One of my oscars have a desease on his head.

[cowbowfishtank]

i have two tiger oscars one about 4 inches and the other 3 inches.. the smaller one has that looks like a fungus on top of his head that i just noticed today. i did a 10% water change Sunday and just noticed it today.. i have 125gallon tank. what should i do?

 

[Mouth-Brooder-Fanatic]

can we have a pic please? it may not be fungus but HLLE which can be cured by raised temps and lots of pwc.
is it what and looking eroded or is it fuzzy? x

 

[steez]

What's the water parameters?

Ammonia, NitrIte, NitrAte, Temperature, pH?

 

[Fishguy2727]

Oscars are extremely prone to HLLE, which is caused by low quality food and water.
What is your usual water change schedule?
What is the nitrate concentration?
What do you feed?
What other fish are in the tank?