Question
QUESTION: Hello..I have a small pond with 2 koi appx 5"..and 7 gold fish appx 3-4"..Well i took them out of my pond which was 27 degrees today and put all of them in a single standard fish tank..They looked crampped up in there with the shelter houses,fake plants,ect,ect,..My question is will they be ok in there?..or should i go buy a pong heater and put them back in the pond..If it's OK to keep them in the tank they will only have to live in there appx 3 months..as here in Arizona it heats up pretty quickly..but now the nights are 27-30 degrees and that will last through Mid-March..Did i do the right thing by moving them indoors?..any advise i'll follow..thanks dave

ANSWER: How big is your pond?  How big is the aquarium?  If it's under 40 gallons or so, then it's not really large enough for them to be comfortable.  If your pond is more than about 18" deep, it should be deep enough to overwinter the fish outside in Arizona.  Where I live, we get temperatures as low as -10 degrees F but usually the low for a winter is 8 degrees F or so.  My fish stay in the ponds all winter with de-icers and aerators.  There's a ponder on my forum in Zone 2 in Canada.  She gets temperatures below 0 degrees F routinely.  Her pond is 8 feet deep and enclosed in greenhouse plastic but she's managing to keep a small hole for aeration in there.  My point is that your winter isn't that bad!  If your pond is big enough, they can stay in there.  It was stressful to bring them inside due to temperature changes as well as how much room they have.  It would be stressful at this point to put them back into the pond.  If the tank is large enough for them, I would keep them inside this winter but research how to keep them out next winter.  My page on wintering ponds is at http://www.fishpondinfo.com/winter.htm

Good luck!

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QUESTION: Thanks...but a couple of more questions..The tank is a standard tank..i think its about 15 gallons not sure tho..The pond killed/froze 4 goldfish Friday and i cherish my koi's..The pond is abotu 3 feet deep in center and 6 feet at bottom..but the koi alway take shelter onder the hugh rocks i have in there for them..i've had them for 3 years and they are so nice..I even actually saw one "yawn" today in the tank i have them in that was so cool:)..I haven't feed them for 3 weeks and they are fine..now in the tank thats normal temputares so should i start to feed them? I have all there favorites right down to cherrio's:)..I see them eating the blue gravel that i put on the bottom of the tank then spitting it back out thismake me nervous?..I wish i never took them out of the pond but 4 goldfish freezing in 3 days is not nice:( and would hate to have that happen to them..They did look like they were freaking out when they fisrt got in the tank not sure if they were in that hibernation state and i woke them up..Thanks for your help and prayers..dave

Answer
The 15 gallon tank isn't really large enough.  Can you buy a larger tank or indoor pond for the winter?  Rubbermaid stock tanks sold to water cattle are pretty cheap for 50 or 100 gallons even.  Aquarium-wise, I like the 40 gallon breeder size.

How far down did your pond freeze?  Did/do you have an aerator and/or de-icer?  The fish shouldn't have died from some ice at that large depth of pond.  They were in the shallows among the rocks and froze?  Could you provide a barrier to keep them out of the shallows in the winter?  I had one "dumb" goldfish go into the shallows of my pond during a flash freeze night (when the pond goes from almost no ice to a few inches of ice overnight in high winds and low temperatures).  Contrary to what a few have told me, when fish freeze, they die.  When my poor goldfish thawed, he was 100% dead.  It must have been hard to find 4 goldfish frozen in.  Did you get them out or are they frozen in still?

Your pond is deep but how many gallons is it?  Did the fish overwinter fine the previous two winters?  I'm surprised they aren't larger fish after three years.

Once the water temperature is up to room temperature, wait about three days before starting to feed again.  Cheerios are a good starter food.  Goldfish and koi will both pick up gravel and mouth it and spit it out.  That's totally normal.  They're searching for food and are also curious.

Goldfish and koi don't truly hibernate.  They just slow down.  It's shocking if they are warmed up too quickly. Plus, being in a new place in new water is shocking.  Hopefully, they will overcome that.