Spring May Have Sprung, but We’re Not Free of Winter Just Yet…

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hungry koi fish

March came in like a lion this year – when it wasn’t snowing it was blowing, cold and hard. Things are finally starting to warm up, with temps above freezing here in Long Island, giving some hope for the month going out like a lamb. But Winter hasn’t let go its grip just yet. As the crocuses bloom and the buds start to swell, the thermometer in my pond tells a cold, cruel tale. The water is still closer to freezing than the minimum temperature my fish need to be able to digest their food.

Mind you, they are doing their best to convince me otherwise. They come over when I approach the feeding rock, hopefully blowing bubbles at the surface just in case I’ve thrown any food in. The Koi are hungry, and they should be. They haven’t eaten since before Thanksgiving. All they’ve lived on for the last four months is the fat they stored up for winter. They don’t look so fat now. They are at the last of their reserves. So, why not feed them? Not much, “joost a taste”, like Grandma use to say? 

Well, that kindness, done for all the right reasons, would quite possibly kill them. Fish are cold-blooded; their internal temperature matches that of the surrounding water. Their digestive processes involve the activity of bacteria, just as ours do, that help break down the food they eat into compounds that are readily absorbed by the gut. Those bacteria are sensitive to temperature; they slow waaaay down when temps are low. The food ferments and decomposes before it can be digested, and the byproducts of decomposition can be lethal. Ever had food poisoning? Excruciating pain, cramps, fever and worse? Well, that’s what happens when food rots inside you, or your koi. These last few weeks make me nervous. This is the time of year that I’ve lost fish in the past, once when a fish attacked by osprey couldn’t fight off an ensuing infection, once when a late snowfall-and-road-salt event washed salt into the pond as the piles on the nearby road melted, and once when well-wishers sneaked food into the pond. (Oh, they were sooo HUNGRY, the poor things.) Not anymore.

The beneficial bacteria that aid in digestion slowly come up to speed as temps warm. It’s generally accepted that over 55 degrees the chance of a fatality due to feeding drops to near zero. That said, please help your fishes’ awakening systems by feeding fish an easily digestible food based mainly on carbohydrates, usually labelled Spring-and-Fall mix. Bear in mind that their immune systems are at the lowest level all year; maybe a stressful cleanout can wait for a few weeks? A fish that bruises itself or loses scales when she is startled and slams into a wall is at higher risk now than at any other time. Resist the temptation, no matter how much they beg; Spring is right around the corner. 

Read more about spring and your pond in our blog: Spring Is For Sprucing!

About the Author:


Demi has been in water garden construction since 1986. As Atlantic’s Director of Product Information, if he’s not building water features, he’s writing or talking about them. If you have a design or construction question, he’s the one to ask.

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