Sitemaps

what is the density of fish2007-11-24 23:41:43Answers:

Density and growth

Density is a measure of the mass of fish per volume of tank space, usually in the units of (kg/m3). In nature charr can be seen in great shoals and one of the main assets/advantages of charr in farming is its adaptability to great density. Maximum density in charr farming depends on environmental factors such as water flow and temperature, which affect the maximum amount of available oxygen.The type of tanks also seems important, especially in regard of current and water exchange.

As the charr grows it seems to appreciate and thrive in great density.It is not unusual that density at ongrowing is 60-80 kg/m3 and there are many examples of good growth at twice that density.Better growth has actually been measured in farming at 50 kg/m3 than at 15 kg/m3. The explanation is probably change in behaviour, less strife and aggression at greater density as mentioned earlier. It is noteworthy that in spite of the great density, the fish is looking fine, without bite marks or wounds on the skin and fins.

In farming it is very important to make the most efficient use of the farming space and therefore the density of fish per farming unit or tank is of vital importance. This is especially significant, when farming in tanks where the volume unit is expensive when compared to farming in e.g. cages or ponds. The volume often becomes a limiting factor in the production capacity.

Density of charr in tanks can be very great without affecting growth negatively. It is common that the density is kept at 50-100 kg/m3 or more without trouble. Usually smaller fish are kept at less density than larger. It may therefore be convenient to start with fry at 30-50 kg/m3 and then let the density increase with the growth of the fish.If the tank is large, the initial density may be adjusted by setting the water level low at the beginning, slowly increasing it as the fish grows. If the density initially is low (less than 20 kg/m3), the size variability may possibly be kept at bay by feeding in the dark. The fight over feed and territory may be less in the dark then in daylight.