Management of nutrition, food storage and feeding of fish in cages
Food storage facilities
Consumption date and storage time of fish food produced by factories is between two to four months based on storage temperature. If food is stored for a long time or at high temperatures, the vitamins are destroyed and their oil is spoiled. Therefore, all cooked foods should be stored in a cool place. The barn should be well ventilated to store breeders and juveniles, refrigerators for dry and fortified foods, freezers to store Artemia cysts, frozen diets, and fish waste fed to breeders.
Fish in the cage environment are restricted due to confinement and lack of access to natural food. Live diets and low-value fish, wet food and concentrates are used to feed caged fish, and these types of foods have different advantages and disadvantages, which are summarized in the table below.
Therefore, feeding the fish begins after introducing the fish to the cage and adapting to the cage environment. In many cases, fish feed manufacturers provide food for a wide range of fish. Different species need different diets. Warm-water species (catfish, tilapia, carp, etc.) need 32% of protein, and cold-water species such as trout need 40 to 42% of protein in their diet. Improper feeding and feeding with low-value diets cause failure and failure in fish farming in cages. Avoid any disturbance and disturbance of water during the growing season. Moving the cage, catching fish, pulling the cage out of the water to watch the fish, swimming or fishing around the cage or placing the cage in a place that is disturbed for various reasons can cause stress in the fish, which in It eventually leads to disease. Cage feeding can be done manually or using automatic feeders or a system that monitors the feeding behavior of fish using long-tube feed transfer compressors. Each type of on-farm feed management has different disadvantages and advantages based on the labor used, application of technology, food wastage, monitoring of fish feeding behavior, cost and ease of use on site. For example, in the fish feeding behavior monitoring system, various types of electronic devices are used to monitor the feeding behavior of fish and uneaten food in the cage, such as cameras, food calculation software, infrared diagnostic system and water pumping system from the cage floor to transfer food. It is not used by fish and thus the amount of fish feed is measured based on the fish’s appetite and poured into the cage. Therefore, the software system calculates the amount of food in the next meal based on the input information obtained from the nutritional behavior of the fish and provides it to the breeders. In this system, the feeding behavior of all fish in the cage is evaluated to calculate the amount of future feeding, while in more traditional and rudimentary methods, only the number of fish that have come to the surface for feeding or the number of fish compared to other fish in Inside the cage are more dominant, it is considered to identify feeding behavior. The advantages of this advanced method include improving feed conversion ratio, reducing environmental pollution and evaluating all fish. In contrast, although this system is costly to set up, it is effective and can be used in all farms in the near future. To take. Floating foods with high buoyancy in the water column should be used to feed the fish, which will improve the fish’s vision during feeding. The feeding behavior of the fish can be a sign of good or bad water quality and the health performance of the fish. If the fish are not fed in the cage, the food will be out of the fish’s reach and will enter the environment outside the cage, thus increasing the environmental pollution of the area and causing economic losses to the breeders. Concentrate foods are available in different sizes. Finger fish are able to consume larger concentrate foods than smaller finger fish. We must always remember that the size of the food should fit the mouth of the fish. Fish are always actively feeding at or near the desired temperature range and when oxygen levels are high. Oxygen levels are high in the late afternoon, and it is very important that this time coincides with the feeding schedule. The general point to note is that fish will usually eat within 10 to 30 minutes when they are in the desired temperature range. Feeding less than necessary also slows down growth. At first, fish are very cautious in eating and usually adapt slowly. For this reason, it is recommended that you do not feed the fish for 2 days when the stress of moving and adapting to the new environment is present. Nutritional activity can be the best sign of fish health and growth. Feeding can be reduced for one to two days for reasons such as changing weather conditions or other disorders. If the downward trend in food consumption continues, other environmental and biological factors should be measured to prevent other hazards. Foods should be stored for less than three months, otherwise the main components of the diet, especially vitamin C, will be severely degraded in quality. Concentrated foods should be stored in a cool, dry environment. Never use fungal and moldy foods in your diet. Recording and recording the frequency and characteristics of feeding, like water quality and other factors affecting production, is very important and useful. With an accurate record, you can easily refer to the amount of food you eat daily and estimate its rate. Feeding is one of the most important cost factors in fish production. Wise feeding can be a rewarding and rewarding activity for the breeder. Avoid feeding in extreme heat and cold and during storms, because fish do not have a good appetite at these times. Get the fish used to feeding at specific times. Feeding is measured relative to the average length and weight of each fish, and food should be avoided in the dark or in turbid water.
General guidelines for food preservation and feeding
Food testing before storage
Cleaning the warehouse of any source of contamination
Store food in bags and place bags at high heights
Proper ventilation and temperature in the warehouse
Prevent insects and rodents from entering the storage environment
Inspect food for color, texture and odor during storage
Observing fish while eating: Eating behavior is the best sign to diagnose fish health. Actively eating fish means that everything is well done. Eating reluctantly and poorly can be questionable.
Decreased feeding when the water temperature exceeds the desired level of the breeding species.
Reduce or stop feeding on cloudy days (due to lack of oxygen)
Storage of food in cold and dry places (should be consumed within three months after production)
Never eat mushroomed or pale foods.
Record the amount of food consumed accurately.
Aquaculture Department: Seyed Reza Mortezaei and Hamid Ishaqzadeh
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