Koi Jumping at Filter?
Iíve been keeping fish for most of my life now, and this forum was always excellent at teaching a young me the ropes of fish-keeping. Iím back now under this new account (unfortunately donít have access to anything attached to my old one) to ask about my latest dive into this world: ponds.
Over the summer and into the fall, my dad and I worked hard constructing a pond thatís roughly 3500 gallons, perhaps a bit more. It was certainly a learning experience, and though some of my tank-raising knowledge applied, there was a lot of new things to research. It was a lot of fun. Around mid-October or early-November, the pond was cycled, and we got four koi and some rosy red minnows. In mid-November, with everyone growing steadily, we added some mosquitofish, and just recently, an albino sterlet sturgeon (my dream fish for a pond).
The hardy water lilies were growing well through October, and I brought the water hyacinth in for the winter in November. The rosy reds have grown much bigger, and I stopped feeding the koi when the weather grew really cold (in the 20s in Fahrenheit or below). We live in Kentucky, for reference-sake.
Things seemed great up until tonight, when I noticed one of the smaller koi swimming along the edge, where the outflow for the filter is. It was jumping at the water flowing down, and swimming up it for brief periods of time before swimming back down. The water has a bit of algae in it that Iím looking at getting under control (the pond gets direct sunlight for now, and weíre constructing shade for it), so I was afraid the oxygen levels might be too low. But the sturgeon is still very active and eating consistently, and I was under the impression that it was much more susceptible to low oxygen than koi.
My other hypothesis is that it might be hungry. Kentucky has received a very warm winter this year, and although temperatures were in the teens earlier this winter, theyíve remained in the 60s for a few days now. Iíve been feeding small amounts again, but maybe Iím not feeding enough. Spiders sometimes build on the sides of the outflow of my filter, and small insects are always flying around it.
Could it have been trying to catch something to eat? Or maybe even just playing in the ďwaterfallĒ?