Hi Liz,

It could possibly be neon tetra disease as you said fish are loosing their color in patches. This is caused by the disease killing the muscle tissue. Neon tetra disease does not only affect tetras it also affects other families too including Cyprinids (your redtail shark), cichlids (your angelfish), barbs and rasboras, with tetras being the most susceptible.

Unfortunately there is no cure for neon tetra disease, the best thing to do is do separate/remove the disease fish from the remaining healthy fish. Some literature on the web suggests "Quick Cure", I would visit your local fish store and see what's available.

This disease can be introduced to the tank through live foods such as tubifex or the addition of new fish.

The bleeding around the head area is most likely a secondary bacterial infection. You could try and anti bacterial remedy to try and prevent spread to other fish.

Also check your water quality parameters are optimal for the fish you are keeping, such as pH 6.5 to 7, ammonia and nitrite should be 0ppm. This won't cure the disease but correct water quality definitely help the immune system, in turn help fight off disease/s.

My recommendation would be to remove the diseased fish to a quarantine tank if possible to try and prevent further infection.