I'm a long time fish keeper but I haven't been active on a forum in a long time. I am hoping you guys might be able to give me some advice.
I have a 29 gallon aquarium, overfiltered, all natural with driftwood, real plants, clay gravel, etc. The tank has currently been set up for almost 5 years continuously. The current inhabitants are 4 swordtails (3 males/1 female) and 1 Angelfish.
I originally bought 4 swordtails (2 males/2 females) and 2 angelfish all at the same time about 2 years ago.
The swordtails reproduced, some died, some babies survived, so now I'm not sure if any are original or if only 1 or 2 of them. The other angelfish died a few weeks after I bought them. The other one has been healthy as a horse from day one.
I change out about 75% of the water every week or every other week, straight tap water. I feed standard fish flakes for tropical fish. I don't add anything else except a little dechlorinator with the water changes. Nothing has been added to this tank since I added these fish two years ago.
Over the past couple months the sole female has been getting these torn up scales just behind her head. Here are some pictures:
I've never had a disease outbreak of any kind in the 5 years I've had this tank up and running.
Any ideas on what this might mean?