Ask A Farmer — Aquaponics


koi Joy, anger, grief, delight, worry, regret, fickleness, inflexibility, modesty, willfulness, candor, insolence – music from empty holes, mushrooms springing up in dampness, day and night replacing each other before us, and no one knows where they sprout from. Let it be! Let it be! [It is enough that] morning and evening we have them, and they are the means by which we live. Without them we would not exist; without us they would have nothing to take hold of. This comes close to the matter. But I do not know what makes them the way they are. It would seem as though they have some True Master, and yet I find no trace of him. He can act – that is certain. Yet I cannot see his form. He has identity but no form. —   Chuang Tzu

By Andrew Plack

Water cycles from the ocean up to the mountains as rain. Trees pull water from the sky. Roots pull water up from the Earth. Salmon return to their rivers and spawn. Their death is a great food for the forest. Fish waste is a potent fertilizer. These natural systems can be emulated in your backyard. The current word for combining fish culture and plant culture is “Aquaponics.”

The ancient peoples of the world have long combined animals, water and agriculture in a symbiosis of related  cultivation. Combining cycles of fish and plants in agriculture mimics natural exchanges all around us in our environment.

The Aztec people cultivated agricultural islands in a system considered by some to be an ancient  form of Aquaponics. Plants were raised on stationary, (and sometime movable), islands in lake shallows and waste materials dredged from the canals.

The integrated fish  culture of Southern China is a system in use for  Thousands of years. Written records from 200 B.C. have been found detailing the combination of plant animal and fish farming. There they grow a poly culture of fish species in ponds and lakes, fueled by ducks and pigs, which are raised next to the lakes.  Some systems are grass fed, others from aquatic plants. Bananas and other crops are grown alongside and in between bodies of water.

The ancient gardens of Babylon were stepped raised beds with a water pumping system that fed them water from the Euphrates river. These are the famous hanging gardens of Babylon, one of the wonders of the ancient world.

The modern systems basically have fish in a tank, and a table of medium or deep water through which the  water from the fish tank is pumped. The distinction of using a medium or deep water culture are the two most common methods of operation.

The table system with a medium such as 1” clean rock aggregate is often called ‘flush and drain’ because the water is pumped up to the table and allowed to slowly drain back into the fish tank.

The flush and drain method has the lowest energy input as it may only need to flush as little as once a day for a few minutes. Tables are often multiples of 4’x8′ to suit the layout of plywood based designs.

The deep water method consists of a table that is always full of water. The plants float upon rafts of material, often styrofoam or other synthetic material. The plants roots just hang in the water. The pump is always working to circulate the water. Solids are filtered out with a pre filter.

The fish can be any hardy species. Tilapia ,( a type of Chiclid), are very popular. Koi fish or even goldfish work well also. Prawns, crayfish and other fish species are also raised in the tanks or in the case of deep water tables, right under the floating plants themselves.

The rub comes from the fish feed. If you feed your fish often, you just found another way to pay for your produce. In addition, the feed is made from fish meal, corn and soy, all undesirable ingredients. One easy solution is a five-gallon bucket hung over the fish tank, used to grow worms, maggots or black fly larva. Another way to feed the fish is an LED light on at night near the fish tank. Insects fly into the water as the light reflected there attracts them.

Andrew Plack studies life and smiles on the Hamakua Coast.

1 reply
  1. Edy Hall
    Edy Hall says:

    I really like the LED light on at night, as a food source, idea. I’d never thought of that. That’s great. Thanks!

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