineatus corys. I currently have a small internal filter and a bubble stone in the tank, along with the plethora of plants. I want to provide enough oxygen for the fish (the betta swims about constantly and sometimes gulps for air, but not too much as far as I know, while the corys mainly just scavenge and occasionally swim up to the top of the tank) while reducing surface agitation. I doubt I'll ever breed the betta, but it would be cute to see him building a nest if he wants to.
 
I'm not sure how to reduce the agitation without cutting oxygen, however. I was thinking about a sponge filter, but I have no experience with them. D'ya think I could remove the airstone and still provide enough oxygen?
 
Thanks.
 
PS: Attached picture shows the betta in his "food jail" that I pop him in while the corys eat, otherwise he eats all their food!

 

[Sophie]

the betta swims about constantly and sometimes gulps for air

 
Not sure if you've mentioned this as a concern but Bettas belong to a family of fish called Anabantoids who have what is called a Labyrinth Organ in which they breathe air from the surface as well as through their gills. This applies to fish like Gourami also who belong to the same family so not to worry  

 

[FungusTrooper]

Oh yeah, I didn't mean that as a concern - just a behavior, and relating it to oxygen. I'm actually glad he's so active, I've had bettas before that have just sat around like rocks.

 

[FungusTrooper]

I kinda solved this on my own - I have a low filtration filter and a fine mist bubble stone now. We'll see what happens.
 
Thanks for the advice everyone who posted!