u/PossibleOk4660

I have 5 golden tench that have all been a little rough since the start of spring due to no maintenance from the last pond owner. I've been trying to help these guys but don't have a microscope to check exactly what it is and the pond is quite large so it's hard to net them.

Does anyone have any idea why it might be looking this pale with blotches? I treated the pond as I also have some koi and they seemed much more active after FMG and they are now currently on acriflavine and seem fine but I was wondering if I should wait longer for the marks to clear or should I retreat with something else?

One tench was sitting on the bottom constantly and would occasionally come up to feed but then go straight to his same spot on the bottom of the pond. But yea since treatment they have improved much but I'm wondering if I should dose a second time if what they have is severe enough for a second dose or if I should continue to wait for the current acriflavine to keep working as it's only day 3 on this treatment