Help! Reddish bump/ulcer on fish!

[bettaman]

Feeding my white clouds today I noticed a female has a large reddish bump on her side. It appears to be growing internally as there is no sore on the outside of the fish. What could this be?? No other fish shown any signs or bumps.

[TTman]

if I were u, I would isolate that fish & put in quarantine.

[Kit Walker]

Usually any reddish bump or ulcer is a bacterial infection. Eventually it will enlargen and blister. The fastest remedy is melafix.