sorry for not being on for about two months but i havent been able to go online for a while now because of school and studying
i got a new bristlenose pleco last month and hes been doing this weird thing or abut a week. every now and then (s)he rushes up to the surface and releases a few bubbles before getting to the surface, touches the surface of the water and then return to whatever (s)he was doing. i know that plecos can dissove oxygen via their stomachs, but is this normal behaviour?
(s)he seems to be getting along with the other fish, but at first the dojo loaches stalked him/her. now (s)he is getting along with them pretty well, and (s)hes even sleeping with them, sometimes takeing part in pileups.

My friend has a britlenose pleco also and I have noticed it do the same thing (the bubbles and going to the surface).
I have wondered the same thing.

I have been known to own quite a few of these guys,as all my Bristles tend to really enjoy making babies. In fact,I have tanks now that only contain/house Bristles because of that. With mine,I've seen them do that alot.I've also seen them hanging out on floating plants at the top of the aquarium-almost to a point where they're half way out of the water. I think my favorite though,is when I go to clean out the filters,and find 20 or so up in there.
They enjoy a lot of fast moving water/aeration,so I think it has alot to do with it.
My Common Bristles are known for occasionally doing that,along with alot of my Cory cats-especially when I do a big water change.These guys really seem to enjoy that on occasion.I have more than enough filtration,and water params are always kept spot on, so I haven't really ever considered this behavior to be a problem.
Just make sure that your filtration is in tact,along with your water params to rule out any problems with those.
As for keeping them with Loaches,I also own quite a few of them,and recently added one of the bigger male Bristles in with them,because he was picking on the smaller male Bristles.Loaches are like small children,always trying to cause some mischief,so at first they seemed to harass the Bristle.As he adjusted though,he's learned to keep them on their toes,and has actually gotten a little bossy with them at feeding time.
Loaches and Bristles happen to be some of my favorite fish,so I hope you continue with great luck with them.They are so funny to watch!