Heat and Your Pond Fish
Have you been having high temperatures in your area? Wondering how heat affects the pond fish?
Ideal Pond Temps
The ideal range of water temperature in a pond with koi or goldfish is between 65°F and 75°F. Of course, with the pond outside, there isn’t much we can do about pond temperature. Koi and goldfish can survive winter here in Colorado (and other Zone 5 areas). In “torpor,” their metabolisms slow waaaaay down. They don’t eat and barely move until spring warms the water again.
How Could Pond Water be too hot in COLORADO?
If you are new to Colorado, you may be thinking of mountains, elk and lots of snow. Certainly true depending on where you are. Here on the Front Range, we have days (even weeks) of weather over 90°F and even over 100°F. When air temperatures rise, so do pond temperatures.
When you see whiskers like this on a fish, called barbles, you are looking at a koi!
I have yet to see the pond water warmer than 85°F. However, if it were to get that warm, we would see:
- Fish stress – While they can survive up to about 90°F, prolonged exposure is tough on them. They will slow down their eating at 85 degrees and stop all together as it nears 90. If that happens, the water temps will likely come down soon, but don’t worry about them eating. It is similar to when people don’t want to eat when they have a fever.
- Oxygen Depletion – Warm water holds less dissolved oxygen. In shallow, full-sun ponds, fish may struggle to breathe and could be seen gasping at the surface.
What you can do if pond temperatures get too high
Chances are, if you are in Colorado, the temperatures won’t stay brutally hot for long. If the water reaches 88°F:
- Stop feeding the fish.
- Make sure the pond is full. You don’t want the pond to be more shallow than it can be. The more shallow the water, the hotter it will get.
- Add shade. If your pond is shallow and always in full sun, put shade over it! Even putting up a patio umbrella where you can will help. You can put a sail cloth over the pond for shade. Did you know that fish can actually sunburn?! They can!
See those plants on the right? They’re Water Hyacinths and Water Lettuce. Their roots dangle in the water, soaking up nutrients that algae would otherwise use. Best natural filter ever! The fish will nibble on the roots which is just fine. Did you know Water Hyacinth will bloom? They will!
4. Add Water Lilies: If the pond has good coverage from water lilies that helps a lot! However, they need to be added well before the extreme heat happens. Mature, healthy lilies will produce plenty of pads to give your fish the shade and protection they need. Read more about Water Lilies.
5. Add Floating plants! Too late to add Water Lilies? Put in a bunch of Water Hyacinths or Water Lettuce! Did you know there is a Secret to getting Water Hyacinths to bloom? There is!
Extra Tips to Beat the Heat
6. Use aerators! It is important that there are aerators in the water during high heat (more so if the pond is shallow and in full sun).
7. Add 2 or 3 inches of hose water. Here in Colorado the hose water is still cold. Fish don’t like temperature changes too quickly. Be sure not to add more than a few inches at a time and use a dechlorinator.
Water Hyacinths have lovely blooms!
What about the pump in high heat?
Pumps are not usually affected by the heat. That being said, the control for the pump may be! Many people cover the pump’s control panels and electric outlets with a fake rock. While it is good to protect them from the UV rays, rain and snow, the heat can build up. Hot days and direct sun can actually cause them to over heat! If that happens, the pump may stop working.
The last thing you want during a heatwave is a pump failure! Warmer water holds less dissolved oxygen, so when it’s hot the fish need as much oxygen as possible. The pump helps oxygenate the water, which fish desperately need in the heat.
To keep your electronics from overheating you can drill holes in fake rock. Some of these already have ventilated screens built in!
Holes can be drilled in fake rock, and some rocks come with ventilated screens built in!
Kristi's Tips
A pond should have 40 to 60% of the surface area coverage of plants. It helps keep the whole environment more healthy.
Pond plants are the best experiment—you don’t even have to water them! Some will thrive, others won’t, but the right mix makes your whole system POP with beauty!
* This blog was NOT written by AI. This was written by me. I am not a professional writer, I am a pond person. Therefore, if you see a typo, please forgive me!
*No koi were harmed in the making of this content.