Gas bubble disease
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