Best Substrate for Outdoor Fish Ponds

Most pet fish live in either an indoor tank or outdoor pond. We already covered what the bottom of your tank should look like, but what about your pond? Ponds are much more diverse than tanks and can come in a variety of shapes, layouts and “all natural” finishes. What is the “healthiest” bottom for your pond is essentially the easiest to clean = nothing.

Yes, a plain bottom is aesthetically unpleasing, but a bare bottom pond is easiest for most owners to clean. Whatever substrate you have, rocks or stones or something else, as long as you clean it regularly, it is fine for your fish. If you don’t clean it regularly or thoroughly, pockets of anaerobic bacteria can start to grow, and it their ever disturbed, release hydrogen sulfide that can kill all your fish. However, we have come to find that most pond owners don’t clean their substrate regularly. Having a plain bottom makes cleaning easier! Who doesn’t like that?


How do I clean my pond bottom?

The easiest way is by using a pond vacuum. These items are specially designed to make cleaning ponds easy. Think of it similarly to a pond-size gravel siphon. If you don’t have access to a vacuum, use a long brush or stick to stir up the substrate on a regular basis. This will bring oxygen deep into the cracks and crevices, preventing anaerobic bacteria formation.

For more information on pond cleaning, use our handy checklist so all your daily, weekly, monthly and yearly tasks get done on time. Remember: water quality is the #1 influence on fish health! Regular maintenance is the best thing you can do to keep your pond healthy.


“But my ‘all natural’ mud bottom is just like their natural environment so it’s better for my fish.”

Like we said, whatever works for you and keeps your fish healthy is fine by us. Just keep in mind that trying to mimic a “wild” system in an artificial environment is usually incomplete. Most “wild” setups include multiple types of fish, invertebrates and commensals working together to make their environment hospitable for all. There is usually a constant flow of water, so unless your pond has a leak or your have the funds to set up a constant overflow, this is harder to maintain. Also, wild systems will lose fish constantly to predators and other diseases that you do not want to subject your pet fish too. Just because it is “all natural,” doesn’t mean it’s better.

Most outdoor fish, meaning koi and goldfish, have been bred over centuries to live in artificial environments. They are poorly suited to living in the wild because brightly colored fish are easiest to spot and eat. Don’t pretend to go “all natural” because you don’t want to clean your pond. If you don’t want to do it, hire someone to do it for you. Providing your fish a clean and healthy environment is the contract you signed when you picked them out at the store.

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