My goldfish is pooing bubbles?

Today my goldfish became quiet lethargic, floating about, and sat still on the bottom a couple if times.
Now he's pooing long string of poo that can contain more than 3 bubbles and these are hanging off him for quite a long time.

I've taken a picture http://i32.photobucket.com/albums/d46/shmooberry/78f61ca3.jpg

Is this normal and is there anything I can do to help him?