Koi Stock Rates at Startup

[Burton]

Figured we might as well get this in a thread versus a wall comment to make it easier to find. And its easier for me to process all the information if I type it out.

 

 

Stock rates per sqft NOT gallons

From what I have found so far it seems the surface area is more valuable than the gallons in a system. Koi need room to move around and if they don't have this room they will be stressed. Using Sahid's suggestion of 1" to 2" per sqft of surface area for a IBC (40" x 48") with 300 gallons you can stock 13" to 26" of koi (1 to 2 koi at 12"). However if you got the ever popular rubbermaid 300 gallon tub you could stock it with 22" to 44" (2 to 4 koi at 12")

 

Another source for calculating stock rates http://www.koiandponds.com/fishstockingtable.htm

Using the same two tanks above (ignoring the gallons per koi chart and sticking to area only) the IBC would get Unfiltered 6.8", filtered 13.6", fancy filter (probably what AP is) 27.2" ... for the rubbermaid 300 gal tank Unfiltered 11", filtered 22", fancy filter 44"

So almost exactly what Sahib's 1" to 2" per sqft suggestion stated in the first example. So the base is pretty solid but how does it compare to stock rates, well it really depends on what your goal is on fish size, for me I want my fish to halt most of its growth at 12"

Growth rates and stock rates

If you "understock" a koi tank the fish will reach maturity at 12" and the growth rate will slow down as the koi focuse on reproduction. If you overstock a koi tank your fish reach maturity around 22"/24" ... The question is how much koi do you stock per sqft to reach the under stock number? Seems we turn to gallons now for the answer versus sqft.

 

http://www.atlantakoiclub.org/calendar/2006/January%202006%20presen...

This suggests a "low" stock rate is 1lb of koi per 100 gallons, medium stock rate as 1lb of koi per 50 gallons and a high stock rate of 1lb koi per 25 gallons of water. A 13" koi is about a pound. It should be noted the 100 gallons used is very filtered and optimal for koi health.

With this in mind if we look at the above two systems both would stock 3 x 13" koi and be understocked for each tank, granted the sqft should be used first to determine stock rates. Knowing this we can better gauge how many koi to stock given in one year they can be 12" long and if understocked they should almost halt their growing process. If you don't desire for your koi to stop growing at 12" then overstock your tank but know eventually you will have to find more sqft for the koi as they get larger.

My goal is to have a stable system with a more easily assessed end weight versus having to take some out and put them into another system, or sell them etc.

Filtration

Most koi owners do not have AP systems to filter their waste and have come up with. It almost seems silly to say X amount of koi per gallons of water because the amount of gallons in the the tank is not the gallons of water your koi live in. Your GPH X the amount of time its running a day is really the amount of gallons your koi is living in. Constantly keeping your pump moving water thorough your "filter" will be more important for smaller systems, however I think most everyone in AP would be considered on the "smaller system" side of this equation.

If using hydron with a SSA of 122ft2/ft3 and knowing from the pdf above each pound of koi needs 15 sqft of filtration we can assume our systems can support about 8.1 lbs per cubic foot of grow beds. Even using gravel at a SSA of 91ft2/ft3 you will have more than enough biofilter mass to handle koi. However if nitrates spike then we will obviously have a problem and need to plant more or get more beds. I don't foresee the need to worry about this too much till the fish are near end weight.

The greater concern will be aeration. The pdf above suggests using 10L/min of air per 300 gallons, now I dont think this means 300 gallons of tank but of system. Most likely there will be a need to adjust the L/min based on the total gallons in the system versus the tank. Special care should be taken to prevent any “dead zones” in the koi's tank. This means ensuring that each inch of water is moving in such a manner where it is filtered, and gets oxygen. Having more than one air-stone should be almost mandatory, and the more sqft you have in your tank the more stones you should have. You can notice dead spots by the debris on the bottom of the tank building up in certain areas and not others.

Questions for koi AP users

I am really curious to hear from people who have started new systems with koi and have had them a while to know how the nitrate levels were in the beginning, and since the system has matured. It seems stocking a 300 gallon systems with 2 to 4 koi the nitrates will be really low and might hinder plant growth. But I have heard some say koi produce a ton of ammonia versus other fish, non have ever provided any evidence for this however so I am curious.

 

I have a feeling the growth-bed cuft per lb of fish (or gallons) will be way off when it comes to koi given the room they require and the amount of ammonia they are reported to produce.

 

 

I hope someone finds this information useful, I know I will be returning to it when time comes to purchase my own koi :)

 

[Sahib Punjabi]

Hello Burton,

 

I have four Koi ponds, one for over 10 years, one about 1 1/2 year ,one started in last year in early August (circular pond 1,000 gal - actually maintained at around 750 gal), and one indoor 75 gallon tank (started in Nov 2010). The last two were stocked with very small Koi fingerlings, the 1,000 gal takn had about 200 2 to 3 inch while the 75 gal had about 75 1 to 2 inch.

 

You are correct that Koi produce a great deal of ammonia, far more than Tilapia or Channel Catfish (per my limited research so far). Initially I only planted a few plants in the AQ system run by the 1,000 gal pond (about 21 Basil and mixed greens 2 inch pots). However, the system cycled so well that in less than two months, I had virtually covered the whole 48x4 ft DWC grow bed as well as introduced a few NFTs and recirculating wicking beds. Now I had lost a few Koi (about 15 to 20 I think), to some wild life in late Nov and early Dec. hence I built a strong covered frame to keep these poachers out. The Koi are now around 4 to 7 inches and given that we are entering warmer weather, I am seeing an increase in plant growth (Nitrates and other measurements are all in acceptable ranges but I have noticed that the PH is slightly higher than I like...it is currently around 7.8 to 8.00). I am certain that I could double my grow beds this year (if I had the space), and double that next year given that Koi initially grow about 4 inches per year.

 

So what does one do...stock only a few Koi or GO FOR BROKE ! I had purchased the Koi in at special bulk price and mixed show quality. So what my wife and I have thought of is when the Koi get to 12 to 15 inch plus, we will contact the local Koi Society members and request that they assist in selling a half dozen or so every now and then via their auctions where we would donate 30 to 40 % of the selling price to a local charity, 10 to 15% to the Koi Society and the balance for us to help offest the expensive Koi Food costs :-)   Now given that some Koi command a premium collectors price, this should be an arrangement that should keep us financially happy.

 

God bless,   

[Burton]

I have been looking into koi alternatives and Shubunkin and Sarasa goldfish are interesting because their max sizes are 10" and 12" respectively. And being goldfish they produce a lot of waste as well.

300 gallon oval stock tank could get in more fish as the stocking rate is in pairs for minimal of 29 gallons or preferably 55 gallons. So 10 to 20 fish ... but 10 seems more reasonable in a 300 gal stock tank when they are grown out to 10" :D

[Sahib Punjabi]

Good idea :-)

 

Goldfish in general are more tolerant to lower oxygen levels than Koi and produce almost as much waste without growing as large as Koi (remember you do need lots of oxygen for good plant production). Personally I would go 30 to 40 % over the minimum ratio as one does have the occasional fish death / loss before you get to the optimal grow size. Also all fish do not grow in size equally.  

 

God bless,