Fish super-stressed; temp flux to blame?
Hi all, sorry to be such a foul-weather friend to the forum. We awoke this morning to a dead 20-inch koi. All the fish have been acting stressed this winter, hanging near the surface even when air temps were in the 20s, standing separately here and there instead of in a group like usual, and through the pea soup I can see clamped fins and pink tinge on them.
The weather has been bizarre, like everywhere else. A week of teens and 20s, then a couple days of 60s-70s, up and down like that. Record 65 at 3 a.m. today when the torrential rains rolled through, 55 now.
I did see something a few weeks ago I've not seen before in the 10 years of this pond, occasional thick green bubbles floating to the surface. And today, after the aeration, there's a whitish scum on the pond surface. It doesn't smell like soap or anything and I don't have cause to suspect vandalism.
We did vacuum in the fall, which is unusual; we usually vacuum in the spring only. Before the water clouded we noticed one of the huge 10-year-old koi (The Original Kittyfish, Andrea :) ) seemed like she might be getting pop-eye.
The dead fish this morning had clear gills, not too pink, maybe a couple of black spots on him I assume were parasites, but overall he looked great.
A water test this morning showed >8.8 pH, but the test solution might be faulty. A second test with another kit showed about 8 pH.
Ammonia 0.2 or so.
The pond is a 12,000-gallon pool, lined, no rocks, filters are off for the winter like always, no other variables from past years except the fish are bigger. We have about 20 koi over 15 inches, probably another 15 or so between 10 and 15 inches, and I'm guessing about 20 8-inch goldfish. From March to October the pump pulls from an additional 1,200-gallon settling pond, pushes through three 150-gallon stock tank filters and returns through three falls each 4 feet high.
This morning we hooked up the skimmer filter and hung the pump near the surface, shooting a dozen streams of water about 5 feet through the air to aerate in case there's a lack of oxygen stressing the fish. The fish have not gathered over there near the falls, so maybe that's not the problem. At this point I'm just looking for the can't hurt, might help actions.
I hesitate to do much else to change things out there, since the temps are going to plummet again tonight and the last thing those poor fellas need is big giant changes in their environment. So I guess I'm writing in case someone else is in the same boat and found a helpful hint.
Thanks, and I hope everyone's ponds are healthy and happy.