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Fisheries > Culture Fisheries > Crabs

Different Methods of Crab Culture

Pond Culture

Pond size of 0.5 to 1 acre is most suitable for crab culture. However, large size ponds of more than one acre can also be used for this purpose. Sandy soils with a mixture of 50% clay are ideal for culture of these crabs. A water inlet system and an outlet system to drain out water during water exchange should be constructed as in the case of shrimps. The pond should be constructed in such a way that it should hold 3.5 to 4 feet of water towards the inlet and 4.5 to 5 feet towards the outlet. A flow through mechanism of water exchange should be there in order to remove any left over organic food material and also to efficiently remove excretory material. A fencing of nylon net used for fishing can be placed on the dike to prevent the escape of the crabs during nighttime. In addition, about 1000 numbers of stone ware, pipes of 6 inch diameter and 1.5 feet length, worn-out tyres, etc., should be kept at the bottom of the pond through out the dike. The nylon screen fencing should be supported with split bamboos of 1.5 m height around the pond periphery for preventing the escape of the crabs from climbing over the bunds. The maximum stocking density should be 1 crab/m2.

Crab culture in ponds

(Source: NIOT, Chennai)

Pen culture in Ponds

Several units of pens of 4 X 4 X 2.5 m could be made inside the ponds using bamboo strips which are driven 1-1.5 m deep into the soil to prevent the escape of the crabs by burrowing. The pens could be made nearer to the dykes for easy stocking and monitoring.

Crab culture in pens

(Source: NIOT, Chennai)

Pond culture in Mangrove areas

The ponds could be constructed as described above around the mangrove plants. But a maximum pond area of 100 m2 is suitable for this type of culture. A canal of 1 m wide and 0.5 m deep, in which water will be available even during low tide, should be dug around the edge of the pond. The centre of the pond forms a raised platform with mangrove vegetation, which the crabs would use as a refuge during low tide. Water exchange could be tidally controlled. Polythene nettings could be used to prevent the escape of the crabs. Feeding depends on the availability of organisms namely low-value fishes, mangrove snails, clams, mussels etc.

Pen culture in mangrove areas

The pens could be constructed using the locally available bamboo splits or arecanut logs or cane. These strips should be driven 1-1.5 m deep into the soil to keep the crabs inside and the potential predators outside. The manageable area of the pen could be 100 to 150 m2. With in the pen, a ditch of about 0.3 to 0.9 m wide and 0.3 m deep should be dug. Mangrove trees in the centre of the pen provide shade for the crabs. Roughly 1000 to 1500 crabs of 100 g each could be stocked per pen. The stocking should be continuous.

The crab could be fed once a day during high tide with low-cost fishes, mussels, clams, snails etc. The crabs could be harvested after 4–7 months. The crabs could be selectively harvested after they reach 400 g or more. Although this system is eco-friendly, survival rate of only 47 to 50 % could be expected. The loss could be mainly due to cannibalism, and escape of crabs. Lower stocking density is suggested to be a remedy for the low survival rate.

Pond culture of crabs in mangrove areas

Cage culture (suspended or fixed type)

Cage design

Crab fattening can be carried out in Cell-type Cane Cages of 1 m (L) X 1 m (W) X 20 cm (H) size, which can be partitioned into nine equal compartments. Each of these cages should be provided with a lid to prevent the escape of crabs. A gap of 5 mm is to be provided between the canes at the top and 2.5 cm at the sides of the cages to enable free movement of water through the cages. But, no gap should be provided at the bottom to enable easy movement of the crabs.

Crab culture in cages

(Source: NIOT, Chennai)

Stocking and feeding in cages

One crab should be placed in each compartment of the cages. In this method of fattening, higher number of crabs can be fattened in a square meter area, i.e. 9 crabs/m2 . Based on the local availability, different types of feeds such as trash fish, mussel, chicken waste, clams etc. can be given to the crabs.

Crabs stocked in individual cages

(Source: NIOT, Chennai)

Deployment of cages

These cages can either be suspended from a raft deployed in bays or backwaters or mangrove areas. These cages could also be made as a fixed type in ponds, mangrove areas or coastal regions of the bays. The cages could be made without cells inside. But the survival would reduce in this method due to cannibalism.

Deployment of cages

(Source: NIOT, Chennai)

Cage maintenance

  • Clean the cages as frequently as possible using brushes enabling free movement of water inside
  • If nails are used in the cages, use only the anodized MS/ copper / SS nails for increased longevity of cages in seawater.
  • Repair the damages in the cages immediately when it happens
  • Deploy the cages where there is mild water current
  • If algal growth is found on the crabs, clean them using a brush.


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