Greenhouse Canada

From the Editor: December 2018

Fishing at the Royal Ag Winter Fair

November 22, 2018  By Greta Chiu

I made my first-ever trip to the Royal Agricultural Winter Fair this year. Hearing about the University of Guelph’s greenhouse and indoor farming display, I dropped by for a look.

The first thing I noticed was the fish – an aquaponics display of goldfish and tilapia, swimming and fertilizing the leafy greens next to the tank (which were being happily grown under LED lights and flowed into another U of G project).

As the exhibit sign defined it: “aquaponics is an ancient concept that uses circular biomass flows to produce fish and plants within a looped system…While there are several possible interpretations of the system, it is consistently defined as a symbiotic production relationship between an aquatic species and a hydroponic plant.” In the display, the fish tank used “water flow and airstones to keep oxygen levels high” for the fish. As explained by Daniela Piovesan from the University of Guelph, the visible white mat at the bottom of the tank helped draw nitrogen from the fish poop through a filtration process. The microbes in the next step help consume the fish waste and make the nutrients more bioavailable for the plants.


I didn’t realize how neat the lettuce was until I revisited these photos. It was a deep water culture trough – a hydroponic bed holding up floating rafts of propagation plugs. “The roots are suspended in the water and absorb nutrients in the solution,” said the sign.

With ever increasing interest in sustainable production, it’s no surprise that aquaponics have been getting a lot of attention, especially over the past decade. But as the display also notes, “few commercial-scale aquaponic farms exist in Canada.” Why might that be?

In a conversation with Charles Hayes of Advanced Treatment Technologies a few months ago, he mentioned that it was hard to find operations that took aquaponics to a large level and succeeded long-term. “With the traditional way with how aquaponics are set up, it makes it difficult to ramp up to true commercial scale and without problems,” he said.

Traditionally, it’s set up as single loops. Neither the plants nor the fish are in their optimal environments, he says, and when things go awry, especially on the fish side, they die really quick.

But Hayes has a solution. “What we do is we separate it, so you’ve got two loops instead of one. You’re still using the nutrients off the fish to grow the plants, but it allows you to grow both the organisms – both the animals and plants in their optimum environment.” It’s viable, but there’s a large emphasis on the design phase, plus choosing the right crops and fish. It’s complicated when two living organisms depend on each other but have other needs – much like us.

Note: Following the publication of the October 2018 issue, the Growcer has since clarified that their originally-stated unit price of $180k does not include training or installation.

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