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I was changing the water in my tank today when I noticed that my two largest cories have these bizarre-looking fluid sacs near there doral fins. See my profile for the tank, I'm going to the fish store to check the parameters in a bit (I've been unable to afford an entire testing kit for myself).

These fluid sacs are a little [EDIT] larger than pinheads [/EDIT] and are grey-colored. They only seem to be on these two fish. Does this sound like some type of parasite to anyone? Is there some deadly parasite/disease that I don't know about? Other than these fluid sacs, the cories look and act great, they don't even seem to notice them.

Last edited by plasmax000 at 26-Feb-2005 11:36

Sounds very much like Gas Bubble Disease. What country are you in and what kind of environment are you located in - mountainous, farm country, city, etc.

Are you using well water or tap water?

When you do water changes are you putting water directly in from the faucet with something like a python? If so, how much do you change and how often? Do you ever see little tiny bubbles coating things in the tank after a water change?

Another source is a faulty filter that may have a crack in somewhere like the intake or elsewhere. It sucks up air and spits it out into microscopic bubbles.

Have you got an abundance of algae or green water?

Gas Bubble Disease is simply a matter of microscopic bubbles getting into the bloodstream via the gills. You cannot see them so ordinary bubbles seen, no matter how tiny, are not responsible. It is a gas supersaturation.

All you can do is to keep the fish quiet - like dim the lights, and dose the tank with an antiseptic like Melafix and/or Pimafix. This will prevent infection if they should pop. Within time, the bubbles will hopefully reabsorb.

Unfortunately, any gas bubbles that can accumulate under the skin can also create a condition where one or more travels through the blood stream to a vital organ such as the heart or brain. Heart attack or stroke is the end result. So, if any fish should die of sudden death with no other outward signs, save the bubbles, then you may assume that has happened. The reason for keeping the fish quiet and not jarring them is to lessen the chance a bubble will end up in those places.

But, we need to find the source of the hypersaturation or it will continue. So lets continue to discuss those things above.

Scroll down to Gas Bubble Disease to see a pic of a cory with it near the dorsal. Click on the picture to blow it up and compare to yours. Adding an airstone is not recommended in other literature, as they do here.

http://badmanstropicalfish.com/disease.html

Can you possibly get a pic or two? We'd love to have it for our site if it looks like that in the link above.

Last edited by Cory_Di at 26-Feb-2005 12:02

That's exactly what it is!

I feel like an idiot.

"Your cories are probably gravid, plasmax. Do a cold water change and that will probably trigger their breeding." [/sarcasm]

So I do a water change with cold water and what happens? I get gas bubble disease.

This can happen by changing too much water at one time or by adding cold water to the fish tank.

That's what I did, 50% water change (I haven't had the chance to change the water in a while) and with cold water because I was told it would "trigger breeding."

I live in the suburbs of Boston, I use tap water, pouring it into a container and allowing it to mix with dechlorinator before I add it to the tank, but I do remember seeing tiny bubbles coating the sides of the container.

My filter is leaky, and at this time I don't know what to do about it because I don't know where to go to replace the rubber hosing that is very slowly leaking.

I do get some brown algae buildup on the tank sides, but not much.

As for the picture, I'll see what I can do. Thankfully, the bubble on one cory is almost gone. Thank goodness.

Are cories especially susceptible to this disease?

I don't know if scaleless fish are susceptible, in particular. Usually, it is someone with a plec that has it.

If you just used the cold water recently, then you could see ich yet. Ich and Velvet can be brought on by chilling and this can take as little as a 3-4F sudden drop.

Sudden drops of temperature do not induce breeding. Rather, it is the rise in temp that takes place following a drop. This can be simulated by gradually lowering your temp about 1-1.5F daily for several days, leaving it there a few more, then raising it the same amount for several days.

Any water change will simulate a spring rain. Do it as you are raising the temp and .

Watch the fish carefully in the next week and try to keep things dim, quiet and no more shocking water changes. By all means do the water changes, but they should match your temp within 1-1.5F. I'm shocked these fish did not get ich with a 50% change using cold water.

The water had lots of gases and with the bubbles forming on the walls, it was outgassing in the water. When this occurs with fish in the water, some of those outgas into the bloodstream.

I'm glad to hear one has absorbed so soon. Either that or it popped. I strongly suggest the use of melafix and pimafix to prevent infection/fungus. They won't hurt your biofilter and can be dosed together.

Also, if you use a python, make sure the water splashes real good as it goes into the tank. Do not submerge the end of the python on refill. Many gases escape when splashing in. But when the end of the tub is submerged, more gas ends up in the water.

