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How to Add Fish to Your Pond

How to Add Fish to Your Pond

Fish are low-maintenance pets that add energy and life to your pond. It's soothing to watch them swim and explore. These aquatic pets become social, surfacing for feeding time and snacks to say hi. Whether you're a seasoned pond owner looking to add a new addition to the family or just built a brand new pond and looking to add some pond life for the first time, here are some tips for adding fish to your pond. 

Is Your Pond Ready?


Make sure you have enough room in your pond for the full-sized adults your fish will grow into. As a rule of thumb, make sure you have 10 gallons of water for every inch of fish. Calculate these requirements based on the estimated full size of the fish. The old saying "a goldfish will only grow to the size of its bowl" is a myth. These fish need room and, if kept in too small of an environment, can have health issues and even shorter lifespans. 

Overcrowding (adding too many fish to your pond) can be a serious issue that can lead to poor water quality, fish sickness, and even death. Fish produce waste, and if the pond's bacteria cannot break the waste down in time, it can lead to unhealthy water conditions in the water. 


Pond depth is important for winter and summer. If your pond is too shallow and located in direct sunlight, the water can quickly heat up to an unhealthy temperature. When water is too warm, it can't hold as much oxygen, which is important for fish. Quick changes in temperature can also shock a fish's system. 

Many non-tropical fish can overwinter in the pond if it is deep enough. A good rule of thumb is that your pond should be at least 24" at its deepest point and 36" or more for locations that anticipate harsh winters. During the winter, the deepest unfrozen section of the pond becomes the warmest, and that is where the fish will stay until spring. You can alternatively move the fish into an indoor tank for the duration of winter.

Filtration and Aeration

Does your pond have a filtration and aeration system set up? Filtration is important for water quality and for preventing algae growth. There are three main types of filtration, mechanical, biological, and UV clarifiers. The mechanical filters remove smaller debris by passing the water through a filter pad. Biological filters use good bacteria to break down fish waste and nutrients in the water. UV clarifiers break down algae and other bacteria at the microscopic level using ultraviolet (UV) light. Aeration is extremely important for keeping the water oxygenated year-round and preventing algae growth. 

Water Quality

If your pond water is clear, then it's healthy, right? Unfortunately, water clarity is not the same as water quality. Crystal-clear water could have high levels of contaminants that can be deadly for fish. Before you add any fish to your pond, perform a water quality test

What are you testing for? Check the levels of pH, dissolved oxygen, ammonia, nitrites and nitrates, chlorine, water hardness, and phosphates. 

Tip: You can also take a sample of your pond water to an aquarium supply store, and they can perform a water test (often for free).

Brand New Pond

If you've just installed your pond once you've added the filtration system and aerator, you need to wait until your pond has cultivated enough good bacteria before adding your fish. The good bacteria will help break down the extra nutrients from the fish waste. 

Adding beneficial bacteria, helps to give your pond a kick start and boost the good bacteria. If you've filled your pond with tap water, make sure you also use our Chlorine Remover plus Conditioner and follow the instructions, waiting 24 hours before adding your fish. 


Plants are important for the pond's ecosystem and the fish. Some pond plants have different roles in the pond. Marginal plants help filter out nitrogen in the water, while floating plants provide shade and help protect fish from predators. 


Some variety of goldfish grows up to 15 inches long, while koi can be two or three feet long. A healthy koi can live over 30 years, and some goldfish live 12 to 15 years. While fish make great pets, make sure you're ready for the commitment before heading to the pet store.

If you move or need to shut down your pond, they will need to be re-homed. They can not be "set free" into a local stream or freshwater river. In the wild, these fish are invasive and not native to the area. They can upset the local ecosystem and overpopulate. 

What Fish to Choose?

The common goldfish are hardy, making them a good choice for a first-time fish. Some fancy goldfish aren't the best swimmers and are more delicate and vulnerable, like the bubble-eye and lion head. When kept with regular goldfish or koi, they can get bullied or compete for food (usually losing because they are slower). Some fish, like mosquito fish will eat any mosquito larvae in the water. You can also add other pond critters like freshwater shrimp, crabs, lobsters, and snails. 

Where to Buy Fish for a Pond?

Goldfish, koi, and other pond fish can be found at a local pet store or aquarium. Some special varieties of goldfish and koi will need to be purchased from a specialty breeder. Always purchase your new fish from a reputable breeder or store. Fish can be sick and have bacterial, viral, or parasitic infections that can be contagious to other fish in the pond. 

If you are able to see the fish in person, observe all of the fish in the tank, looking for any sign of sickness. If just one fish in the tank is sick, it could be due to stress or other factors, and the other fish may be fine. The sick fish may just need to be watched closely in quarantine. Ask the store how long ago the fish arrived. Fish are more prone to illness right after shipping due to stress. Koi and other fish will need time to recover before relocating again.

How to Add Fish to Your Pond

If you're adding fish to an existing pond:

First step: Quarantine

Even if your new fish look healthy, they could be carrying parasites or other illnesses that can infect the fish you already have. Set up a separate tank and quarantine your new fish for at least two weeks. Keep an eye on them and be on the lookout for any signs of sickness so you can quickly treat it.

If you're adding fish for the first time:

Skip to step 2: Slowly regulate the temperature

Fish typically come in a bag filled with water from the tank they were stored in. The water level of the pond or aquarium should be within 15 degrees of the water in the fish's bag. Let the fish float for at least 30 minutes on top of the water in the bag so the temperatures are the same. If the temperatures are too off, the fish can become very stressed and even go into shock, which can be fatal.

**If the pond is in direct sunlight, place a light towel over the bag and monitor it, so your fish doesn't overheat.**

Step 3: Scoop 

After 30 minutes, gently remove the fish with a net and place them into the pond or aquarium if you're quarantining. Watch your other fish for any signs of bullying or distress.

Step 4: Wait 24 hours before feeding. 

Because your fish are in a new environment, they need time to adjust. Wait a full day before feeding your fish to let them acclimate and destress. You can feed your other fish before introducing the new fish so they aren't hungry and upset about missing their meal.

Tip: Some fish get stressed in new environments and may try to "jump" out. You can add pond netting to prevent any escapes.

Fish are a fun addition to your pond. Koi and goldfish can grow very large and live for decades, becoming part of the family. There are many different colors and varieties of pond fish. Certain fish get along better than others, and some fish have special purposes like mosquito and algae prevention. Adding fish to your pond is easy with the right preparation. Your fish will enjoy their new home, and your pond will be full of new fins and faces.



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