The Best Care for Your Koi or Fish in Spring

Spring brings the excitement of warm weather and the end of the winter blues.  But for your fish, spring can be one of the worst times of year.  This is the most vulnerable time for fish, so knowing the best way to care for your fish or Koi is extremely important.

Spring is rough for fish because they are cold-blooded creatures that cannot produce their own heat.   Fish produce isoenzymes to provide them with bodily functions such as the production of energy, regardless of temperature.  As the water gradually warms up in the spring, these isoenzymes are no longer produced and regular enzyme systems begin to function.  However, during spring the water temperatures experience ups and downs, which make it hard for fish to survive.  Their immune systems shut down, especially during the Aeromonas Alley or the danger zone of temperatures between 40°F - 50°F, making it hard to fight off harmful bacteria that thrive in the cold water.  Parasites are also active and may have attacked your fish or Koi during the dormant winter months.  This is when the fish are most likely to develop illnesses.  Then they also have to deal with a large amount of hungry predators looking for some food after a long winter.  That’s a lot to deal with in one season!

Caring for your fish means caring for your pond.  Clean, clear, and high quality water is important for your fish’s well-being so make sure to restore and clean your pond.  Clearing away any leaves and debris that have made their way into your pond over the cold winter is the first step and will keep the waste load at a minimum.  Make sure to clean the pond while not scrubbing away the beneficial bacteria and velvety algae that coats the liner as they contribute to the reduction of nitrogen and other fish wastes in the pond.  You want to keep the sludge at a minimum by using Sludge Remover to promote balanced water chemistry.  A partial water change is recommended to keep your fish healthy but make sure to take the fish out and put them in a container with pumped out water so the shock of new water does not affect them.  While in the tank you can use pond salt to fight parasites.  Using a microscope and observing the fish for parasites or illness is important to stop any spread of disease before returning to the pond.  Once the partial water change is complete, put the fish back in the pond and turn on your filter so it can rebuild good bacteria, which can take a few weeks after being inactive in winter.  Then test the water for ammonia, nitrites, pH, and alkalinity to determine if the filter is able to handle the waste load of the Koi. This will determine how much food to feed the Koi or fish.  Plants and aerators will introduce oxygen into the water to help the water quality and increase your fish or Koi’s lifespan. 

The best thing to do is to supply your aquatic life with ample Oxygen and make sure they experience as little stress as possible.  Feeding Koi or fish in the springtime is important in rebuilding their energy to support their immune systems.  Feeding them the right diet at the right rate will increase their chance of survival and optimal health.  You should start feeding your fish sparingly when the water temperature is consistently above 50°F.  However, a good rule is: If your Koi are looking for food at the surface of the water, they’re probably hungry and have decided for themselves that it is time to start eating.  Due to a low metabolic rate in the winter, food is not easily digested so give them something easy like any wheat germ based food.  Once the temperature reaches about 59°F you can switch to a higher protein based summer food.  Continue to observe your fish in your pond on a regular basis.  Check for clamped fins, redness in the skin or fins, swollen eyes or lips, or fraying, rotting fins, and white slimy patches.  Notice if any fish keep to themselves, away from their school.  All of these symptoms could indicate that the combination of winter’s stress- possible bacteria or parasites and no food- is affecting your fish or Koi.  Once your fish are deemed to be in good health you can add new fish after a quarantine period in an isolated tank. 

Follow these guidelines and you will keep your fish and Koi happy and healthy!