We have a 1,500 gallon koi pond with koi and goldfish. The goldfish all look fine, the comets and the fancies, but the koi have bloody red streaks and patches in their fins. Some of them are rather tattered. Several of them developed excess slime coat on their fins, now some of them have white patches, almost like very large grains or small nodes. It is not ich, it is much larger. In addition, about 3 of the koi developed grayish grows on their heads or faces. The ones who did the worst, we brought inside and quarantine them in stable temps with 80% water changes every other day, and they healed right up. I know this sounds like “water parameter issue”. Just checked with an api liquid test kit, no ammonia, no nitrites, the nitrates are barely registering.
I am totally stumped. I am guessing it is something to do with the inconsistent spring temps? The temps dropped from 70F to 20F overnight last week. 50 degrees in less than 10 hours. We lost 6 koi in the cold snap, I’m guessing it was extra hard on them because of the very recent stress from my uncle’s koi?
But anyway, thoughts?
I am totally stumped. I am guessing it is something to do with the inconsistent spring temps? The temps dropped from 70F to 20F overnight last week. 50 degrees in less than 10 hours. We lost 6 koi in the cold snap, I’m guessing it was extra hard on them because of the very recent stress from my uncle’s koi?
But anyway, thoughts?