Backyard Aquaponics
A place to discuss aquaponics

If you have white spot my advice is get them in the freezer
I had a outbreak in one system and tried to treat them ended up losing most and just killed the rest in despair
Lost 80 big fillets
The more you try to treat them the more stressed they get and it spirals out of control

Symptoms
White spots like grains of salt on head
Normally the fish would huddle in a tight school when I looked in the tank
Once infected they cruised around sort of half blind and wouldn't feed

I took all the fish out Nuked system with chlorine , drained system and I am leaving it empty until spring
Apparently in cold water it can survive for 6 weeks or more without a host (fish)

I have another system 2 steps away that has no sign of disease it has me stumped where it came from.
I havnt lost fish to disease before

Read about the life cycle in cold water they multiply rapidly
Best way to knock it off is to run your water pretty hot for 4 plus days , not really practical this time of year and in your big pool more or less impossible.

If you have Saprolegnia as well you have your hands full
My mate lost a heap of fish to that one last yr when the water got real cold after a run of minus temps overnight.
I would certainly try more salt