Farming of fish in cages Select site
Different criteria should be considered before selecting a site for cage cultivation. Physicochemical parameters such as temperature, salinity, oxygen, wave, pollution, algal blooms, water exchange, etc., determine whether species can reproduce in the environment. Other criteria to consider for site selection are weather conditions, shelter, depth, and temperament. Finally, you should consider legal aspects, access, proximity to hatcheries or fish tanks, security, economic, social and market considerations.
The fact that the cost per unit volume decreases as the cage size increases within the limits of the materials and construction methods used. CMFRI developed 6m diameter and 15m diameter open sea cages to grow fish farming and 2m diameter HDPE cages for seed breeding. Due to easy cage and reduced labor, the ideal size for cultivation cage is 6m. For fingering, a 2m cage can be used.
Cage frame and net
Various cage materials are available for cage farms. Commonly used materials are high-density polyethylene (HDPE), galvanized iron (GI) pipes, PVC pipes, etc. HDPE frames are expensive but long-lasting. For small groups and fishermen, a cost-effective epoxy-coated galvanized iron (GI) frame is recommended. GI frames have a shorter lifespan than HDPE frames. Nets of various sizes and materials were tested for cage culture in India. CMFRI used twisted and twisted HDPE nets for growth purposes. It can last more than two seasons. Nylon nets can be used economically, but they have a lighter weight, so more weight must be loaded into the ballast pipe to maintain their shape. While using a new netting material such as sapphire or dynema material in the net cage, you need to pay attention to the cost factor. A net depth in the range of 2 to 5 m is ideal. For an open sea cage culture, a predator net is essential to prevent attacks by predators. Potential species and criteria for species selection for cage culture The choice of species for cage cultivation should be based on multiple biological criteria such as omnivores or predators, robustness, fast growth, efficient food conversion ability, availability of quality seeds, disease resistance, and market demand.
Seed density should be determined by species requirements and operational considerations, but the effect of seed density on growth and production was determined empirically. Storage density also depends on our carrying capacity and feeding habits of cultured species. The optimal stocking density depends on the fish species and size.
Feed and feed management
Fresh or frozen waste fish, wet pellets (MP) and floating dry pellets are commonly used feeds for growing fish in our cages. Feeding in cages is very easy compared to feeding in ponds. The ration can be divided into equal parts and supplied at regular intervals. Broadcasts can be fed using the feed tray. The feed must be nutritionally complete and provide the proteins, carbohydrates, fats, vitamins, and minerals needed for growth and health. During storage, the feed cannot deteriorate.
Harvesting fish in our cages is less labor-intensive compared to in ponds. The floating cage can be towed to a convenient place, and full or partial harvest can be done depending on demand. As an added value, it is also possible to market fish under living conditions.
Cage culture management should optimize production at a minimal cost. Management must be so efficient that aquaculture fish grow at expected rates in relation to feed rates and stockpile density, minimize losses by diseases and predators, monitor environmental parameters and maintain the efficiency of technological facilities. Physical maintenance of the cage structure is also very important. The net cage should be checked regularly. Repairs and adjustments to the fixing rope and the net cage should be carried out without delay. You should also consider changing your net every month as it ensures good water exchange of the net, so you can wash your stool, uneaten food and reduce the impact of fouling to some extent.
Cage net foul
In many cases of cage farming, the fouling of cage nets and other structures has been observed. The net is covered with bio-fowler. Fouling by mollusks, especially edible oysters and sand barnacles, should be checked before growth. Algae mats and other periphytons can be removed by introducing omnivorous vinegar into the cage. Contaminated nets are heavier, increasing drag and losing nets and fish. To avoid/reduce fouling, the net needs to be changed when needed and can vary from 2 to 4 weeks depending on the fouling strength. During oyster fouling, a net exchange should take place immediately after the seasonal spat drop. Biofowlers can be controlled using herbivore fish such as rabbitfish (Siganus spp.), Capricorn (Etroplus suratensis) and scat (Scatophagus sp.), But large-scale applications need to be evaluated.
Monitoring fish health is essential, and early signs are often seen, especially in changes in behavior during feeding. summary Cage culture is the most efficient way to raise fish Cages can be built in a variety of appropriate water bodies of various sizes and shapes The stocking density of fish in the cage depends on the farmed species and the growth rate of the fish A cage can produce 20-40kg / m3 under normal conditions Identify ideal places essential for cage farming A proper feed with the most important quality feed for successful cage farming Regular monitoring of net cages and fish ensures a good harvest from us.