Strange growth between gills

[ChanandlerBong]

I noticed a strange, wart-like growth just above my axolotl's bottom right gill. It has the same tonality as his skin, as you can see here https://imgur.com/a/oL1Ty. The pictures are a little blurry, if needed I can try to take clearer ones. His behaviour seems unaffected, he's eating normally, temperature is fine. I'd test the water parameters but I've run out of ammonia/ammonium tests, and my local fish store doesn't open till tomorrow.

Any ideas what this growth might be? How should I proceed?

 

[ChanandlerBong]

I was told that this might be an infection. I wanted to get a second opinion so I don't subject him to unnecessary salt baths.

 

[Cloppy]

Well, I do not think it is fungus. because fungus is normally white and fuzzy looking.

 

[Pinkpsycho]

The photo is bit too blurry for me to see if it's infected of just a funny skin growth. Has it appeared suddenly or did it grow slowly?
It might not be a bad idea to add some salt to your tank as a prevention, but it might brown up your plants.
About 2 or 3 grams per liter would do; axolotls tend to do better in brakish water.
Almond leaves work against infections and fungus as well. One big 20cm leaf per 100 liters.

Hope this helps, or else we'll have to wait for someone more experienced ?