Aquaculture is not aquaponics

Actually, today we consume much more fish than there is in the oceans and lakes.

Aquacultures in the seas and lakes are the basis for the high fish consumption. Today, aquacultures seem to be the solution at all to cover the high demand for fish, but there are also negative consequences for humans and the environment, especially for organisms living in the water. It is clear that more than half of all fish products consumed worldwide already come from aquaculture.

But what exactly is aquaculture? Aquaculture or aquafarming is the systematic breeding and catching of fish, seafood, etc. in freshwater or seawater. However, there is a big difference compared to traditional fishing. In traditional fishing, fish are taken from public waters, whereas in aquafarming the individual fish species are kept in separate net pens where they are bred, fed and then caught.

This is done in the sea, in pens or in water tanks. The fish are therefore the property of the keeper and can only stay in their net enclosure, unlike fish that are fished in the traditional way. There are many additional problems in free-range farming: the unconsumed feed simply falls to the bottom in the sea and above a certain quantity this leads to undesirable reactions from the environment.

The differences between the systems
It is already clear that in aquaculture and hydroponics, environmental aspects and a higher production volume play a decisive role. The systems pollute the oceans and farmland less with by-products and can also be operated without being tied to a specific location. The difference is this: Hydroponics is for growing plants, aquaculture for breeding animals.

In aquaponics, the two systems are combined to make the disadvantages of each work to the advantage of the other. Hardly any water is lost because the loops are almost closed - with the exception of the extracted material (obs, vegetables, fish, etc.), extremely little water leaves the system. This means that only a correspondingly small amount of water is actually used. In addition, fertiliser or nutrient solution does not have to be added to the system on a regular basis. Aquaponics can therefore also be described as a further development of aquaculture and hydroponics.

Aquaponics - Combined systems
Setting up an aquaculture system or a hydroponic system is not very complicated, and there are two possible approaches: to set them up separately or to build a combined system. In aquaponics systems, the advantages of the two systems described are simply combined. Plants are only grown in a substrate, the fish are kept in a large tank.

A substitute for soil is expanded clay, even if it is not cheap. Gravel, rock wool, coconut fibre or other materials are also possible, but require some testing, as not all plants tolerate all variants equally.

An essential part of the cycle is the collection tank for the hydroponic water in which the fish are ultimately kept. These are supplied with nutrients and oxygen by the plants. The excretions of the fish provide the plants with almost everything they need. The result is that, apart from a little water, no additives need to be used. The closed system works autonomously, except for a small water pump.

So much for the theory, here is an interesting study by the South Westphalia University of Applied Sciences that shows the entire problem of such a system in real life.