Aquaponics is the use of waste produced by fresh water fish, shrimp, prawns, crabs or lobsters to grow plants. Live fish are used to make fertilizer which produces ammonia that is high in nitrogen and is essential for plant growth. In return, the plants filter the water so that fish can live in it.
Tilapia is the most famous fish that reproduces and grows fast in an aquaponic system, but you can even start with a pair of goldfish. You can either leave the plants floating on the top of your tank or direct the water through pipes using an air pump to your grow-bed that holds plants with a growing medium. Water is then directed back into the tank to complete the tank cycle.
“Aquaponics is a quick, simple and cheap way of growing your food, and you don’t even need a green thumb!” says Abdul Aleem Shekhani, an aquaponicer from Karachi. Shekhani set up his first system in 2010 using his mother, Nasreen Ashraf’s storage boxes and store-bought PVC pipes, fish and other aquarium equipment. After two years, he upgraded his system and bought used bathtubs to turn them into a fish tank. The garden now produces everything from tilapia to cherry tomatoes to giant melons, unlimited sponge gourd, lots of basil and oregano. The set-up can cost anywhere between Rs1,200 and Rs1,500 and may even be cheaper if you reuse supplies.
“The only thing I do regularly is feed the fish and harvest vegetables when they are ready,” says Ashraf who also has a rooftop kitchen garden which needs much more work. “Vegetables that I grow using aquaponics have larger, greener and healthier leaves compared to the ones in the pots.”
Even though the method is relatively new, it is picking momentum globally. Ellezerdo Sarsalejo is a Philippines-based aquaponicer, who lives a few miles away from where the typhoon hit last year. He built a system using PVC pipes, barrels and large water bottles. Unlike Nasreen and Aleem, he did not use any edible fish. Within 75 days of starting his backyard aquaponic system, Sarsalejo was able to harvest dozens of bitter gourd which is remarkably quick. “You can double or triple your harvest if you have a good system,” he says. “I started an aquaponic system back in September 2011 as an experiment and since then it has been very successful.” Now Sarsalejo grows all kinds of vegetables and herbs, including cherry tomatoes, lettuce, basil, eggplants, huge beans, okra and bitter gourds that grow fast using his aquaponic set-up.
It is a well-known fact that during 1150-1350 CE, Chinampas — an ancient agricultural method which used rectangular areas of fertile land to grow crops on shallow lake beds — produced one-half to two-thirds of the food consumed by the city of Tenochtitlan, including maize, squashes, amaranth, tomatoes, peppers and beans. Hence, aquaponicers might be justified in claiming that the method can feed the world one day.
Zahra Ali Husain is a sustainability education specialist, writer and an environmentalist. She tweets @Zahrali
Published in The Express Tribune, Sunday Magazine, February 23rd, 2014.