Koi Jumping at Filter?

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Umbra2002

Aquarium Advice Newbie
Joined
Jan 1, 2022
Messages
4
Hey, all!

I’ve 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. I’m back now under this new account (unfortunately don’t 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 that’s 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 I’m looking at getting under control (the pond gets direct sunlight for now, and we’re 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, they’ve remained in the 60s for a few days now. I’ve been feeding small amounts again, but maybe I’m 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 “waterfall”?
 
Hungry, playing or catching bugs could all be possible, watching them longer / closer to see what you have going on. I have only had a 125G + 50G filter and kept a heater in there to keep water less than freezing hard, but definitely be careful about feeding them in winter. Make sure it will be warm for a few days or more and then stop a couple / few days before the cold comes back. It could be tricky. I am not too familiar with Kentucky weather. And fall time food.

Any fry in the pond? Also maybe the water is a little warmer there???

Share pics!

How exciting
 
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