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Adding fish to a pond without a pump or filter is often frowned upon by pond enthusiasts.
And for many reasons - they might not get the oxygen they need, their excrement will dirty the water and cause algae to grow, and so on.
But, like most things in life, the answer to this question isn't that simple.
So, let's break down this topic and look at whether adding fish, particularly goldfish and other popular pond fish, to a pond without a pump is a good idea or not.
Do I Need A Pond Pump For Goldfish?
No, you do not need a pond pump for goldfish if your natural pond (no pump or filter) is set up properly.
In other words...
Goldfish can survive and even thrive in a pond with no filter or pump as long as you have a properly planted pond and don't overstock your pond with goldfish.
This seems to go against the advice of many, especially pond product manufacturers who want you to buy their latest pumps and filters!
But, with the proper setup, you can successfully stock your natural pond with goldfish. Here are a few things to keep in mind to have the healthiest natural pond and goldfish possible.
Tips For A Pumpless Goldfish Pond
- Make sure your pond has a lot of oxygenating pond plants! This is extremely important to help supply much-needed oxygen to the water and to consume nutrients (goldfish poop, for example) that would otherwise fuel algae growth.
- A mix of submerged, emergent and floating pond plants is ideal. And you want 2/3 of your pond to be covered by floating plants, like water lilies, to block UV light from reaching any algae.
- Line the sides of your pond with rocks to create more surface area for beneficial bacteria to grow on.
- Don't overstock your pond with goldfish. And keep in mind that they will breed (and sometimes fast). So, you may have to scoop some out and give them away if it gets out of hand. If you have heron or other natural predators visiting your pond they may be able to help keep your goldfish population under control.
- Do not feed your goldfish. Adding fish food to the water will only increase the number of nutrients that may fuel algae growth. Your goldfish will survive fine off mosquito larvae and other natural provisions.
- Do not use soil for your pond plants. Your plants do not need soil to grow in your pond. Instead, they will use the nutrients from your pond's micro-organisms to grow. Soil will just add more nutrients to the pond that you don't need.
- There's no need to clean the pond liner in this type of pond setup. In fact, the sludge and anaerobic bacteria on the bottom of the pond will help breakdown dead plant material and feed the growing plants. In your typical pond set up with a filtration system, aerator, and pump, you DO have to clean the bottom of the pond since aeration kills off anaerobic bacteria, and thus the sludge degrades very slowly.
- If you plan on overwintering your goldfish, you'll need to make sure they have a space near the bottom of the pond that won't completely freeze solid. It will also be a good idea to use a pond de-icer or manually keep a hole in the ice on the surface of the pond to allow for proper gas exchange.
As long as you follow these tips you should have no problems stocking goldfish in your pond without a pump or filter.
Keep in mind, you may notice some algae in your pond. This isn't a bad thing. In fact, having some algae is healthy in a pond. However, if you experience algae blooms then it's most likely because you either have too many fish or too little plants.
Can Other Pond Fish Survive Without A Pump?
Goldfish and other small pond fish can certainly survive in a pond without a pump or filter.
However, stocking a pond with koi or other large fish is a different story.
They are going to consume considerably more oxygen, create a lot more waste, and you will have to feed them which will in turn just add more algae growing nutrients to your pond. Oh, and koi like to eat your oxygenating pond plants...
That's not to say it's impossible, especially if you have a large pond and only a few koi.
But, we recommend you use a pond pump and a filter both if you want to stock large fish.