Page 48 - fish_farms_curriculum

give this amount of feed, the fish may be unappetizing on some days/meals. If the fish are not

getting the feed, feeding should be stopped and this should be noted.

The average weight of the fish should be noted monthly. For this process, 20-30 fish are
caught randomly from the fish tank according to the stock density, and the fish are transferred

into a container filled with tared water, after the water is filtered, and the total weight is
measured and recorded with a scale. By dividing the total amount of weight recorded by the

number of fish sampled, the average weight of one fish in tanks is determined. In tanks with

high stock density, this process can be repeated 2-3 times. The important point to be
considered while doing this process is to choose the fish randomly and to avoid taking

especially large or small fish while sampling. If necessary, the tank water level can be
lowered and sampling can be performed more easily.

Fish will grow after a certain period of time and will reach a greater weight than the weight in

the first place. However, not all fish will grow equally, some fish will grow faster, some will
remain smaller. This may happen due to the genetic origin of the fish, the pre-grading

processes carried out in the hatchery produced, or the success or failure of the fish in

accessing the feed. A large size difference in the same tank will affect the growth
performance of the fish in the tank, causing large and small fish to be harvested during the

harvesting of the fish. In order to prevent this, the fish should be sorted at certain time
intervals and the large and small fish in the same tank should be separated from each other.

This process is called fish grading. Mechanical grading devices or grading machines are
available for the fish grading process, but in low-tonnage enterprises, manual grading can be

done with two workers.

For this process, all the fish in the tank will be gathered aside with a long net with a lead rope

knitted bottom and a float on the top, through the appropriate mesh opening, and the other
part of the tank will be full of water but without fish. With the help of a small scoop, the fish

caught in a part of the tank are selected by hand and started to be separated according to their
size by eye. The excess group is left in the same tank, and the lesser group is moved to

another tank or a container filled with water. After this process is applied to all tanks, big fish
and small fish will have been separated from each other. The feed needed by both groups

should be calculated by taking the average weight as described before. Again, the feed

particle size should be determined according to the size of the fish.

During these processes, the fish collected at the edge of the tank should not be compressed too
much, they should be kept in such a way that they can swim freely but also be caught easily,

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