Sailfin with LARGE white spot.....help!

[Jc1975]

Hi. My sailfin who I have had for over a year has this large white spot appear the other day. I can still see the yellow dots but it seems to have grown. I noticed it yesterday. Can anyone tell me what this is and how to treat???

Thank you!

 

[vetteguy53081]

Looks bacterial.
Lets start with water quality. What test kit(s) are you using and what is your:
Ammonia
nitrate
salinity
ph
Temperature

Are you using RODI water or tap water from the faucet ?

Treatment- maracyn 2

 

[Jc1975]

Looks bacterial.
Lets start with water quality. What test kit(s) are you using and what is your:
Ammonia
nitrate
salinity
ph
Temperature

Are you using RODI water or tap water from the faucet ?

Treatment- maracyn 2

Hi. My nitrates were high all other tests are good.. We just did a water change. Salinity is 1.025 and we use our own rodi water. Thank you for the advice.