Is this...dropsy?!

[palaeodave]

Came home one night to find a female cherry barb all bloated and spikey-looking. I was off for six days the following morning and she looked like a goner anyway so I got the clove oil out. Did a big water change and had to leave the tank and hope. Got back last night and everyone is perfectly fine, so that's a relief. So, dropsy or something else?

[Jim Powers]

It looks like dropsy to me.

[Diana]

Yes, the scales sticking out like that is typical of dropsy.

[Martin Thoene]

Absolutely. I just lost a female Cherry Barb who blew up bigger than that in 3 days.

Martin.

[palaeodave]

How does that happen? Is something that can spread or does it happen to each fish individually? Have had no further incidents.

[Diana]

Dropsy is a side effect of the internal systems not functioning well.

Normally a fresh water fish works pretty hard to get rid of the excess water that keeps entering their cells. THis is their normal mode of life. Water enters mostly through gills and GI tract. They excrete it through the kidneys. Other areas of the fish are protected by slime coat, so water usually does not enter the cells.
But a fish can get a large skin injury, and water can enter these cells. This would be pretty obvious.

The kidneys and other parts of the water removing, or osmoregulatory system can get infected with bacteria or a virus. When these organs are attacked they can no longer do their job. This is what makes treating Dropsy so difficult: There is no way of knowing what really caused it.

Treatment is usually aimed at 2 issues, and usually does not work.
Treat in a quarantine tank to avoid stressing the other fish.

Adding Epsom salt to the water will help the fish get rid of the excess water, and reduce the amount of water entering their system. You can add other salts to the water, too. Raise the TDS in the tank with NaCl or other things. One recipe:
1 tablespoon of NaCl plus 1/2 tablespoon Epsom salt per gallon. I would dissolve this in some water and add it slowly over the course of the day.

Address the other issue, the cause, with antibiotics. We cannot treat for virus infection, and even if the problem is bacterial the damage may be too far gone anyway. You could kill the bacteria, but the fish still cannot recover. Antibiotics are only a guess as to the cause.

If there is a lot of stress going on, poor water quality or other issues then several fish might show up with Dropsy either at the same time, or within a few days or a week of each other. Even then it is not so much contaigious as similar tank problems causing similar reactions in several fish.
When the tank is well maintained you might just have one fish die with symptoms of Dropsy and it might just be old age, or some weakeness in that fish, and is also not contaigious.

Still, remove the body promptly, many fish diseases are spread by fish eating the dead body, or the disease organisms leaving the dead body after death.

[palaeodave]

Thanks, Diana. That's very clear.