Growing coffee and raising fish in a closed system

Scientists in Berlin are studying how to grow tomatoes and fish in a highly sustainable system, contributing to solving the current food scarcity at a low cost.

Speaking of fish - tomatoes, everyone thinks of canned fish and tomato sauce. When biologist Werner Kloas talks about 'fish-tomatoes' he thinks of a combination of fish farming tomato in a closed and sustainable production system to address food security.

Researchers at the Leibniz Institute for freshwater and inland fish farming (IGB) implement this project at a large lake in Berlin.'Aquaponik' means a combination of aquaculture (Aquakultur) and a plant without soil (Hydroponik).

The laboratory is a nursery, where there is a high-end fish tank, in the middle of a row of potted tomato plants. These pots are connected together by tubes and wires, the back is a biological wastewater treatment system and a bacterial filter funnel. The greenhouse is so warm that the steam condenses on the glass ceiling - this is also part of the cycle.

When Mr. Kloas picked up the screened net, a lot of colorful perch spotted up the water demanding food.'Our fish here grow under stress-free conditions, the density of perch in moderate tanks, not too much is not too sparse. The fish raised here seem to be interested in being cared for and cuddled, 'explained scientist Kloas.

Biologist Werner Kloas with tomatoes grown in his Aquaponik system near Berlin

Clean water is pumped into the tank, waste water and excretions of fish are taken out.'Wastewater contains Ammonium toxic. But bacteria have the ability to convert this poison into nitrate - and this is an optimal fertilizer for plants , "Kloas explained.

The water has been treated with nutrient-rich nutrients for plants grown into tomato pots and covered with the bare roots of tomatoes. Tomato plants grow without great soil development - they produce clean steam and condensation on the roof when cold. From here the drip water is collected by the pipe system back to the cycle and becomes clean water in the aquarium.

In fact, the idea of ​​Aquaponik has been around for decades and has been piloted in many parts of the world, even in some businesses.

Biologist Kloas said, 'We develop this system to get the most out of it, even here there is almost no need to add water.' The amount of water to be added is only about 3% of the total water. 'To produce 1 kg of tomatoes grown in Spain's Almeria region, up to 180 liters of water must be used, while by Aquaponik method only 35 liters of water is consumed and the area of ​​cultivated land is only one-fifth of that of cultivation. Field work. " Fish food also ensures low cost sustainability: mainly to spread the protein and maggots of flies.

If heating a greenhouse with heat from a biogas system or photovoltaic cells, as is being done at IGB, then the entire farming cycle will not generate emissions at all."Fast-growing fish provide a large amount of easily digestible and high-value protein," Kloas stressed.

It could even be more effective if the researchers successfully cultured the Amazon's giant freshwater Arapaimas fish - the fish after only a short period of more than two meters long and weighing over 100kg - in this model .

Kloas said: 'Our technology can contribute significantly to food security in the 21st century . ' In developing countries, at a cost of about 1,000 Euros, it is possible to create a basic system of specialized coating water tanks and pumps that can produce about 200kg of fish per year.

The EU has funded 6 million Euro to experts from Germany, Spain, Belgium and China to implement this method on a large scale to assess economic efficiency and continue to improve it.