Gas Bubble Disease

Question
I have a Tiger which seems to be struggling with Gas Bubble Disease. I have transferred him to my Quarantine tank where he has survived the night tucked away in an artificial hollow log. I am not sure if he will recover however I am looking for the cause in my main tank as I have another tiger barb and a dwarf gourami which at the moment don't seem to be affected as yet. So would like to prevent the same occurrance.
My tank is a 60 litre (24x12x12) I have 1 barb, 1 dwarf gourami, 2 plecs & 6 larger gouramis.
I am wondering if the problem is that I have a 4" strip of air stone (which produces quite big bubbles) virtually under the filter to sheild the view. Could it be that the filter is drawing in the bubbles thus creating an uncomfortable environment for the smaller fish?

Many Thanks
Darren

Answer
Darren,
this is a tuff one, as it is not seen all that often if it is actually GBD.
Gas Bubble Disease is caused by a sudden dramatic change in gas pressure in the aquarium. This can happen by changing too much water at one time or by adding cold water to the fish tank. Gas bubbles form in the fins and skin of the fish. The bubbles look like blisters and are very easy to see. The skin will crackle if you run your finger across it. If not treated in time, gas bubbles in the bloodstream will kill the fish. The treatment is to add alot of aeration to the aquarium. Lights should be left off to minimize stress. If you see alot of bubbles that have already popped, consider adding a general antibiotic to guard against secondary infection, you could use any broad spectrum antibiotic.
Keep me informed and if you have further questions, feel free to ask.