What kind of cories are these? How many do you have? Do you know if you even have females? Is there Java Moss in the tank or other spawning medium?

There are lots of things that can be done to induce breeding. Another one is a change in the photo period. If you reduce your lighting to just 7-8 hours a day on the tank for a week or two, then gradually increase it to 10 hours daily. It signals longer days, which = spring/summer. I bought goldfish that were housed in 8 hours per day of lighting. About 3 weeks after I had them, they were breeding like crazy. The temp was constant, but I had put them on a 12 on/12 off schedule

Last edited by Cory_Di at 26-Feb-2005 20:32

I have five Melenestius cories, and no I'm not certain what gender any of them are nor do I have a spawning medium. The only reason I was trying to induce breeding was because some of the fish started getting so plump it looked like they were uncomfy on the bottom, not because I necessarily wanted baby cories. That's the only reason why I did the cold water change in the first place, and now instead of leaving the cories more comfortable it's made them sick. I feel like such an idiot, it seemed like a bad idea and I wish that I had listened to myself, though I suppose hindsight's always 20-20, isn't it ?

I should clarify, I remember occasionally seeing bubbles on the side of the container I filled with tap water and dechlorinator before adding it to the tank, not always.

Thankfully, no, the bubble isn't popped, it's just drastically shrunk. I checked myself. And like I said, other than those two bubbles everything else about those fish (and the rest of the tank) is perfectly normal. The cories act as if they aren't even there.

I adjusted the shower input on my tank so that it's agitating the surface more. Hopefully that will help. No more crazy water-change ideas!

Aww - don't feel bad. When you ask for help and someone gives you advice, how can you know if it is good or bad. I often take my time and look for multiple opinions. I like to read the debates and then make up my mind.

You may have all females . If you have any males, you should notice that some are much smaller than the others. Females tend to be plump. I believe I have 3 female trilineatus cories. All they do is lay around all day and i've never really seen them breed. My habrosus cories, on the other hand, breed regularly, but I see a size difference between some of them. The females are almost an inch, and the males are almost a half inch. Easy to spot the difference.

I meant to tell you that your pump issue should be fine, if it is just a leak to the outside of the tank. I'm mainly looking for something cracked or loose on the way into the pump where it can suck in water from a place other than the intake. That would need to be corrected ASAP.

I'm so glad to hear the bubbles are reabsorbing so fast. Great ending. If you can, I'd really appreciate some pics and maybe we can use them to write an article on Gas Bubble Disease.

People with deep wells also need to be concerned as there are more gases the deeper it goes.

Slightly off topic, but relevant to your attempts to spawn.

Temperature change should be gradual. Also, let your water stand for around 24 hours before using it if you're trying to persuade your Corys to sapwn, that way any supersaturation of gases will have had time to vent to the atmosphere, and hopefully, this will not recur.

If you're equipped with a digital thermometer like me, then you can implement your Cory water change as follows:

Step 1: change 10% of the existing water for water that is 2°C lower than the tank temperature, as measured with the thermometer. Mine has a probe on a long wire so I can use it to measure both tank and water change bucket with ease.

Step 2: change another 10% the next day, after the temperature has dropped a little, again with new water that is 2°C colder than the existing tank water.

Step 3: Repeat step 2. And do so over 4-5 days until you've implemented your desired temperature change. Changing the temperature by a TOTAL of 2°C over 5 days should not stress your fish unduly.

By the way, the fact that the water is more oxygenated may be a more important stimulus to some Corydoras species than lower temperature. I've had Pandas spawn after a water change that resulted in a 1°C temperature rise. What was more important to my Pandas was that it was new, clean water. And don't forget that Pandas are a cooler-water species that prefer lower temperatures to begin with.

Back on topic: gas embolisms are pretty nasty when they do occur. Usually because they strike unseen, and cause fatal heart failure or brain damage, as Cory_Di said above. In a way, you've been lucky and had visible manifestations allowing you to track the cause of your fishes' discomfort. Most aquarists whose fishes are struck by gas embolisms are left scratching their heads with no visible symptoms: the only way of tracking down the cause in such circumstances is a post mortem dissection, and possibly preparation of histological slides for microscope examination.


Last edited by Calilasseia at 27-Feb-2005 20:02

Last edited by Calilasseia at 27-Feb-2005 20:03

Panda Catfish fan and keeper/breeder since Christmas 2002

Well, a few days have passed and it looks like my cory's making a full recovery! The bubble on his/her fin is almost completely gone! I've seen no bizarre behavior, and it looks like he/she will be just fine.