Madsen Pirie

I knew something about hydroponics and a little about how aquatic animals are raised and developed, but I knew hardly anything about aquaponics, the process that combines the two in a kind of symbiosis.  It joins aquaculture to hydroponics.  The animals can be snails or crayfish, or more commonly freshwater fish.  Sometimes edible fish such as tilapia are used, and sometimes inedible ones such as goldfish of koi.  In the basic system bacteria are added to the water so that the ammonia in the fish excreta can be converted into nitrates.  The nitrates in turn nourish the plants that are grown separated from the fish to protect their roots.  In a normal tank the waste products from the fish would make their environment increasingly toxic, but the bacteria enable it to be converted into a mixture that nourishes plant life.

What sparked my interest was a story that Vietnamese fishermen in New Orleans East have turned to this process after the oil spill in the Gulf spoiled their fishing grounds.  They use koi and minnows to produce nutrients for healthy crops they sell locally.  The process uses water, oxygen, light, fish food, and electricity to power the pumps and filters and to oxygenate the water.  In other aquaponics centres edible fish are marketed as well as the plants.  The process uses less land and water than do conventional methods and can be done on quite a small scale in less developed economies as a valuable source of food and extra income.

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