Normal Oranda Behavior

We just got an Oranda a few days ago. I have another goldfish with him, along with a dojo loach. The fantail swims around all areas of the tank. The oranda goes to the top and stays there for a while, and it looks like he is "blowing bubbles". Probably just gulping air, I am not sure.

Is this normal? Here is the info on my aquarium:

28 gallon, with bio filter that filters 200 gph.(should be plenty,right?)
Nitrates- 5ppm
Nitrites- 0
Ammonia-0

I don't have a bubble curtain in there yet(we are putting in one this week). I don't think they are not getting air, there are air bubbles all throughout the aquarium, and the filter seems to keep it really fresh.

It doesn't look like a swim bladder problem, and the other fish are not doing the same thing. Any thoughts?

Thanks,

Cecileew

Orandas generally come to the top to look for food....I use the sinking
type to keep them from taking in gulpfuls of air...I do not want swim
bladder to appear. I like the way they wiggle when they swim....I was
told to always have 2 Orandas as they get lonely and they do tend to
stay together. I also soak their food about 10 minutes to soften it so
they can digest it better. I give them thawed frozen peas with the
outer coat off...they love them.
We really love our babies....
Larry -we have 2 in the pond and 3 in the aquarium