Following the previous planning and after making the necessary arrangements, Dr. Salman Malekpour Kalbadi Nejad, the certain researcher of the Coldwater Fishes Research Center of Tonekabon, along with Mr. Taleghani, the head of the Organization of Agriculture - Jahad - Soleymanabad (Tonekabon County), Dr. Saraei and Mr. Kazemi, the regional experts of the Coldwater Fishes Research Center of Tonekabon, visited the cold water fish farm of Mr. Najafi in the Mian Daj Mahalleh Village. During this visit, various issues were discussed regarding the current conditions and aquaculture capacities. The farm is located in the southern part of the village. The water source of this farm was a well with an average temperature of 17 degrees Celsius and was equipped with an aeration tower and aeration system. The farm had 7 round ponds with diameters of 6, 8 and 10 meters and the height of 1 meter. The farm had a small earthen pool to introduce and stock fish juveniles and growing fish of various species including common carp, silver carp, bighead carp, grass carp, rainbow trout and sturgeons. The water from the round ponds was used for the earthen pool. Round pools were disinfected using chlorine solution and then the pools were washed thoroughly and kept dry. Fish feed produced by Faradaneh Company was used to feed the fish. According to the protocol, dietary supplements such as vitamin C and multivitamins as well as antibiotics, thyme and alfalfa were used. The 46 - year experience of the farm manager, as well as the participation of his daughter, who is a PhD student in fisheries sciences, has improved the conditions for keeping and raising fish. It should be noted that the main problems observed during this visit included the following:
The farm manager was not aware of the exact amount of water flow rate entering the farm,
The farm manager was not aware of the status of the physical and chemical parameters of the water,
Keeping several different species together at the same time and at different time intervals and the possibility of causing diseases and transmitting them to other species,
Increasing the temperature of the farm water to about 24 degrees Celsius which is very harmful for cold water fish,
At the end of the visit, the following technical recommendations were provided:
Assessment of physical and chemical parameters of water with the presence of the relevant expert,
Installing a thermometer at the water inlet and outlet of the farm to record the daily water temperature and find out the average temperature changes during different seasons of the year, which plays an important role in managing the amount of feed consumed by fish and thus the cost of production,
Using the salt bath to disinfect fish juveniles before introducing them to pools,
Installation of oxygen and ozone generators at the water inlet and drum filter to use the recycled water.