Nursery

Nursery is the intermediate phase between hatchery and grow-out. Crabs with 0.6-1.0 cm carapace width (CW) (Fig. 1) are cultured to 1.5-2.0 cm CW in net cages installed inside the pond (Fig. 2), in a pond fenced/lined with nets (Fig. 3), or in a pond provided with net fence along the dikes (Fig. 4). Some farmers prefer bigger crabs than 1.5-2.0 cm for stocking so crabs are further grown to 3.0-4.0 cm (Fig. 5) in ponds lined or fenced with nets or dikes installed with net fence (Phase 2) prior to stocking in grow-out ponds.

Phase 1 and 2 may be done one after the other separately or continuously using the same pond compartment. The culture period is 3-4 weeks in each phase depending on the desired size at harvest.

Fig. 2  Net cages installed inside the pond	Fig. 3 Pond fenced with nets
Fig. 4 Pond with net fence along the dikes	Fig 5. Mud crab with 3.0 cm carapace width

Procedure:

Phase 1

1. Install net cages after pond preparation and before water is admitted into the pond.   If net pens will be used instead of cages, install this prior to pond preparation. Admit water after pond preparation.
2. Add ribbon-like nets, bundled short straw (used as tying material) or dried twigs as shelters.
3. Stock crablets (0.6-1.0 cm) at 20-50 ind/m².
4. Feed crablets with minced low value fish, molluscs (meat of snails, clams, etc) and/or boiled chicken trash at satiation or 100-150% of total body weight per day. Divide the ration daily and feed to two feedings.
5. Change about 30% of water every spring tide or when needed and maintain water depth of at least 80 cm.
6. Harvest and sort crablets.

Phase 2

1. Install net around the pond perimeter or dike at an angle of 45º before or after pond preparation.
2. Stock the crablets (1.5-2.0 cm) at 5-10 ind/m².
3. Feed crablets with fish, molluscs (snails, small bivalves, etc), animal entrails and boiled corn at 50-80% of total body weight/day.
4. Follow 5 and 6 in Phase 1.