fish ratios

[Patrick Thomas]

The rule of thumb is alb of fish to 1 square foot of grow bed.  How do we accomodate the ratio when we are starting with fingerlings and fry sized fish?

[Jonathan Kadish NYC AA Chair]

That rule is misleading as it does not account for the size of the fish or the type of system you are growing in. If you have a media grow bed than you really would be fine with just one goldfish (2-3 inch) per square foot of grow bed. It doesn't take a lot of fish to grow healthy plants.

If you are growing fish for food then it gets more complicated.

[Alex Veidel]

The rule of thumb is 1 lb of fish per 5-10 gallons of water...it's a stocking density for what your fish will be comfortable with in an aquaponic system environment without additional aeration and filtration. It's not necessarily what your system will support, that depends on growing style and how much of a biofilter you have.

[Jeff S]

Isn't the grow bed the biofilter?  What is a general ratio for fish to GB? I'm trying to maximize fish in 500 gallons of water and maximize the amount of GB that the fish will support.

[Jonathan Kadish NYC AA Chair]

If you want to maximize the amount of fish in your system then you need to add additional filtration like a swirl/radial filter to take out solids so that you don't fill your grow beds with too much waste. If you have too much poo then you could end up with some stinky anaerobic grow beds and poor water conditions.

Jeff S said:

Isn't the grow bed the biofilter?  What is a general ratio for fish to GB? I'm trying to maximize fish in 500 gallons of water and maximize the amount of GB that the fish will support.

[Jeff S]

Increasing the size of the GB won't compensate for additional fish? Would adding worms to the system help?

Jonathan Kadish NYC AA Chair said:

If you want to maximize the amount of fish in your system then you need to add additional filtration like a swirl/radial filter to take out solids so that you don't fill your grow beds with too much waste. If you have too much poo then you could end up with some stinky anaerobic grow beds and poor water conditions.

Jeff S said:

Isn't the grow bed the biofilter?  What is a general ratio for fish to GB? I'm trying to maximize fish in 500 gallons of water and maximize the amount of GB that the fish will support.

[Jonathan Kadish NYC AA Chair]

Both would help, but if your goal is fish intensive it would be efficient to remove solids. A system without grow beds (DWC) where solids are removed can support more fish in the same footprint.

Jeff S said:

Increasing the size of the GB won't compensate for additional fish? Would adding worms to the system help?

Jonathan Kadish NYC AA Chair said:

If you want to maximize the amount of fish in your system then you need to add additional filtration like a swirl/radial filter to take out solids so that you don't fill your grow beds with too much waste. If you have too much poo then you could end up with some stinky anaerobic grow beds and poor water conditions.

Jeff S said:

Isn't the grow bed the biofilter?  What is a general ratio for fish to GB? I'm trying to maximize fish in 500 gallons of water and maximize the amount of GB that the fish will support.