Ratio of Fish to Plants

[Bill Moore]

There is a fair amount of information on the ratio of fish to tank capacity, but I've not seen any discussion on the ratio of fish to plants.  How do you keep fish waste and plant nutrient needs in balance, especially in commercial systems where fish are growing and plants are being harvested?  

[Vlad Jovanovic]

Bill, I believe there are many discussion here as well as on some of the other forums (BYAP for ex.) on this topic. Many, many people as well as business' seem to use Dr. Lennards calculator to get an idea of such numbers. Dr. Lennard has been kind enough to allow us to download his calculator for free...http://www.aquaponic.com.au/backyard.htm

Here is an eco-films interview with the gentleman...http://www.ecofilms.com.au/2011/01/08/dr-wilson-lennard-on-commerci......Theres A TON of good AP articles/stuff on that site as well...so click away

And if you go to the Aquaponics Rules of Thumb  of this forums Homepage, there is a bit of info on that as well as a link to download that same calculator...(the first link was just me trying to expose you to some of the wonderful Aussie stuff, so click away there too if your bored LINKS, COMMERCIAL, BACKYARD, etc...tabs located on the AP solutions page...they are all good reads :)

Generally though you'll stock fish to your bio-filters capacity...then add more plants if you have the available nitrates...seems like a solid enough plan...

[TCLynx]

It can get complex though since seasonal temperature shifts will affect feeding of the fish which will affect the nutrients available for the plants.

And then some plants will use far more nutrients than other types of plants.

And then the type of system will affect how much nutrients are available to the plants in relation to the amount of fish since a system that removes solids will require more fish and more fish feeding for the plants relative to a system that keeps the solids in the system to be mineralized and turned into plant nutrients.

For example the UVI methods say you need X amount of fish food daily per square meter of plant bed while a different sort of operation might get away with far less.

The calculator is probably a fair place to start though.

[Vlad Jovanovic]

Definitely... Bill's growing indoors so hopefully the temp thing at least shouldn't matter much. And he's taken the trouble to build some pretty crazy heater(s) for his fish :)

Bill, you can find lots of info on the nutritional needs of different types of plants at different stages of their growth from a good book, or on the net even, to give you a rough idea/starting point.

It is probably wise to take any information/charts/calculators/ you might come across and think about the conditions under which the info was derived, and how it would apply or need to be modified (or not) to your particular settings/conditions/species incl. plants&fish/food source (% protein etc...) /feed conversion rates your able to achieve and a whole host of other particulars.... Not to make it more complicating than it needs to be, but ecosystems (man made or not) tend to be...well, rather complex when you start to get into the details. This of course is a very wonderful thing :)