Caring for Pond Fish in Spring

For us, Spring brings the excitement of warm weather and the end of the winter blues. But for our fish, Spring can be one of the hardest times of year. It’s the most vulnerable time for fish, so knowing the best way to care for them is extremely important.   

Why is springtime hard for fish? 

There are actually a few reasons the spring season is difficult for pond fish. Like humans, a fish’s immune system is suppressed by abrupt temperature fluctuations. So, when water temperatures fluctuate, harmful bacteria present in the pond attack the weakened fish. Their immune systems can shut down, especially during danger zone 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. They will also deal with hungry predators looking for their first meal after a long winter. Whew...that’s a lot to deal with in one season!  

Good water quality = happy fish 

Good water quality — not to be confused with water clarity — eliminates most of the potential concerns for your fishes’ well-being. Do a little spring cleaning — it’s not just for inside their home, it applies to your landscape and water features too. 

  • Clear away leaves and debris from in and around your pond.  
  • A partial water change is recommended to keep your fish healthy but make sure to take the fish out and put them in a tank/container with pumped out pond 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, turn on your filter so it can recycle the good bacteria. This process can take up to a few weeks after being inactive in winter. Readd your pond fish gradually, ask your fish dealer for additional advice. 
  • When cleaning your pond, avoid scrubbing away the slime coat (beneficial bacteria) and velvety algae that coat the liner. They contribute to the reduction of nitrogen and other fish waste in the pond.  
  • Reduce organic buildup and keep sludge to a minimum by using Sludge Remover. Use Water Clarifier 48 hours (about 2 days) prior for even better results.  
  • Test your pond water and speak with your pond fish dealer about the results. Test for ammonia, nitrites, pH, and alkalinity to see if the filter can handle the waste load of your pond fish. The results will determine how much food to feed your fish.  
  • In the end, one of the most important things to do is supply your aquatic life with ample oxygen. Add aquatic plants, aerators, fountain nozzles, and/or spitters to introduce oxygen into the water to help the water quality and increase your fishes’ lifespan. 

Feeding pond fish in spring  

Feeding your fish in spring is important for rebuilding their energy and supporting 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 once the water temperature stays consistently above 50°F. However, a good rule to keep in mind is: If your fish 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. (Note: do not confuse seeking food with coming up for air.) Due to their low metabolic rate in the winter, food is not easily digested, so give them something easy on their system like a wheat germ-based food. Once the temperature reaches about 60°F, you can switch to a higher protein-based diet. Be sure to get in contact with your pond fish dealer for more advice. 

Continue to observe your fish in your pond regularly. 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 these symptoms could indicate that the combination of winter’s stress —possible harmful bacteria or parasites and little food — is affecting your fish. Be sure to isolate them and after a quarantine period in a separate tank, these fish can usually be reintroduced to the pond.  

With these guidelines and the expertise of your fish dealer (see condensed list of questions below), you can provide the best care for your pond fish this spring. 

5 Questions to ask your pond fish dealer in Spring

  • I tested my pond water, and these are the results: ___. Is it balanced? If not, what do you recommend? 
  • What type of food should I be feeding my pond fish? Make sure to mention the current water temperature.  
  • How much food should I be feeding my pond fish? You’ll want to know the quantity and recommended frequency. 
  • How frequently should I perform a water change, so my pond fish (insert species) have the best spring season? 
  • My pond fish are experiencing these symptoms: ___. What can I do to help my fish?