Fish poo to table food: the new farming method called aquaponics

Have you heard the one about nutrients from fish faeces feeding your lettuce? Didn’t think so.

“It’s a farming method that doesn’t damage or disturb the local environment,” says Italian-born chef Antonio Paladino, co-founder of Bioaqua Farm, the UK’s first commercial aquaponics farm that grows produce and rears rainbow trout.

Paladino was head chef at London’s Strada restaurant and in the kitchens at Hilton Park Lane, then he decided to escape to the countryside.

At a time when we’re constantly being told we need alternatives to meat to match our burgeoning protein demand (it’s really high), and insect cultivation is being touted as a solution (it definitely can be) by the UN’s Food and Agricultural Organisation, lesser known production methods such as aquaponics aren’t getting as much coverage.

Aquaponics is the marriage of aquaculture (farming fish and crustaceans) and hydroponics (cultivating plants in water without soil) in a symbiotic environment. Of course it’s slightly more technical, so let’s break down the science to make it more digestible.

The process works like this: fish are raised in tanks where they’re fed and do a lot of pooing, their wastewater flows out, it gets cleaned up a bit, the water is then pumped to growing beds, where it becomes food for plants.

aquaponics-chef-farming-somerset-bioAntonio Palandino lifting a tray of lettuce. Photo by Michael Segalov.

At Bioaqua’s setup on a plot of land in Somerset, aquaponics is part of a larger closed loop operation. Bedding from the duck coop is used as mulch to irrigate the orchard of apple and pear trees, water from the pond is used to water fruiting shrubs, and bees help to pollinate the orchard. They even eat the fish, unlike other farms.

Paladino and his business partner Amanda Heron supply Food Assemblies in Somerset and Bristol,  where they sell their trout pâté, fillets and salads and produce. The food is harvested fresh for same-day dispatch.

FoodAssembly-104 (resized)(2)     Palandio’s partner Amanda at the Frome Food Assembly in Somerset.


A question often asked at aquaponic experts is, does it make any difference to how fruit and vegetables taste? Paladino argues that both “the flavour and nutritional value are notably higher than [that grown by] conventional procedures”. This is thanks to the macro-nutrients and minerals in trout faeces, he adds.

What fish feed on is important. Just like continuously gorging on fast food and doughnuts isn’t going to do our stomachs, arteries or bowel movements any good, if fish are only fed protein and fat, they may break this down into ammonia but this will only be converted to nitrates. And though just nitrates might be enough to cultivate some leafy vegetables, other produce need macro and micro-nutrients in order to bloom. Therefore the fish need a balanced and varied diet.

aquaponics-farming-sustainableTrout reared on Paladino’s farm.

Calcium, phosphorous and potassium, for instance, can be got from mealworms and black soldier flies. Paladino says his trout are raised on certified organic feed.

A mark of how efficient a food system is, is how well it converts this feed into food. The problem with meat production is that it takes roughly five kilogrammes of feed (usually cereal, sometimes fishmeal) to produce a kilogramme of beef, and seven to produce a kilogramme of pork. In comparison, the input conversion ratio for aquaponic-grown food is minimal, says Paladino – as low as 1:1.

It’s believed that a third of all fish caught from the sea is ground into fishmeal for greedy pigs and gobbling chickens. Aquaponics is a way to put small aquatic animals to better use, and help keep sustainable food production swimming along nicely.

Also, the best thing about aquaponics is you don’t need much space. It removes the problem of requiring a large amount of space which is why it’s very common in cities and urban spaces. There are many great urban aquaponic farms like London’s Grow Up Farms, and Grow Bristol. Or just start one in your kitchen – watch your fish swim around in water while your plants grow. Easy.

About

Richard McEachran

Rich McEachran is a freelance features writer covering all things edible, green and sustainable. He writes for The Guardian, Vice and Virgin Travel. He was a finalist in the Guardian International Development Journalism competition 2012.

comments

  1. It isn’t really a closed loop operation if the food the trout are fed on comes in from outside.

    Given that trout eat flies and bugs and small fish and stuff in the wild it would be interesting to have learnt what these trout are fed on. Presumably some of their organic feed is derived from wild sea fish.

    Don’t get me wrong what they’re doing is admirable but it isn’t a closed loop.

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