One of the first questions people ask about aquaponics is “Fish poop? Gross!” (Ok, that’s not a question.) But it is an astute concern. Let’s talk about what we currently know in the realm of aquaponic food safety.
Because of the scarcity of land and fresh water, aquaponics is very popular in Hawai’i. The University of Hawai’i has been busting its butt to get good data on AP food safety so that the state’s growers can get food safety certification and thus sell to grocery stores. This surge of righteous gumption puts Hawai’i on the cutting edge of aquaponic food safety knowledge. UH put out a landmark study last year checking the levels of coliform bacteria in aquaponic water on 11 farms on three different islands in Hawai’i (link here).
As you can see in the study, most farms had extremely low counts. There’s a legal limit to how many coliform bacteria can be in water sprinkled directly onto plants for irrigation– for the curious, it’s 235 cfu/ml. Most of the samples collected were down near zero. There was one farm that had a day that was by far the dirtiest of all samples collected– making it all the way up to around 110-115 cfu/ml, or almost half the legal limit. That upper limit of 235 cfu/ml, by the way, is the EPA cutoff for what’s safe to swim in. Agriculture borrowed that number because we’re too lazy, I mean efficient to replicate efforts already done elsewhere.
UH also developed some food safety “good agricultural practices” for aquaponics, which you can check out here. These are guidelines on how to keep your crop clean. They include common-sense things like only topping up your system with clean potable water, keeping out critters, and washing your hands that are important to follow on any kind of farm. Aquaponics gets a couple extra rules like “if you touch the roots, wash your hands before touching the leaves again” and using gloves when you’re digging around in gravel beds. (At least in Hawai’i, they tend to use volcanic cinders as the gravel, and it’s sharp and can cut. Sad times for eaters and workers.)
It’s one thing to grow things in your own garden with half-baked hygiene. But when you’re growing food for other people, that’s a very serious responsibility. I’ve had the pleasure of working with the scientists from University of Hawai’i as well as fellow Floridian Gina Cavaliero of Green Acre Aquaponics to keep developing good info on AP food safety. I’m hopeful that this work can both help aquaponics to gain wider acceptance with food certifying agencies, and result in information that helps aquaponics growers to do our best possible job.