White spot on danios mouth

[Xxmrsthorntonxx]

Hello, I am new to the forum and looking for a bit of advice. I noticed this morning one of my danios has developed a white spot on their lower lip. I was wondering what it could be and how to treat it. I have attached a picture (sorry they are so fast!)

 

[Autumnsky]

Very good chance the water parameters are unsafe.

What are the
Ammonia
Nitrite
Nitrate

pH

TDS

GH/KH

Tank temperature?

If you don't have a test kit, do a couple of 30% - one then the other, back to back, pwc's and see if the fish looks better the next day. You do the water changes that way to make sure the differences in the new tap water and the water in the tank doesn't change to drastically, which can also stress the fish more.

What size is the tank?

How long has it been set up?

Are you familiar with the nitrification cycle? If not the article in my signature link has some excellent basics and helpful hints about keeping fish.