So I guess its just a wierd thing he does then?
i know this post was a while ago but couldnt resist saying what this behavior is as it may help some of you with the same problemsWhat he does is goes to the top and stick his nose out of the water and when his nose comes back into the water alot of bubbles appear to come from his nose and they stick together. Well if it can't be called a bubble nest then what about a cluster of bubbles that stick together or a bunch of bubbles that are sticking together. So I guess its just a wierd thing he does then?
My Rubber nose goes up the glass and out of the water sometimes, i do get worried but it droppes back into the tank as normal, but there is some bubbles! However i just put that down to normal behaviour.