Is this a disease?

[JackH]

I’ve had these white skirt tetras for 5-6 years, since last year they’ve had these brown blotches on them. I’m not sure if it’s a disease or just aging.

[Colu]

What are your water parameters ammonia nitirtes etc added anything new to the tank resently any rapid breathing hanging near the surface

[JackH]

No nothing unsual, water parameters seem normal. They seem pretty normal

[Colu]

The black marks can be sign your fish is healing from ammonia burn is it possible you had an ammonia spike and missed 

[JackH]

@ColuThanks, I just looked up ammonia burn and it looks the same as what they have. Is there anything I can do to help them recover?

[Colu]

I would add a small amount of aquarium salt 1 table spoon for 10 gallons that will help with Gill function and add essential electrolytes at that level it won't harm your plants  increase water changes and add prime to help detoxify any ammonia   increase testing to make sure you don't miss a spike in the future you can get ammonia test strips they only take 30 second I use ammonia test strips if I see any ammonia I follow up with a liquid test as they are more accurate  

[JackH]

@ColuGreat thanks for the help, I’ll definitely have to get those test strips.