Best Aquaculture Systems

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Aquaculture Systems Majorly Practiced

In this article I will be analyzing the two main fish farming systems namely extensive and intensive fish farming systems and in the process of analyzing I will look at the peculiarities which make one different from the other.

I have written other articles where I explained what aquaculture is and I also have an article written about fish farming, so for those who may be wondering what aquaculture or fish farming really is, please read my other articles on the subject matter. So now without wasting more time let us begin.

The major fish farming systems in practice are extensive and intensive fish farming systems, although some may identify a third which is semi intensive. This semi intensive fish farming system is somewhere in between extensive and intensive fish farming and sometimes may combine elements from both systems. 

However the wildly practiced and accepted systems by professionals in the aquaculture and fish farming industry are extensive and intensive fish farming aquaculture, and I will restrict this post to these two systems.

Extensive fish farming.

Extensive fish farming is all about mimicking the natural habitat of aquatic animals. In extensive systems, the environment where the fishes are reared are semi natural and this means that the fishes will feed on other organisms that grow naturally within the system i.e. algae, crustaceans and zooplankton. 
These organisms serve as food for the fishes being reared and are produced within the system. Both algae and zooplankton are produced by fertilization of the water body, and this fertilization is mainly done using animal waste. 

Extensive fish farming systems are uniquely identified by the minimal input of external supply that they require for production and are also identified by the huge utilization of crude protein sources like animal waste for feeding purposes. This system can contain a monoculture or polyculture of fish species. Generally in a polyculture of fish species under extensive system, there is always a boast in the fish yield due to the fact that the fishes being reared under polyculture system mostly occupy different ecological levels or niches within the system. 

What this means is that, there is little competition for food since the different fish species in the system have different feeding requirement. For example if the polyculture contains tilapia and carp or catfish, then tilapia will feed on algae while carp will feed on zooplankton and catfish being a benthic feeder can feed on other organisms found in the system as well.

A another plus of polyculture fish farming under extensive system, is that a natural balance is created in the system and maintained since the different species occupy different ecological niches or levels. An example of extensive fish farming is the pond system.

However one must be careful during fertilization of the pond not to over fertilize the pond leading to increase in algae pollution or algae bloom which pollutes the water and reduces the oxygen levels in it. When the water becomes polluted due to excess waste matter in the system resulting into an algae bloom or eutrophication, oxygen levels in the water reduce drastically and this can lead to mortality of the whole fishes.

Intensive fish farming system.

Intensive fish farming are know for their heavy reliance on external supplies for fish production. Intensive fish farms operate systems like the cage system, integrated recycling system (IRS) and the flow through or raceway system.

Fish feed mostly utilized under intensive aquaculture are commercial feeds that are high in protein, and this high levels of protein found in commercial fish feeds increases the feed efficiency and this results in higher feed conversion rate (FCR) which ultimately results to increased fish size. Given the feed efficiency and high FCR of commercial feeds used in intensive aquaculture, one will discover that fishes reared in intensive farms tend to be big in size and this is because 1.1 KG of feed will result in 1 KG of fish.

Also intensive aquaculture can be classified as being open or closed. In open systems like the cage systems  or the raceway systems, there is interaction between the system and the environment because the ponds are setup outdoor and in an open space, while in closed systems like the integrated recycling system (IRS), the tanks are setup indoor and there is no interaction with the environment since most (IRS) systems are mostly setup in greenhouses.

Most intensive fish farms requires a huge amount of capital to setup, for example the IRS system requires a very large capital to setup hence it is only used for frey and fingerling production.

Some constraint of intensive aquaculture is quality of feed and of water, to mitigate the problem of quality water, a aerator is used to ensure that the oxygen levels in the water are always kept high for proper growth and survival of fish, however it is observed that catfish generally does well under intensive cultivation because it can survive in waters with high levels of pollutants i.e fish waste. For this reason catfish are best suited for intensive aquaculture.

Conclusion.

Before choosing which systems to practice one should always consider the context for which the fishes are being produced, wither for subsistence or for commercial purpose. While one method or system might not be suitable for certain climes the same system might be suitable for others. 

For example, with extensive aquaculture even with its low fish yield limitations you find that it is wildly practiced in certain regions of the world e.g. In Europe, where you find that fishes are cultivated on large farms practicing extensive aquaculture despite it's drawbacks. No one method is superior to the other but rather the context under which fishes are being produced should be the deciding factor when choosing which system to adopt. 

Generally speaking intensive fish farms produce larger harvest of fish per unit area which are of marketable size and when compared with extensive aquaculture which produces low yeild per unit area, intensive aquaculture is suitable for rearing fishes for commercial purposes and the best choice system for aquaculture entrepreneurs.

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