Koi per gallon rule?

[Kim]

What is general rule for koi? I building a 750 gallon small raised pond and later on i'm building a 3500 gallon pond, how many koi could i have in each?

 

[Lisak1]

One opinion - 750 gallons is too small for koi. Goldfish are the way to go there.

For your larger pond - I'm a big proponent of under stocking a pond. You'll find various numbers and formulas to calculate the number of gallons per koi - find the lowest number and stay below that. You never hear anyone say "gee... I have way too much water in my pond and my fish are all sick/dying/dead!"

 

[Kim]

Ok great! Thanks. I started super small with a 125 gallon preformed pond with a few gold fish and just feel in love with it! So this weekend we are building a raised pond for my goldfish in the small pond

 

[Meyer Jordan]

Really it is the amount of bioconversion and the water flow rate that determine total fish load that a pond can accommodate.

 

[Smaug]

I have a 2500 gallon pond with well over 200 inches of combined koi and comets. I use a 4000 gph skimmer pump with about 10 gallons worth of bio/mechanical filtration. Fish are all healthy and have grown well. I concur that 750 gallons is too small for koi but you could easily raise several koi up to the age of about 3 then have your big pond ready. Just be sure you are ready and able to do that.

 

[Meyer Jordan]

The inherent flaw in the 'inches to gallons' rule is that fish weight (biomass) varies widely depending on size of fish Ten (10) 2" fish do not weight near what one (1) 20" fish does and that one (1) 20" fish produces 100 times the Ammonia of the ten (10) 2" fish combined per day.
Weight (biomass) determines amount of fish generated Ammonia. Biofiltration should be sized based on total daily Ammonia production (current or projected).

 

[Smaug]

I agree Meyer but it's about the only way it can really be talked about with us real people.

 

[Meyer Jordan]

I think that you are underestimating "real people".

 

[Smaug]

I will break down my fish list.
4 koi 20"
3 koi 15"
2 koi 12"
4 hybrid koi/comet 12"
8 comets 10"
Well,turns out I have almost 300 inches of fat healthy fish.

 

[Meyer Jordan]

I will break down my fish list.
4 koi 20"
3 koi 15"
2 koi 12"
4 hybrid koi/comet 12"
8 comets 10"
Well,turns out I have almost 300 inches of fat healthy fish.

And you obviously have the biofiltration to support them.
Your fish BTW, based on your reported measurements, are generating an average of about 3140 mg/L of Ammonia per day.

 

[RobAmy]

@Meyer Jordan Is there a way to calculate the bio filtration size for the Ammonia per day? I usually only ever see filtration described as gallons with fish load or without. I installed 3 Savio LivingPonds Versatile Filters plus my Savio Livingponds Waterfall Filter. I did this for extra Bio as my fish grow but honestly I just guessed. They claim for ponds up to 5000 gallons max size per filter. My pond is 3500 gallons so I have 20,000 gallons of filtration by their claim (I assume Savio max gallons is for none or very little fish load). I move approximately 8000 gallons with 3 pumps thru the filters.

I have 4500 gallons going thru the waterfall filter
I have 1800 gallons going thru 1 versatile filter
I have 1800 gallons going thru 2 versatile filters that are inline

Also my stream is approximately 19ft long and averages 4ft wide overall, which I assume does a bit of bio also. The stream has 6000gph plus going thru it

 

[Mucky_Waters]

Other critical factors that are just as important and need to be taken into consideration when making those calculations are PH, water temperature, and how much food is getting tossed into the pond every day. Even if the fish don't eat all the food it won't take long for that food to start getting converted to ammonia. This is why it is recommended that if you start detecting high ammonia levels that you immediately stop feeding your fish. Also the warmer the water is the more adverse effect the ammonia levels will have on the fish. Same goes for PH. "A useful rule of thumb is that at a pH of 8 ammonia is 10 times more toxic that at a pH of 7, and at 68 degrees Fahrenheit it is five times more toxic than at 32 degrees Fahrenheit." However, regarding PH the same sort of situation occurs with PH levels lower then 7.

You can have a pond that seems to be doing fine in cool weather, but if the pond water starts to warm up and the fish start getting active and you start feeding your fish a lot more food, things can go South pretty fast if you don't have the circulation and bio-filtration in place to handle it. This is especially true if your PH levels happen to be very high or low.
I don't know how many times I've seen people (usually kids) kill their aquarium fish simply by over feeding the fish, even though they had previously been doing fine.
For my pond, and probably for most ponds, the most critical time is early spring just as the ice is melting. The critical factors are; lower then normal PH in the spring, the water temperature is warming fast, the bioconversion (as Meyers likes to call it) is low, there is usually an excess of dead plant mater in the pond that is starts decomposing as the water warms which starts producing it's own ammonia, and the fish's immunity is weak. Now add to that the possibility that some over zealous fish keepers may notice their fish being more active and immediately start feeding their fish at mid summer feeding rations, and you end up with a recipe for disaster.

 

[cas]

@RobAmy, Meyer provided this information in another thread:

You can arrive at a working estimate of your total fish mass by using either-
http://www.russellwatergardens.com/koi-weight/
or
http://www.koiphen.com/forums/koicalcs.php?do=calcnh3c

You can get needed SSA using these conversions
1 SSA will convert 1 mg of Ammonia per day. 1 gram of fish weight produces 0.20 mg of Ammonia per day (based on 3% of weight/day feeding levels).

 

[Meyer Jordan]

@RobAmy, Meyer provided this information in another thread:

You can arrive at a working estimate of your total fish mass by using either-
http://www.russellwatergardens.com/koi-weight/
or
http://www.koiphen.com/forums/koicalcs.php?do=calcnh3c

You can get needed SSA using these conversions
1 SSA will convert 1 mg of Ammonia per day. 1 gram of fish weight produces 0.20 mg of Ammonia per day (based on 3% of weight/day feeding levels).

Thanks, cas! Someone has been taking notes

RobAmy, Outside of controlled laboratory conditions there is no truly pinpoint accurate method of determining, well, really any level of anything in an aquatic environment. Due to the intense dynamic nature of these systems and the myriad variables involved (as MuckyWaters pointed out earlier) conditions are in a constant state of flux. This is not to say that a close approximation or average, if you will, can not be determined. This applies to bioconversion requirements. Calculations can be made to determine the existing level of bioconversion (SSA), then the total fish load that can be supported, or, total fish load (present or projected) can be calculated to determine required bioconversion (SSA). Every submerged surface in a pond is to be included in the total SSA: liner, rock, the interior of all plumbing, skimmer and filter module housings, and plants (submerged portions). To this is added the SSA of the filter media in the biofilter. From this total a general determination of maximum Ammonia conversion can be realized.
I am sure that there may be more questions.

 

[cas]

Someone has been taking notes

Ha - you wouldn't believe how many! And as soon as you posted this I was looking up my numbers!