Aquaponic Math...

[Eric Warwick]

Does any one know the ratio of fish:plants. Murry Hallam said 1:1 for grow-bed to fish tank, but stocking densities also matter. (get it) Trout to be less stressed I believe would need less of a stocking density.

[TCLynx]

BYAP usually says to stock 20-25 fish per 500 liter grow bed.

 

The exact ratio of fish to plants is harder to define since the amount of nutrient provided is not necessarily related to the number of fish but the amount the fish eat so small fish are not going to be providing as much nutrient as they will when they get big.  Also, different types of plants will use different amounts of nutrients.  Like a single lettuce plant will not use anywhere as much nutrient as a 3 meter tomato bush will.

 

However, if you design a system along the lines of what Murry or Joel recommend and stock it as they recommend, you are likely to do ok.

 

And just because trout might need slightly lower stocking density doesn't mean they will not provide enough nutrients since trout need very high protein feeds which will provide more nutrients to the plants.

 

Just make sure you have plenty of bio filter for the amount of fish and fish tank and the rest of the balance can usually be adjusted over time to get it just right.

[Eric Warwick]

Thank you TCLnx, but if I would have trout live on insects, algae, and later herring. Would it affect the nutrients more than a processed feed that has 30% lipids(fat) Is there any Internet source from say the university of the virgin islands that calculates this stuff relative to their system? Also how has adding worms affected the plants if at all. 

TCLynx said:

BYAP usually says to stock 20-25 fish per 500 liter grow bed.

 

The exact ratio of fish to plants is harder to define since the amount of nutrient provided is not necessarily related to the number of fish but the amount the fish eat so small fish are not going to be providing as much nutrient as they will when they get big.  Also, different types of plants will use different amounts of nutrients.  Like a single lettuce plant will not use anywhere as much nutrient as a 3 meter tomato bush will.

 

However, if you design a system along the lines of what Murry or Joel recommend and stock it as they recommend, you are likely to do ok.

 

And just because trout might need slightly lower stocking density doesn't mean they will not provide enough nutrients since trout need very high protein feeds which will provide more nutrients to the plants.

 

Just make sure you have plenty of bio filter for the amount of fish and fish tank and the rest of the balance can usually be adjusted over time to get it just right.

[TCLynx]

Anything you add to the system will likely affect the nutrients some, however, I don't know of any studies that have figured out how to get proper nutrition to trout by using insects, algae and herring in a recirculating system.  See most universities and extension services study things that business and agriculture is likely to support and it can be difficult to get funding to do research studies into what you are asking about.

 

Now new Alchemy has done some research into some of this sort of thing but only very minimally and I don't know of any published papers that will tell you how to get proper nutrition to your fish and plants using insects, algae and herring in an aquaponics system.

You will be breaking new ground so keep good notes as they may help others.

 

Eric Warwick said:

Thank you TCLnx, but if I would have trout live on insects, algae, and later herring. Would it affect the nutrients more than a processed feed that has 30% lipids(fat) Is there any Internet source from say the university of the virgin islands that calculates this stuff relative to their system? Also how has adding worms affected the plants if at all. 

[Sylvia Bernstein]

Eric, you also might want to check out the Aquaponic Gardening Rules of Thumb in the top left of the home page here. I co-wrote these with Dr. Wilson Lennard, and they were endorsed by Murray Hallam and several experienced members in here. They are full of useful ratios.

[Eric Warwick]

What was the difference between your trout and tilapia in terms of biomass or how often you harvested? The years might be useful too for finding out the temperature. (outside in boulder)In any case reading closely at the guide was very helpful, one question I have is if the amount of gallons of water affects the rule of 1lb per 5-7 gallons?
Sylvia Bernstein said:

Eric, you also might want to check out the Aquaponic Gardening Rules of Thumb in the top left of the home page here. I co-wrote these with Dr. Wilson Lennard, and they were endorsed by Murray Hallam and several experienced members in here. They are full of useful ratios.

[TCLynx]

I would say yes in that you can't really grow out eating size fish in a tiny tank, as in you can't really grow out a full size trout in a 10 gallon aquarium even if it is only one trout.

Eric Warwick said:

What was the difference between your trout and tilapia in terms of biomass or how often you harvested? The years might be useful too for finding out the temperature. (outside in boulder)In any case reading closely at the guide was very helpful, one question I have is if the amount of gallons of water affects the rule of 1lb per 5-7 gallons?

