Pond fish health:
We received a call that went like this, “Lost my fish. I tested the pond water and ammonia and phosphates were high. What do I do?” Similar calls include, “My fish died this spring after being fine all winter”.
Often, people blame fish death on temperature swings. We are not vets, and we have seen fish die from temperature swings. Against our suggestion, a customer purchased fish from a 70 degree store, transported them in a 75 degree car, and 15 minutes after arrival put them in a 45 degree pond. That was temperature shock and the fish died.
Experience shows us gradual temperature change does not hurt fish. When our techs are cleaning ponds, the water is changed completely in a few hours. By slowly changing water temperatures over a longer period of time, the fish have never died in our process. This leads us to believe the problem is a water quality issue.
When your summer filtration is shut down, your pond may have higher than normal levels of ammonia, nitrites, and phosphates. This occurs in spring and again in autumn for Minesota ponds. (The time frame may be different if you don't live in Minnesota.) Ammonia and nitrites are toxic to fish.
Where do the toxic ammonia and nitrites come from?
Fish excrete ammonia as their waste. Nitrites and phosphates are released as dead plant matter starts decomposing and breaking down into minerals. Beneficial bacterias convert ammonia waste into nitrites as well. So your pond will have nitrites and ammonia coming in but the plants in your bog, regular pond plants, and good bacteria which remove the toxins are not actively growing if the water temperature is lower than 50F. This creates a toxic environment for pond fish.
How we maintain a healthy fish pond:
The easiest way we’ve found to prevent fish death is by adding Cold Water Bacteria regularly. This can be done manually with the product pump bottle. Add bacteria every week until the water warms up past 50 degrees F. When the water gets over 50 degrees consistently switch to regular pond beneficial bacteria to keep your water clean and clear.
About cold water bacteria:
When the water is cool, like our Minnesota pond water is after the spring thaw, beneficial bacteria are less active. Because the pond is a closed system just like an aquarium, you will need to add special “cold water bacteria”.
The cold water bacteria are active at low temperatures and convert unwanted ammonia and nitrite into harmless nitrates. With toxic compounds converted to harmless ones, your fish will stay healthy and strong.
Some cold water bacteria mixes like the Aquascape Cold Water Bacteria also contain marigold and vitamin B which help bring out the natural colors of your fish!
Cold Water Beneficial bacteria is completely safe for fish, pets, plants, and wildlife. By using it you can keep your pond healthy and clear and safe for your fish. Click here for more information or to order cold water bacteria.
By Becky Chudek- horticulturist, mom, wife, follower of Jesus
Jeff Chudek has been building ponds and waterfalls professionally since 2005. As a kid, his favorite time of year was spring, because the spring thaw created so much mud and puddles, and all the trees and plants were waking up. He loves figuring out the best way to use something, and fixing things that are broken. He's good at coming up with ideas, and helping choose the best idea for you.