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How Many Fish Should You Keep in a 500-Gallon Pond?
In the fishkeeping hobby, aquarists who have ponds need to know there’s more to maintaining a pond than just having the right pond equipment. They should also remember all species enjoy having plenty of space to swim, relax, explore, hide, and spawn. There’s no such thing as giving fish too much space. A single goldfish will be happier and healthier in a 10-gallon tank complete with plants and substrate when compared to a fishbowl. The same rationale should be applied to a pond insofar as always avoiding overstock situations. If you have a backyard pond that can hold 500 gallons, you can introduce just one male and one female koi and they’ll enjoy having all that water to swim in. Naturally, most pond keepers will want to add more species, and this is what they need to keep in mind.
Think About Pond Volume and Surface Area
Unless you only intend to keep boring goldfish, your pond should have a depth of at least 36 inches for koi, but you may want to go a little deeper if possible so you can add plants for the enjoyment of the koi. The only pond that can be shallower than one meter would be one where only gobis, paradise fish, or mosquito fish will swim. The surface area is measured in square feet, and it will be taken into account along with depth in the estimations below.
Calculating Fish Per Area and Volume
The most common recommendation is one inch of fish per every 13 gallons—this is the volume calculation. The surface area calculation is one inch per square foot. It’s better to go with the lower of the two numbers, and you should also use the measurement of adult fish. In the case of koi, which can grow to 13 inches, we’re talking about a couple of koi if we consider 500 gallons. In a rectangular pond measuring four square feet, you wouldn’t want to keep four adult koi, so you go with volume calculation, which is lower.
The Dangers of Overcrowding Ponds
A lot can go wrong in a pond ecosystem if it gets overcrowded. For example—inadequate oxygenation levels, too much fish waste, elevated levels of nitrogen and carbon dioxide, and generally unhappy fish. A very important element in a pond that’s often overlooked is a sizable filter and skimmer. There’s no such thing as too much filtration in a pond. A filter like the PondMAX 3600 with a UV sterilizer is a great filter that can keep your pond crystal clear:
Introducing Species and Letting Them Adapt
If you have a large pond that holds thousands of gallons, don’t rush to introduce all the fish it can hold at one time. Remember to add living bacteria ongoing for 2 weeks when you add fish. Once the pond has been established, ideally with plants, you should add no more than two fish at a time. Give them a couple of weeks to go through the bacterial bloom, and make sure to monitor all the water chemicals on a daily basis so you can make adjustments as needed.
Whatever size pond you have and however many fish you keep, make sure you have all the essential koi pond supplies handy. At Aquatic Warehouse, we carry everything you need to properly maintain your pond and keep its inhabitants happy and healthy. Check out what we have to offer on our website, and don’t hesitate to give us a call with any questions at 858-467-9297.