Angelfish - Red Lines/Spots

Question
I have a 10 gallon tank with two angel fish which has been running for just over a month.  I have completed weekly water changes (25%), used treatments for chlorine, stress, etc...  Recently I noticed one of the top fins on one of the fish is turning a redish color and there are red sports forming on the body just below where the top fin attaches.  The fish appears healthy, is eating and swimming as usual.  Any thoughts?

Answer
Hi David,
First of all you are overstocked. A pair of Angelfish alone need a tank of at least 30 gallons. I would recommend upgrading to a tank of at least 30 gallons.
It seems like your Angelfish may have exophthalmia. This is not a disease and is not very common. Its caused by too much waste build up and not enough water changes. This is usually incurable. The only way you can help is to do daily water changes of 30%. They should benefit from this rather than any medications.
Good luck!

Chloe.