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Fish health and disease
The most important way to maintain healthy fish in any aquaculture system is to monitor and observe them daily, noting their behaviour and physical appearance. Typically, this is done before, during and after feeding. Maintaining good water quality, including all of the parameters discussed above, makes the fish more resistant to parasites and disease by allowing the fishes’ natural immune system to fight off infections. This section discusses briefly key aspects of fish heath, including practical methods to identify unhealthy fish and prevent fish disease.
· Food and Agriculture Organization of the United NationsFish feed and nutrition
Components and nutrition of fish feed Fish require the correct balance of proteins, carbohydrates, fats, vitamins and minerals to grow and be healthy. This type of feed is considered a whole feed. Commercially available fish feed pellets are highly recommended for small-scale aquaponics, especially at the beginning. It is possible to create fish feed in locations that have limited access to manufactured feeds. However, these home-made feeds need special attention because they are often not whole feeds and may lack in essential nutritional components.
· Food and Agriculture Organization of the United NationsFish anatomy, physiology and reproduction
Fish anatomy Fish are a diverse group of vertebrate animals that have gills and live in water. A typical fish uses gills to obtain oxygen from the water, while at the same time releasing carbon dioxide and metabolic wastes (Figure 7.2). The typical fish is ectothermic, or cold-blooded, meaning that its body temperature fluctuates according to the water temperature. Fish have almost the same organs as terrestrial animals; however, they also possess a swim bladder.
· Food and Agriculture Organization of the United NationsExamples of small-scale aquaponic setups
Aquaponics has been used successfully in a wide range of locations. Moreover, aquaponic techniques have been revised to meet diverse needs and goals of farmers beyond the common IBC or barrel methods (described throughout this publication). There are many examples, but these were chosen to highlight the adaptability and diversity of the aquaponic discipline. Aquaponics for livelihood in Myanmar A pilot-scale aquaponic system was built in Myanmar to promote micro-scale farming during the implementation of an e-Women project funded by the Italian Development Cooperation.
· Food and Agriculture Organization of the United NationsEssential components of an aquaponic unit
All aquaponic systems share several common and essential components. These include: a fish tank, a mechanical filter, a biofilter, and hydroponic containers. All systems use energy to circulate water through pipes and plumbing while aerating the water. As introduced above, there are three main designs of the plant growing areas including: grow beds, grow pipes and grow canals. This section discusses the mandatory components, including the fish tanks, mechanical filter, biofilter, plumbing and pumps.
· Food and Agriculture Organization of the United NationsDeep water culture technique
The DWC method involves suspending plants in polystyrene sheets, with their roots hanging down into the water (Figures 4.68 and 4.69). This method is the most common for large commercial aquaponics growing one specific crop (typically lettuce, salad leaves or basil, Figure 4.70), and is more suitable for mechanization. On a small-scale, this technique is more complicated than media beds, and may not be suitable for some locations, especially where access to materials is limited.
· Food and Agriculture Organization of the United NationsCurrent applications of aquaponics
This final section briefly discusses some of the major applications of aquaponics seen around the world. This list is by no means exhaustive, but rather a small window into activities that are using the aquaponic concept. Appendix 6 includes further explanation as to where and in what contexts aquaponics is most applicable. Domestic/small-scale aquaponics Aquaponic units with a fish tank size of about 1 000 litres and growing space of about 3 m2 are considered small-scale, and are appropriate for domestic production for a family household (Figure 1.
· Food and Agriculture Organization of the United NationsComponent calculations and ratios
Aquaponic systems need to be balanced. The fish (and thus, fish feed) need to supply adequate nutrients for the plants; the plants need to filter the water for the fish. The biofilter needs to be large enough to process all of the fish wastes, and enough water volume is needed to circulate this system. This balance can be tricky to achieve in a new system, but this section provides helpful calculations to estimate the sizes of each of the components.
· Food and Agriculture Organization of the United NationsComparing aquaponic techniques
Table 4.2 below provides a quick reference and comparative summary of the various aquaponic culture systems described above. TABLE 4.2 Strengths and weaknesses of main aquaponic techniques System typeStrengthsWeaknessesMedia bed units Source: Food and Agriculture Organization of the United Nations, 2014, Christopher Somerville, Moti Cohen, Edoardo Pantanella, Austin Stankus and Alessandro Lovatelli, Small-scale aquaponic food production, http://www.fao.org/3/a-i4021e.pdf. Reproduced with permission.
· Food and Agriculture Organization of the United NationsBasic plant biology
This section comments briefly on the major parts of the plant and then discusses plant nutrition (Figure 6.3). Further discussion is outside the scope of this publication, but more information can be found in the section on Further Reading. Basic plant anatomy and function Roots Roots absorb water and minerals from the soil. Tiny root hairs stick out of the root, helping the absorption process. Roots help to anchor the plant in the soil, preventing it from falling over.
· Food and Agriculture Organization of the United Nations