Is this an abscess?

Hello everyone...and Rayson...

A week or so ago I noticed a small white spot on the right side of Sushi's back. At the time, I tried to tell myself I was just being paranoid...but today I could no longer lie to myself. It has gotten larger.

It appears to be in the fin and is now slightly protruding.

Water parameters: 0 ammonia, 40 nitrate, pH 8.2, temp 66-68 F. My nitrite test just ran out...will be picking up another tomorrow.

Other environmental factors:
I added play sand to the tank 3-4 weeks ago, and even though I rinsed it for three days before putting into the tank, I've had to change out my filter cartridge twice already from all the muck it's been picking up. Despite this, the tank water has been pretty clear since putting the sand in.

Since the filter's been getting clogged up, it's efficiency hasn't been tip-top lately. As a result, I was having ammonia issues until recently. The filter has been taken apart and thoroughly cleaned and ammonia is no longer a problem.

Small water changes have been taking place everyday. Feedings consist of nightcrawlers, red wrigglers, bloodworms, and salamander pellets. I started feeding him the red wrigglers (bought them from Ace) quite recently...possibly a factor?

Nothing has changed in his behavior...hides during the day, swims around at night, and tries to eat anything and everything in sight.

Could this be an abcess? Thank you in advance for the help.

I bought a nitrite test kit and tested the tank today. The test shows 0 nitrite in Sushi's water.

Does anyone have any ideas as to what the white spot could be? Am I over reacting (I really hope so...)?

Sorry I can't help you with what Sushi has on his tail. To my inexperienced eye it doesn't look like an abcess, there doesn't look to be any sign of redness which I would assume there would be if it was an abcess kind of infection.

Hopefully someone with more knowledge of axie skin problems will be on soon. Good luck.

Is the lesion raised or flat? Is is growing? Does it have a definite border? Any ulceration or discharge?

The three photos look like different axies. At this point i would say its unlikely to be an abscess. it could be a regneration issue.

The spot does seem to have a definite border and also seems larger than when I first noticed it a week or so ago. It is also raised slightly. No discharge that I have noticed.

I suppose for now I should just wait to see if anything changes...?

And it probably looks like 3 different axies because I was trying different settings/flash options and my camera is pretty old and crummy

Well its unlikely to be an abscess. if anything, i suspect a benign growth. if you want to be really sure, you can take it to your vet for a fine needle aspirate and cytology. It is minimally invasive and give a lot of useful information. The lesion can also be resected surgically.