Can you please advise? My fish developed a protuberance on his head 3 weeks ago. I kept him in a 0.5 gallon tank without heater at that time. I used to heat up some water when it got down to 20 degrees Celsius. I treated with Costapur (treatment for parasites) and the protuberance started to heal, with a white liquid coming out from it. He did not eat very much during that time.
Now I have moved him in an 8 gallon tank with heater and 2 protuberances appeared :(.
Can you please advise?
I am also attaching a picture.