When selecting the production site, it is important to check the quality and quantity (volume) of available water, as well as the suitability of the site where the new fish farm is planned to be constructed. A rule of thumb is that about 10 litres/sec (600 litres/min) of water source should be calculated for each 1 tonne of rainbow trout produced.
In general, both cold surface and underground waters are good for trout farming. In the case of surface water, the daily (day and night) fluctuation in temperature maybe a few degrees (2–4 °C), while the seasonal (summer and winter) changes of water temperature may be as much as 5–15 °C. The temperature of springs and underground waters has no daily fluctuation and the differences between winter and summer are minimal if any.
The availability (quantity) of water may change considerably according to seasons, especially in the case of surface waters and springs. In dry seasons, the water supply may drastically reduce while heavy rains often cause floods and sudden increases in the water quantity of springs.
Therefore, the production capacity of a trout farm has to be planned according to the safe minimum quantity of water available. However, the protection of the farms against floods should be designed on the basis of the highest flood ever experienced. To reduce risk, a table of the seasonal fluctuation of the water source should be elaborated. In order to avoid flooding, the farm should be constructed in a location higher than the flood-affected areas. This can be done if water is taken and conveyed to the fish farm through a service canal.
Seasonal fluctuations in the quantity of available water
Note: The upper arrows indicate the levels of available maximum quantity of water and the lower arrows indicate the levels of available minimum quantity of water.
Importance of slope and soil quality in site selection
1. Slope of the site and arrangement of tanks It is important to select a site with substantial slopes. This will ensure the filling and drainage of the rearing tanks by gravity. 1.1 If a site has a gentle slope, the tanks can be arranged along it. 1.2 If the site has a steeper slope, the tanks should be arranged parallel to the slope.
2. Soil quality
The requirements for building a fish farm depend on the type of buildings and earth/concrete structures planned. For concrete tanks, the soil should be strong enough to hold the foundation of the tanks. For earth ponds, the structure, consistency* and permeability*of the soil should be suitable for building strong dykes.
Steps in the implementation of anew trout production unit or farm The entire future success of a new fish farm depends on how the different steps of construction are completed regardless of the size of the farm. If everything, including timing and budgeting, is well planned and prepared, considerable time and money can be saved.
Elaboration of engineering design and technical drawings is the first step after deciding to construct a new fish farm or production unit. Elaboration of the engineering plans is important and cannot be omitted. The benefits of a reliable engineering design are incomparably higher than the expenses of their elaboration, which is usually affordable.
Main steps in the construction of a new production unit or farm
The main steps of the construction of a new production unit or farm are: 1. Building of a strong shed to store construction materials and tools (later: feeds, equipment and tools). 2. Clearing the vegetation, removing objects from the site, as well as the topsoil where canals, tanks and ponds will be constructed.
3. Marking the planned structures with pegs. 4. Construction of canals, tanks, filters and a fish pond for bio filtering (optional), then installing and fitting devices.