I currently have two young koi fish, and they need a bigger pond. My dad and I are planning on making one in our backyard, but it gets incredibly hot in the summer. Is this dangerous to the koi, and is there a way to avoid it?

  • 2
    How warm does it get in numbers?
    – SerenaT
    Commented Jan 21, 2021 at 9:57
  • It's usually in the upper 90s and we do have 100+ F days. The summers where I live are VERY hot and the winters are incredibly cold. Commented Jan 29, 2021 at 0:00

2 Answers 2


It will mainly depend on pond exposure to the sun, it's location and construction, meaning that if you don't have enough water, enough shade and a good ratio fishes-water volume you will need to be extra careful when the sun hits.

A good spot for your pond is where it takes sun only during morning. It will give enough light to your plants (4-6hs) and keep temp cool.

Although if there is no way you can skip direct sun you will need to be aware of water temp but most important your koys behavior to react and cool the temp by changing some amount of water (10 % fresh water and don't forget to dechlorinate).

Good luck with your new pond!


My Koi pond is 80+ F most of the summer and probably reaches 90 F max. I have good aeration and no direct sun . The 2 koi don't seem to mind; they are about 24" and 30" long.

  • Kois can take a wide range of temperature but like most fish they don't handle shock temperature well and that's what we want to avoid as well as not too high temp so there is no good oxigen for them. Commented Jan 21, 2021 at 21:06

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