| I am unable to completely control them, but know that timing can be a BIG help. I try to drain the pond and dry things out to the extent possible before spawning (yeah, I know, who can predict spawning that well?). When the pond is refilled, it goes through reasonable predictable 3 week succession where there is a green water bloom, followed by a rotifer bloom, followed by a copepod/daphnia bloom. When the stars are properly aligned, the fry are ready to begin feeding just as the rotifer bloom gets going and the fry are large enough to take the larger zooplankton as those forms begin to dominate.
This schedule also does a lot to control dragon fly larvae. Most of the older dragon fly larvae are killed when the pond is drained. The dragon flies start laying eggs again as soon as the pond is filled. However, many of these eggs and/or the newly hatched dragon fly larvae become fodder for the koi fry as they grow. Some dragon fly larvae survive, but their numbers can be almost tolerable at times.
You have to experiment around to see how the plankton succession works in your region and at your temperatures. I know some guys for whom it works better to refill the pond only 10 days before the fry are stocked.
steve hopkins |