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Learning Aquaponics (goto LETS Home)

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Fish Food
Grow Beds
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Rafts to Fish to Food

The Needs of Fish

Fish need from 1-3% of their bodyweight in food a day.

Fish by Kilograms to Litres Water.

lb of fish
3 - 5
Gal of water
kg of fish
11 - 19
litres of water
kg of fish
25 - 42
litres of water

1lb = 2.2kg

1 gal= 3.785 liters

The Needs of Plants

The general motabolism rate of fish is such that for every square meter of grow space you need to have 30-50gs of feed being given daily to the fish.

The calculations

This sounds convolouted but we would start with the grow area first.

As an example

You have 10 m2 of grow space.

So you want to be feeding 300g to 500g of food a day to what fish you have.

We will start with the fish getting 3% of their body weight a day in food. This will slowly go down as they gain weight, until you change the systems or until you harvest the fish.

If we start at the upper of 500g, being 3% of body weight then we want 16.6kg of fish weight to start with.

These fish need to live in a water volume of 16.6kg * 42 liters = 700 liters This is the starting weight, with a hinishing weight of 50kg. These fish need to live in a water volume of 50.0kg * 42 liters = 2,100 liters

Starting with a grow bed that is 10m^2 with a water depth of 150mm, the bed alone holds 1,500 liters add in a tote, tank or pond at 700 liters and you are well with in the range of these calculations.