Explanation for Fish kill in Pond?

[KenW]

All of the blue gills (sunnies) in one of my ponds are dead and floating. Cleaned them up and saw no obvious causes of death. The bass, frogs, other creatures are all fine and seem quite content. Just the bluegills died. The Pond is located in the northern Catskills of New York is about 100 feet long, 30 feet wide 6 or 7 feet deep in the middle. the fish look to have been dead for a week or so. the only thing I have done out of the usual was soaked some bare root apple trees in the pond overnight before planting a few weeks ago, but cant see how that would have an impact. Any ideas???

[zootycoonmaster2006]

The roots might have had soil in them and might have gotten into the blue gill's gills. They got all the soil before it harmed the other fish. Try not to soak anything with dirt on it in the pond.

~ZTM

[magicman116]

I can't see anything connected to the apple trees causing the fish kill. Since it was all one species of fish, there is the possibility that you are dealing with a host specific parasite or disease, but without any external signs or performing a necropsy in the dead fish it would be impossible to say for sure.

I wouldn't suspect chemical agents at work as they wouldn't be so selective and would in most cases affect the frogs first in any event.

I have not been following the weather for that area and don't know how temperatures have been, so check out the link below to see if either summer kill or winter kill could apply. Both of these usually affect larger fish first, but can be limited to shoreline fish such as blue gill.

Without any other information I would assume a parasite or disease that is host specific and only the bluegill would be affected.

MM

http://ohioline.osu.edu/a-fact/0008.html