Diagnose Bump On Rainbow

I have 8 rainbow fish, two angelfish, a black ghost knife, and a bristlenose pleco in an 80 gallon aquarium. I completed a fishless cycle six weeks ago and began adding fish three at a time. I conduct 25% water changes, including gravel vacuum, twice a week. One of my rainbow fish developed a bump today. Please advise on diagnosis and recommended treatment.

 

Hello. Welcome to fishlore!
Post another pic tomorrow? If it showed up that fast, it should be big enough to determine the best course of action for you. It may be a cyst or tumor. Or something else entirely. So let’s see if there’s any change by tomorrow. Hoping for the best.

 

HI Gypsy13. Thank you for your response. Here are the next-day photos you suggested I take. Do you (or anyone else) have any recommendations?

 

HI Gypsy13. Thank you for your response. Here are the next-day photos you suggested I take. Do you (or anyone else) have any recommendations?

Does it look noticeably bigger? mattgirl Fanatic Rtessy could y’all compare yesterday’s and today’s pics? Any bigger today?

 

It looks larger and more defined today than it did yesterday.

 

Does it look noticeably bigger? mattgirl Fanatic Rtessy could y’all compare yesterday’s and today’s pics? Any bigger today?

It's definitely a bit bigger than before, and it looks more noticeable.

 

Ok. Still eating ok?

 

It does look larger and more defined, it is a pink circular bulge sticking out about halfway down the body from a section that is yellow

 

Yes. He is eating and swimming normally.

 

Yes. He is eating and swimming normally.

I’m really hoping it’s a cyst. As long as he’s eating and swimming ok, watch closely. Post another picture this evening?

 

Hey Cassandra Marie could you look at this bump for me? I was hoping for another picture. But others are saying there’s a big difference in size from the first pics and the last. Please?

 

Here are photos from day three.

 

Bigger or smaller?

 

No visible change in size in the last 24 hours. The fish continues to eat and swim normally.

 

No visible change in size in the last 24 hours. The fish continues to eat and swim normally.

Good. Watch closely. May have just injured somehow. If gets red around edges, opens up let us know? If you see either of those swab with 3% hydrogen peroxide then get new pics and post? Keep updating ok? Please?

 

Will do. Thank you for the advice.

 

The bump appears to be shrinking. I am cautiously optimistic

 

Watch out for mycobacteriosis.

 

Thank you again to everyone for your help. The bump is basically gone at this point.

 

Thank you again to everyone for your help. The bump is basically gone at this point.

Thank you for the update. Keep an eye on it. And keep posting. Love good updates.