Have you see my picture?It is either a tumour, fungus or Lymphocystis.
There is no cure for a tumour.
Lymphocystis is a stress virus that normally starts on the tail & fins, and not the gills, so this is unlikely.
Fungus is normally white not yellow.
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How long have you had the fish for?
How long has the fish had the growth?
Did you add anything to the tank in the 2 weeks before this started?
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If you can post a couple more pics showing the fish from the front and back views it will help. Try to get a close up of the growth but from the front as well. It looks like there are red lines feeding the growth and this would indicate a tumour.
SadIt is either a tumour, fungus or Lymphocystis.
There is no cure for a tumour.
Lymphocystis is a stress virus that normally starts on the tail & fins, and not the gills, so this is unlikely.
Fungus is normally white not yellow.
-----------------------
How long have you had the fish for?
How long has the fish had the growth?
Did you add anything to the tank in the 2 weeks before this started?
-----------------------
If you can post a couple more pics showing the fish from the front and back views it will help. Try to get a close up of the growth but from the front as well. It looks like there are red lines feeding the growth and this would indicate a tumour.