First off I can' answer questions on water quality yet. I ran out of testing solutions and then ran out of money. I have two orandas in a twenty gallon tank. I have a HOB filter and a RFUGF both in place over a year now. A red oranda and a red cap. The Red cap is the older of the two and a little bit bigger. Today my daughter noticed a smooth white bump on the wen of the red one. He is still active and swims normally. The red cap doesn't have anything on him and is also behaving normally. Nibble has had wen growths before but they have always been much smaller. Just want to make sure that nothing is wrong with my little guy.