Fish farming

As aquaculture is called the fish of freshwater fishing with traditional methods. For this one uses mainly artificial ponds that are managed carefully planned. In order for the fish farming is part of agriculture, especially livestock farming. Furthermore, it is seen as the "classic" branch of aquaculture.

Basic shapes

There are two basic forms of aquaculture, in essence,

• The carp farming ( KTW) is applied in large-scale carp ponds with stagnant water. Here are produced from mineral fertilizer substances through the food chain of an ecosystem at the end of fish that are fished for a particular system. The fish produced here are in addition to the carp, the tench, perch and pike. From an agricultural point of view corresponds to the carp pond farming of grazing, occasionally with supplementary feeding.
• In the trout pond farming ( FTW ) usually elongated ponds or concrete flows through the channels with cool, oxygen-rich fresh water. The fish are fed with artificial diet. The water provides for the removal of excrement. Contents are fish species from rivers, so rainbow trout, brook trout, char, grayling and Danube salmon rare. From an agricultural point of view corresponds to the trout pond farming a dense housing systems with pure feeding.

The aquaculture uses for individual purposes and methods other than the pure pond attitude. The Incubation and brood rearing is usually in plastic pools in breeding houses, carried their water supply mostly by well or spring water. Some companies specialize in the production of juvenile fish and keep them up for sale at breeding farms in circular tanks.

Aquaculture from an environmental perspective

The two forms of aquaculture are fundamentally different from the use of "natural food " at the KTW and artificial pellet feed in the FTW. Thus, they use different places in a productive fabric of the biosphere.

Carp farming

The carp farming uses with their natural food primary production at the site. The biomass produced by plant organisms (algae and macrophytes ) in the pond is directly through the food chain of the pond ecosystem to the end members of the production, the fish passed. On the way, zooplankton and worms and snails are involved in the benthos. In the production of pike and walleye also serve the carp and other small fish (eg roach and moderlieschen ) as a further intermediate elements. The base of the pond ecosystem form the mineral nutrients such as water and carbon dioxide for primary photosynthesis, nitrogen compounds such as ammonium and nitrate, phosphate and sulfate as the sulfur source for the further development of the biomass. These nutrients also take part in the biogeochemical cycles of the ecosystem and are sometimes deposited in the mud and brought in later periods of production back into circulation and used.

In general, the nutrients are already through the inflowing water is available, but also to intensify production in the form of mineral fertilizer or organic manure (sheep manure, cow manure, grass clippings ) was added. Although the fertilization of a water body leads to its eutrophication. However, this is desirable in carp ponds. Your negative consequences in lakes are largely eliminated by the design of a flat waters of a depth of about 1-2 m.

In addition to the fertilization is fed in classical KTW in the fall with corn or soy to condition the fish to survive the winter.

Trout fish farming

The trout pond farming uses water exclusively as a transport medium of oxygen in the pond and disposal of excreta and excreta of fish ( carbon dioxide and ammonium ). The food of the fish consists almost exclusively of industrially produced pellet feed with a guaranteed by the manufacturer percentage composition of protein, fat, carbohydrate and crude fiber and set levels of minerals, trace elements and vitamins.

Importantly, from an environmental perspective is the origin of the raw material of these pellets. They consist mostly of fish meal and fish oil. These are derived from marine fish that are not directly marketed for human consumption. So, the bottom fish sandeels ahead of Denmark ( not related to the eel) mass collected and processed in factories to meal and oil, which are then supplied as raw materials to the actual feed manufacturers with bottom trawls.

Thus, the trout pond economy is not actually a production of freshwater fishing, but a form of "refinement" of marine biomass. Thereby the conversion efficiency is always similar to that of this stage, the food pyramids is on the order of 1:10 ( rule of thumb ). Although the animal feed industry uses a lot because ( divided by increase feed conversion ratio ) to improve the food quotient, but can not fall below certain natural limits. One must not be fooled by the official feed ratio of about 1, ie for 1 kg increase in trout about 1 kg of dry food are needed. The dry feed itself but is exempt from 80 to 90% water content of marine fish, so the 1:10 rule to the end, but one filled approximately.

Thus, the ecological assessment of trout fish farming is associated with the overfishing of the oceans and the destruction of communities on the seabed.

Currently running quite promising studies to recruit the protein content in trout food from plant sources. As vegetable protein sources are: corn gluten, soy products, alfalfa meal, brewers dried yeast, flaxseed flour and wheat germ. It will attempt to emulate the amino acid frequencies of the fish meal by suitable mixing. At the same time experimenting with the carbohydrates and fat. From the growth of the fish produces a crop substitution of fish meal seems possible. Unclear so far is recoverable meat quality of trout.