seasonal koi care

Remember, caring for your pond is a year round proposition. Even during Winter months you need to check that your deicer and bubbler are working properly and that there are no casualties. It may sound obvious, but your koi can only die once. There are no second chances and the "should haves" don't count once a fish is gone

It's a real tragedy when mishaps could have been averted with a bit of reading, some planning and a little diligence
You can only maintain a happy healthy koi collection with year round care

your pond in Spring Time

Spring is an exciting time as we look forward to warmer weather and a lot of activity in our ponds. Check to make sure all of your fish survived the long cold spell and remove any casualities immediately. If there are any missing fish, they may be decaying on the bottom of the pond or taken by a mink
  • Carefully remove any ice from the pond as soon as possible without smashing it [the pond then warms faster]
  • Perform a large water change - up to 40% if possible [use water conditoner]
  • Test the water quality [Ammonia, Nitrite, pH, KH]
  • An aerator should be running
  • Remove any leaves and debris you missed
  • Add some salt, 2-3 lbs. per gallon is recommended
  • Turn your filters on and start feeding [wheat germ based foods] when the water reaches 10 Celsius
  • Do not introduce any new fish and carefully observe your fish for signs of distress
  • Watch for fish spawning in late Spring


Summer pond care

Summer is the peak activity and growth period for your fish. Koi are most active in warmer water and should be fed several small meals a day. Continue to monitor your ponds water quality and this is the best time to add fish to your collection [quarantining is recommended]. It is critical to maintain WQ [water quality] as the fish will produce more waste and require more oxygen in warmer water. Don't forget, warmer water holds less oxygen so aeration is the order of the day. Many people lose fish because they run their ponds with just a single pump. When that pump inevitably fails, overstocked ponds can run out of O2 very quickly
  • Your filter may not be cycled by early Summer so continue water testing
  • Feed several small meals per day - all food should be eaten within 5 mins.
  • Add new fish and plants with caution so as not to innoculate your pond with pathogens
  • Adequate aeration and backup systems should be in place
  • Regular 15% water changes at least 1x per month, be careful not to chill the fish with the hose,
    use water conditioner and a volume timer to avoid overfilling
  • Properly sized filters usually require maintenance 1x per month, always clean with pond water only

  • Spring is a critical time as fish are weakened from the long Winter
  • Summer officially starts for fish when the pond temperature reaches 19 Celsius
  • A net can make the pond closing a whole lot easier
  • In really cold climbs a Winter cover is highly recommended


Autunm Pond Advice

Fall is an important time for your fish. You need to prepare them for Winter by continuing to feed heavily. It is vital to do a large water change and ensure the pond is clean for Winter. Installing a greenhouse in early October prevents any leaves from getting into the pond and extends the growing season

Adding some salt for Winter is a good idea, and 0.1% - 0.2% is acceptable rate [1 lb. - 2lbs. per 100 gallons]. I have read recently that adding salt for the Winter is not a good idea because it lowers the freezing point. The fact is a 0.30% level will merely lower the freezing point a fraction of a degree - not a cause for concern

Remember, fish need to be in good condition to survive the Winter. If any of your fish were recently sick or are in poor condition at the time of the pond closing then you should Winter them indoors. The key factor is to realize that the fish will be going 5 months with little or no food. Logic dictates they need to be healthy. of a sizeable mass and properly conditioned during the Summer to ensure a good chance of survival
  • Switch from high protein to wheat germ based foods when the water is 16-17 Celsius
  • Continue to feed as much as the fish will eat for as long as they will eat [remove uneaten food]
  • A net or Greenhouse covering installed in early October is of huge benefit
  • Weak and young fish should be Wintered indoors
  • Add salt to raise the salinity betwee 0.15% - 0.20%
  • A large water change as late as possible in the season is recommended
  • Mininumly a deicer and bubbler should be installed

Winter Concerns for your Pond

A long cold Winter is hard on Koi and we see the cumulative effects of this manifesting in the late Winter with fish casualties. Ammonia levels may climb druing the Winter as nitrfiers are not active. However don't worry as there can be 2.5x the amount of ammonia present when comparing the toxic effects between cold and warm water

If you do not cover you pond, you minimally need to run a deicer and a bubbler over the Winter and check that they continue to opeate. They maintain a hole in the ice to allow gas exchange - rotting leaves create toxic hydrogen sulfide. Large fish need a lot of O2 and can go belly up quickly, consider 2 aerators on differant circuits. Do not run a large volume of air [air compressor] from the bottom of the pond that turns over the water. This can "super chill / cool" the water which can kill your fish. If your pond does freeze over, do not smash the ice ! Bowl a kettle to melt through it or use a propane torch

Waterfalls should not be run in the Winter. Besides the aforementioned potential of super chillingA process where a liquid or gas is lowered to a temperature below its normal freezing point ice dams can form and divert water out of the pond possibly draining it dry [dependant on your plumbing setup]
  • Always use both a deicer and bubbler and make sure they are always operational. Small fish may survive without a bubbler, but bigger fish [8"+] will not
  • Never smash the ice as it can shock the fish, melt ice with a boiling kettle / torch
  • Do not run waterpumps, skimmers, waterfalls. They super chill and ice dams can drain water out of the pond
  • Check for any dead fish and remove ASAP
  • Read more on our Koi Winter Survival Page
  • Also look at our Predators Page - mink can clean out your pond during Winter