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  Today Online 23 Aug 06
Fish 'n' herbs
Sheralyn Tay sheralyn@newstoday.com.sg

FISH and basil usually make a perfect combination for a meal. But a thriving aquaponics set-up at Ngee Ann Polytechnic proves that they also make excellent partners in an ecosystem.

Aquaponics is the fusion of aquaculture, or the rearing of fish, and hydroponics, the cultivation of crops without soil.

Mr Gregory Chow, a lecturer at the School of Life Sciences and Chemical Technology, has started two aquaponics systems--one for basil and one for laksa leaf--in a pilot project early this year. Said to be the only such set-up in Singapore, each system consists of a fibreglass tank, water pump, waste tank and a plastic plant tray.

Each mini-ecosystem--about 10 square metres in area or the size of a small car--is home to some 200 red tilapia and crop of lush fragrant herbs.

"The idea," says Mr Chow, who has been experimenting with aquaponics since 2001, is to "feed the fish with protein food and they generate waste that will be transferred into a tank, which has bacteria inside that breaks down the waste into usable form. This is pumped into the plant trough and the water is recycled into the fish tank again." Symbiosis occurs--the plants "feed" on the nitrates in the fish waste, cleaning out the water for them.

Not all plants and fish can support each other this way, Mr Chow says. But here, the species have "reached equilibrium". That the system has proved to successfully grow "high value" crops such as basil and laksa leaf is a bonus, he says.

Other advantages is that this system is wholly organic--no artificial fertilizers are used. It is also very intensive, self-sustaining and cheap to install and run.

At NP, each system costs about $5,000, but the cost could be even lower if cheaper or recycled materials are used.
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