“Gas Bubble Disease” is where many gas bubbles form in a fish and literally cause the fish to get the “bends”. This is a “disease” that has probably never occurred in any aquarium.
Water that is very cold can absorb much more air in solution than warm water. Say warm water (25 degrees C.) can have 20 ppm air dissolved in it while cold water (10 degrees C.) can have 40 ppm air dissolved in it. The same is true for pressure, water under pressure can dissolve say 40 ppm air while water at atmospheric pressure can dissolve 20 ppm. The 40 ppm water is called “super saturated”
Living tissues also absorb air into their fluid. If a diver breaths air at a high pressure for half an hour or more the air will dissolve into the tissue fluids at 40 ppm. If the diver ascends too rapidly the air can come out as small bubbles which cause the “bends”. One can die from the bends.
If a fish such as a goldfish were swimming in 10 degree C. water and were suddenly transferred to 25 degree C. water, air can come out in their tissues and produce the bends in the goldfish. A fish swimming in deep water which is suddenly thrust to the surface can also have the bends (although fish have some unique mechanisms to take care of such events).
There was a video by Steenfott Aquatics about a fish breeding operation called Dans Fish. In this operation water is switched out on a 24 hour a day/ seven day a week operation and very cold water (less than 10 degrees C, 50 degrees F) is run through a heat exchanger. A heat exchanger rapidly raises the temperature. Warm water cannot hold as much gas as cold water. So the excess gas will bubble out over a short length of time (roughly thirty minutes).
When the water is put into the aquarium the supersaturated water forms bubbles which attach to everything, including the fish. And Dan’s Fish has decided this is very detrimental to their fish and they have installed some very complicated and expensive mechanisms to deal with it. This is unfortunate. The bubbles are harmless.
In order for bends to occur in any living thing, including fish, the excess gas must be dissolved into the tissues. The only way for a fish to get excess gas into the tissues is for the fish to be under pressure or the fish to be very cold. These two ways are the ONLY ways it can happen. A fish swimming in warm unpressurized water with 40 ppm air dissolved in it (i.e. supersaturated water) will only rapidly absorb air into their tissues to a 20 ppm point, no higher.
The best way to illustrate this is to look at the solubility of salt (sodium chloride) in water. At some pointer around 15% (depends on pressure and temperature) a solution of salt will become “saturated”. You can add more solid salt to the container at this point but nothing will happen. The solid salt will not force “super saturation” of the salt.
The same thing happens with gas. You cannot force rapid supersaturation in a fish by putting a fish in supersaturated water. This is because the gas dissolves into the water or into the fluids in the body. And the amount of gas that dissolves is dependent on pressure and temperature, not on the saturation of the water the fish is swimming in.
Super saturated water will NOT produce super saturated tissues. Only very cold temperatures or high pressures can produce supersaturated tissues. So giving any fish the bends is virtually impossible to do in the aquarium. I can’t even think of a way to do it. And all of the money going into Dan’s Fish to solve this “problem” is wasted money.
Fish can get gas bubbles in their bodies when they get a bacteria that produces gas. This is then blamed on super saturated gas coming out. It isn’t that. It is simply gas caused by a bacteria. In humans this is called ‘’gas gangrene” and is generally fatal.
Most of the Google photos one will find with a “gas bubble disease” search are cardinals with a disease called Dermocystidium. This disease causes fluid filled blisters to form, typically on the eyes. It has nothing to do with gas. The other photos are of goldfish with various forms of “popeye”. Most popeye is fluid filled sacs caused either by genetics, injury, or bacteria.
And most of the literature is incorrect in that cavitating pumps or venturi jets CANNOT cause gas bubble disease. Indeed, they cannot cause supersaturated water.
Return to Symptoms Menu
Aquarium Science Website
The chapters shown below or on the right side in maroon lead to close to 400 articles on all aspects of keeping a freshwater aquarium. These articles have NO links to profit making sites and are thus unbiased in their recommendations, unlike all the for-profit sites you will find with Google. Bookmark and browse!