Damsel with huge bump that regularly bursts

[Richee]

Hi

I have had my damsel for about 6 years. I recently added 2 new crabs to the tank after quarantining them (did not dump in the old water with them.) I also had to switch to a new salt : From Instant Ocean to Coralife because of a shortage due to the pandemic.

My Damsel now regularly gets a chickpea sized bump on its side. It explodes after about 4 days, leaving an eyeball sized hole in its side. The fish is behaving and eating fine otherwise. The Maroon clown in the same tank is totally fine.

Any thoughts on what this is and how to treat it?

[Sniperhank]

I'm not familiar with anything on that size level, but it isn't that unsimilar to how ich functions. It is a parasite and the fish is sick. Remove to a hospital tank to treat with a copper based medication and possibly some sort of anti parasite medication????

[Richee]

Thank you for the response!

Yes, a parasite is likely the culprit. I thought for awhile that maybe the fish was constipated and this was a new 'exit' . I had this with a lawnmower blenny once, but he died from it within a few days.

My Maroon Clown fish is now struggling to swim and often lays on his side in the sand.

I can't seem to get a hospital tank anywhere right now due to the pandemic, so I am taking both fish out, putting them into a freshwater bath with copper added, leaving them in for 5 minutes, then returning them to the main tank. They seem to do better for a day afterwards.

I'm trying to get an anti-parasitic medication too, but nobody seems to have it right now. Amazon does, but it wont be delivered for more than a week, so I'm worried it will be too late.

[Sniperhank]

Well, can only do so much. So do what you can, sounds like what is being done is working? So once able to fully treat you will likely have success.