My cobra guppy male has bubbles in his tail.


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Hey guys my boyfriend has had this cobra guppy for what will be three months on the 29th. He stays active but one day my boyfriend noticed a bubble like thing that was on both sides of the fishes tail and his tail had started to turn orange. He did a partial water change thinking that might help but he then noticed a hole in the fishes tail. It began to get worse and the bubble increased in size and the hole started to get bigger too. As the bubble grew in size it started to produce clear bubbles all on and around the initial site. We did get some Melafix thinking it could be a bacterial infection and it says that it repairs damaged fins and ulcers and open wounds. It recommends to treat for 7 days straight then after 7 days do a 25% water change. It hasn’t been 7 days just yet but my boyfriend said that the bubbles don’t seem to be getting worse. We don’t really know what going on but everything we keep seeing says that the fish has cancer. What can we do? We don’t want to put him down but if that’s what’s best for his life so he’s not suffering, we will do whatever it takes.



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Northeast Ohio
More than 10 years
Hello! I hope we can help you out.

This is very odd, I've never seen anything like this. Lymphocystis is the closest thing to this that I know of, but it still doesn't quite match because it's usually more like white, rough bumps rather than clear, smooth ones like this. It doesn't match the typical appearance of a tumor either. Tumors tend to be either solid in color, or very vascular (full of blood vessels) while these just look like they're filled with fluid.

I'm sure this condition has been documented on some obscure medical journal website somewhere, but it's hard to look for things like that when you don't have a name to go off.

I can say that Melafix probably isn't going to do much. Melafix is just a herbal remedy to treat minor injuries, its it's kind like the fish version of neosporin. You would need stronger antibiotics. But I'm not even sure this is a bacterial infection, it seems more viral in nature. I'd highly recommend starting regular water changes, the best thing for him will be clean water. When I have fish that are sick, I do a water change every other day.

There is the possibility you could aspirate the growths, but that would be pretty difficult to do on a fish this small, especially considering you'd probably have to sedate him to some degree to do it safely.

I hope someone who has spent more time browsing dusty textbooks knows what this is. I'll keep looking for you.

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