| Hi Renee, so the pictures are not too clear. But I think we may be looking at a mis-diagnosis. the 'spots' look too large. Maybe carp pox? Can't tell.
Also IF you do indeed have ich , moving fish to a new 20 gallon tank to treat ( and I assume then return to the 55 gallon tank) is only introducing them to the parsites left behind in the old tank. Unless you keep them out of the 55 for a considerable time. And if you do that, you are keeping 18inches of koi in 20 gallons of water - this would lead to serious ammonia problems and bacteria problems. Looks like the proverbial 'rock and a hard spot' ! JR |