I’ve been told it’s bad luck to name your koi – ooops, I’ve named them all and will continue to do so. Maybe we shouldn’t tempt fate by congratulating ourselves as we did just before the new year. Pond digger and I were thinking that by this time last year we had lost a few koi. Last year we ended up losing a lot of koi to illness and probable electric shocks from a faulty heater we had in the pool.
This year, everything is looking good and then a larger shiro that we had started acting funny. Of course, this koi, named Super by his previous owner, has always been a little wacky but now he was crazier than usual. We would see little bouts of erratic, frenzied swimming (almost like a mini seizure) and he spent a lot of time at the surface. Not gasping but definitely looking as if he needed more air. This started out on January 1. On January 2, we find Butch Cassidy, a nondescript shiro on his side. Butch had not shown any symptoms earlier and the only odd thing I found was a red spot near his mouth. Gills looked good, no unusual swelling…the pond digger said his body looked like he had the zika virus since his head was so small compared to his body. The next day, Super is found in the morning on his side as well. We set up a quarantine tank, popped him in and headed off to work. Unfortunately dead as a doornail when we return. Once again, gills are fine, had some redness due to stress(?) and a small spot of red on his head. Two koi in two days and on January 4, Black Jack is on his side, barely alive. We consulted with some koi club members and Matt Sklar recommended we set up a carbon filter. We did this last year when we had our issues and the koi perked up immediately. This year we didn’t see any dramatic perking up but there have been no deaths since the carbon filter has gone in. Maybe the pool exudes something that messes with the koi? I did try to play doctor with Black Jack and injected him with some amikacin, no luck. We considered giving the rest of the koi prophylactic shots but none of them have exhibited any odd behavior. So it’s a mystery illness.

If we had been a little more clever, we should have put in a carbon filter from day one of indoor koi land. Our water doesn’t show any metals through testing. Water temps hover around 50 – 52 degrees, the koi are not eating, the water parameters are great. Our friend told us that some water conditioners contain an ingredient that is actually harmful to koi. He thought we could try using sodium thiosulfate instead of the water conditioner. Sodium thiosulfate can be a little pricey and require some lead time to order, but the pond digger is a chemical manufacturing CEO, so there’s a few scoops of this stuff laying around the plant 🙂 We never did try out the sodium thiosulfate and opted to use 10 pounds of carbon sourced through Bulk Reef Supply.


Outdoors, it’s been pretty cold and the holes kept open by the aerators in the upper pond have frozen over. One of the holes froze completely and the remaining open hole began to form a little spitting volcano. When the pond digger went out to open up the frozen hole he could tell there was a lot of air trapped under pressure under the ice. Who knows what would happen if we let the aerators continue with no escape hole for the air??? We won’t tempt fate trying that scenario out. I don’t think my volcano will be growing any more for awhile.

70 more days until the first day of Spring. Of course the first day of spring usually means we can only think about getting our koi to the outdoor ponds in about two months. I’m hoping my koi stay healthy and I do not lose anymore this winter, crossing my fingers.
Indoor koi land today (watch in HD1080):
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