Red spots and areas on fish

[Fino]

Hello,

Unfortunately my fish has been developing red spots and areas on his body. Would anyone possibly know what disease this is and how I can treat it? He appears to be acting normal so I can't work out whether this is causing him extensive damage or not.

Many thanks,

Julian

Edited November 10, 2021 by Fino
Removing an unneeded paragraph

[Arctic Mama]

Hi there! We need this form filled out as completely as possible, as well as someone up pictures of the animal under bright light, in your hand or from the side in the tank is fine.

DIAGNOSTIC CHECKLIST

Test Results for the Following:

* Ammonia Level(Tank)

* Nitrite Level(Tank)

* Nitrate level(Tank)

* Ammonia Level(Tap)

* Nitrite Level(Tap)

* Nitrate level(Tap)

* Ph Level, Tank (If possible, KH, GH and chloramines) 

* Ph Level, Tap (If possible, KH, GH and chloramines)

Other Required Info:

* Brand of test-kit used and whether strips or drops?

* Water temperature?

* Tank size (how many gals.) and how long has it been running?

* What is the name and "size of the filter"(s)?

* How often do you change the water and how much?

* How many days ago was the last water change and how much did you change?

* How many fish in the tank and their size?

* What kind of water additives or conditioners?

* What do you feed your fish and how often?

* Any new fish added to the tank?

* Any medications added to the tank?

* List entire medication/treatment history for fish and tank.Please include salt, Prazi, PP, etc and the approximate time and duration of treatment.

* Any unusual findings on the fish such as "grains of salt," bloody streaks, frayed fins or fungus?

* Any unusual behavior like staying at the bottom, not eating, etc.?