Several possibilities come to mind- tumor/cyst, parasite, infection...

I'd definitely QT the fish and try treating for a bacterial infection. Even if bacteria isn't the underlying cause of the wound, there sounds to be a good chance that there is an infection going now, which is what's causing the wound to grow in size.

Salt might be a good option if you don't have any antibiotics handy. Most rainbowfish can handle salt treatment.

 

Thanks for the reply. I do have some bacteria meds available. I will pull him out and put him in quarantine and start treatment. My wife hates it when I have to do that. The quarantine tank should be pretty comfortable for the rainbowfish lol I have some plants I cannot figure out what to do with in there at the moment.

 

Plants are good in a Q-tank. Gives a sick fish a place to hide.

Google some pictures of Lymphocystis. Usually this is more pink-white, not red, and slower growing. Still... at this point check out every possibility.

 

Thanks for the help both Laura and Diana. I do not think it is lymphocystis, the cyst is not on the exterior. It is almost as if he damaged his tail, and it decided to swell. It is a lump under the skin and scales. It is a light pink. I will have him quarantined this eve. And start some anti bacterial treatments. Poor guy. he is a strange one lol. he likes to sit near the edge of the tank when I sit on the couch and watch me. All other times he is running around with my Danios and other Rainbows.

 

Holy crap they are hard to catch. My Danios are easy compared to this because they lack the smarts to hide lol. This little guy has found just about every space to hide in my very thickly planted tank.

 

Ok, so Tonight was the last night of the anti-bacterial treatment. He passed with flying colors. The cyst is no longer getting larger, but it has not gotten any smaller. I am going to leave him in and start anti-internal parasite treatment as well. he does not like that food though lol. he spit it out every time he would catch some of it, then swim to the front of the tank and give me a look like "ok, jokes over where is the real food"

 

LOL

I'm glad the area isn't getting any worse now, at least. Hopefully he'll start improving.

 

Update on the poor little guy. He is still alive and doing very well in the Q tank. Unfortunately the cyst is not getting smaller, it has actually grown another bump on top of the first one. This one looks like the head of a pimple. He is currently being fed medicated anti-parasite foods. (which he does not like) I am on week two of that. Is there anything else I should be trying?

 

It does not sound to me like an internal parasite. Perhaps return to an antibiotic, but switch to a different one. Find one that treats a different group of bacteria.

If you can find the active ingredient in the link below, see what it is good for, then look at other antibiotics and get one that lists different diseases. I am not sure it is bacterial, either, but since it did seem to respond somewhat to the other antibiotics (it quit growing), maybe that is a hint.

http://www.nationalfishpharm.com/diseases.html

 

Well, I do have some other antibiotics on hand, I will start treatment with the other one tomarrow.

This is the best pic I could get of the little sucker. He would taunt me, by swimming up to the camera, and then swim away as fast as he could when I clicked the button lol.

the area is a very light pink, it seems to be deep in the end of his tail. With the exception of the newly discovered "pimple" head that is about the size of the end of a ball point pen, and appears to be a little whitish. Absolutely no change in behavior, still swimming very well. And as hungry as any rainbowfish can be. This thing has been slowly growing over the past month, with the exception of when I had the first treatment in the tank, in which it stopped growing temporarily. I did look at the website you have provided, thank you! The only thing that I did find that sounds somewhat similar is a A sporozoan cyst or lesion, in which it only states that no treatment is available, and gives no further info on what should be done with the fish. I do have one other rainbowfish with a similar dot at the end of the muscles just before the fin, but it has not changed at all during the past month at all.

 

Well, I have tried four different medications on the little guy, and nothing is effective. I have also had to quarantine three other dwarf neons because of a different problem, with one being lost so far. Whatever is going on is only effecting my Dwarf Neons, all of my other fish are healthy and happy. The other Rainbows are not growing very well. They are getting lethargic, and stop eating. They are spending most of their time against the surface of the water, with their tail a bit deeper in the water (at an angle) They get excited for food time, but do not eat. I am at my whits end The last of the Rainbows in my display tank is doing great, eating very active, and about twice the size of the quarantined fish. Water parameters are right in spec for them. 0 ammonia, 0 Nitrites, 10 Nitrates, moderate hard water, and PH at 7.2 After things settle down in the display tank, and either I loose the remaining three in quarantine, or they get healthy again. I will buy a few more from a different LFS and hope they are healthier.

I am getting so frustrated with this.

 

Unfortunately, it could be something that you won't be able to get rid of. Could be that they were harboring something from where they were bred and it has now just come out as they were adjusting to a new environment, etc. I've noticed that the quality of fish in local stores is getting worse and worse, and all sorts of diseases and abnormalities are very common. A lot of times I get myself all excited that I am going out to buy some new fish from one of the several stores I frequent, only to come home empty-handed because many of the fish just looked so terrible. I bought a dozen glowlight danios about a month ago and am down to 4. They looked fine at the store, passed through quarantine fine, but then started to drop like flies when I put them in my main tank. They just seem to be really touchy fish. They seem fine, eat well, not outward signs of distress, but then I'll find another one dead. My other fish don't pay any attention to them and are all very healthy, so I'm at a loss as well. If you are finding that the fish are getting sicker and sicker and nothing is working, you might be best off to euthanize the suffering fish and start from scratch. It can be very hard to identify fish diseases, and it's often too late to do anything if you have to guess at treatment. I feel for ya. It sucks to not know what to do next. Good luck with your fish and hopefully they pull through.

 

update?

Hi,
I realize this is an old thread but I'm wondering what the end of the story was... I have a dwarf neon rainbow with a similar or perhaps the same problem, lump growing out of the fish's side just before the tail. Did he get better? What worked? Thanks!