[Sylvia Bernstein]

Eric, I gave away my trout to a friend in Niwot instead of growing them out to harvest size but I believe trout and tilapia grow at approximately the same rate.  I'm not sure I have your question clear about the fish / gallons, but if you are asking if the same rule applies to a small aquarium as a large tank the answer is philosophically "yes", but the next question is what is the minimum size tank you actually need to grow a fish out to a 1 lb size...and my understanding is that is about a 50 gallon tank.  SO realistically that rule only applies to 50 gallon tanks and larger.  Does that make sense?

[Eric Warwick]

Yes, I'm probably going to get a container with a pond liner. At least 250 gallons. TCLnx I think that ratio was what it said on the guide. Sylvia I was thinking more along the lines of more gallons of water from say backyard system to an commercial system.  

Sylvia Bernstein said:

Eric, I gave away my trout to a friend in Niwot instead of growing them out to harvest size but I believe trout and tilapia grow at approximately the same rate.  I'm not sure I have your question clear about the fish / gallons, but if you are asking if the same rule applies to a small aquarium as a large tank the answer is philosophically "yes", but the next question is what is the minimum size tank you actually need to grow a fish out to a 1 lb size...and my understanding is that is about a 50 gallon tank.  SO realistically that rule only applies to 50 gallon tanks and larger.  Does that make sense?

[TCLynx]

main difference between backyard to commercial systems is that in commercial operation they are usually trying to maximize profit just to pay the bills and therefore are often running really high stocking densities and therefore if anything goes wrong it could be a real disaster so they pay some one to be there every day and may invest more in backup and monitoring systems.

 

Of course in a backyard system the total amount of water is usually less and therefore the "buffer" period between when things start to change to when they are very bad can be less but the stocking people usually run in backyard systems is generally less which often makes up for the difference.

 

Make any sense?

 

For a first season with a system, start with a low stocking density and small fish so your system can cycle up and mature properly and you can hopefully avoid extra stress or fish kills.  Once the system matures you will be better able to judge the proper stocking for your system.

[Kobus Jooste]

Sorry to fall into a conversation that is quite some way down the line, but I think there are a few things about trout that make it quite a different culture option to the fish that typically have a lot of data and stocking densities available.  They like cold water with very high DO, plus their feed is likely to be well over 40% protein, which gives you a lot of waste to deal with in comparison to tilapia.  When you look at optimal temperatures for the fish compared to ideal nitrification temperature, you may find that you have to be a bit more conservative in your stocking densities or alternatively expand your amount of media bed in use.  I have not seen the rules of thumb calculator of late, but the first one did not ask for fish species in any of the inputs. You will see that the carnivores get a choice of protewin between 45 and 50%, which together with the Temp and DO that you will have to maintain for trout, will be the critical issues for me in the design of a trout AP system

[Eric Warwick]

I plan to cycle up with NH3 (ammonia) completely; then add rainbow trout from a undetermined supplier. How long does it usually take for the system to cycle up?   This says 40 days, is this true?
TCLynx said:

main difference between backyard to commercial systems is that in commercial operation they are usually trying to maximize profit just to pay the bills and therefore are often running really high stocking densities and therefore if anything goes wrong it could be a real disaster so they pay some one to be there every day and may invest more in backup and monitoring systems.

 

Of course in a backyard system the total amount of water is usually less and therefore the "buffer" period between when things start to change to when they are very bad can be less but the stocking people usually run in backyard systems is generally less which often makes up for the difference.

 

Make any sense?

 

For a first season with a system, start with a low stocking density and small fish so your system can cycle up and mature properly and you can hopefully avoid extra stress or fish kills.  Once the system matures you will be better able to judge the proper stocking for your system.

[Eric Warwick]

Yes; but I want to use trout because, I don't want to heat the water and I'll be growing them in a garage. I live in a temperate climate that rarely goes down past 25f or about -4c. I'll try and design my system that way. If I understand you correctly I should have lower plant matter compared to fish matter?

Kobus Jooste said:

Sorry to fall into a conversation that is quite some way down the line, but I think there are a few things about trout that make it quite a different culture option to the fish that typically have a lot of data and stocking densities available.  They like cold water with very high DO, plus their feed is likely to be well over 40% protein, which gives you a lot of waste to deal with in comparison to tilapia.  When you look at optimal temperatures for the fish compared to ideal nitrification temperature, you may find that you have to be a bit more conservative in your stocking densities or alternatively expand your amount of media bed in use.  I have not seen the rules of thumb calculator of late, but the first one did not ask for fish species in any of the inputs. You will see that the carnivores get a choice of protewin between 45 and 50%, which together with the Temp and DO that you will have to maintain for trout, will be the critical issues for me in the design of a trout AP system