How many fish can I keep.

Hi its Lee from the Japanese Water Gardens, in this video I am going to be answering a question that I get asked almost every day.

It's a simple question but it certainly does not have a straightforward answer.

BOY DO I WISH IT DID!

Keep watching and I am going to try and answer how many fish can I keep in my pond?

TRY TO ANSWER.

In the old days of fishkeeping before the days of pumps and filters there was a simple formula that was often quoted.

You can keep 1” of fish for every square foot of surface area.

The basis of this formula was oxygen exchange at the surface.

To apply the formula you just needed to measure the length and width of the pond in feet.

You then multiplied them together to calculate the surface area.

You then divided the result by 4 the average length of a Goldfish and you had your answer.

So a pond 6ft by 5ft with no filter or pump could accommodate 30inch of fish, about 7 goldfish.

Now here is where things start to become vague.

Add an air pump and you can increase the number of fish by a significant margin. But as the number of fish increases you will start to get a buildup of ammonia, a toxic waste product excreted by the fish.

If the ammonia becomes concentrated in the water it will be harmful and possibly lethal to the fish.

In a modern pond there will be a biological filter designed to breakdown the ammonia into nitrites and nitrates, progressively less harmful compounds.

The more efficient the filter is the more ammonia it can breakdown and the more fish you can keep.

To further complicate the situation Goldfish and Koi are not the same. A 12” long Koi will need significantly more oxygen than 4 4” long goldfish and produce a significant amount more ammonia. A 12” long Koi will have a mass equivalent of approximately 30 goldfish.

So this old formula is of little use. It is far too simplistic to be relevant on a modern Koi pond with a good filtration system.

More elaborate formula do exist.

But they are a complete waste of time! The answer you would get has no importance to the average pond keeper.

The question of how many fish I can keep in a pond is actually a pointless question.

You can keep a huge amount of fish, if you have a massive filter, powerful aeration system and are prepared to do lots of regular water changes, but is this a sensible thing to do?

What if you have an electrical power failure or your pump malfunctions. How long will the fish survive?

Overcrowding is potentially a stress factor, the more fish you have, the more rapidly a disease or parasite will spread through the pond. .

The question that we should be asking is “How many fish should I have in my pond?”

When pushed for an answer I usually recommend 10 18” per 1,000 gallons.

Now I know others will disagree with this. But I believe that this number gives a good display.

Have less fish, but better fish. By that I mean don’t stock up your pond with lots of average, unremarkable fish.

Instead be selective. Be careful what you buy. Choose quality over quantity.

How many fish do you keep in your ponds?

Thank you for taking the time to watch this video. If you like what you see be sure to subscribe to the channel and give the video a thumbs up.

Its bye for now from Lee at the Japanese Water Gardens.

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