Fattening of Mud Crab (Scylla
serrata) in closed and open system
Zainoddin Jamari,
Fisheries Research Institute, Kg. Pulau Sayak
Kota Kuala Muda, Kedah, Malaysia
COMMON PRACTICES IN FATTENING OF MUD CRAB
Enclosed crab cages (box type)
Wooden/ Fiber glass tanks
Modified fish cages
Earthen pond
PRESENT VENTURE
Objectives
To determine the effectiveness of
closed system and open system
for mud crab fattening
- growth rate
- moulting frequency
- suitability of the system
• MATERIALS AND METHODS
Closed system
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Aquarium tanks - 8L water volume (160 tanks)
Mud crab (100 – 250g) wbw
Individual crab in each single tank
Salinity 25 ppt
Feed – trash fish – 5% of BW
Water flow - 100ml/min (V = 18vi d-1. )
Biological filter - 24 hours
Sampling/ data collection – weekly (BW and CL)
Moulting and survival rate were recorded on
daily basis
measured
Treated
Wild crabs
100ppm
Formalin
CL
BW
8L
Water inlet
sampling
Every week
- 7 weeks
Water outlet
Single crab
Open system
• Fibre glass tanks -180L (60 tanks)
• Mud crab (100 – 250g) wbw
• Treated with 100ppm Formalin for 1hr. Rinse with
brackish water and transfer into experimental tank
• Salinity 25 ppt ± 2
• Single crab in each tank/20L water volume
• Feed with trash fish – 5% of BW once a day
• 100% daily Water change
• Sampling for BW and CL on weekly basis
• Moulting and survival rate were recorded on daily basis
Open system
treated
20L water
weighed
Wild crabs
Daily checked
sampling
weight
Carapace
length
Water Q
check
Results
CLOSED SYSTEM
WEEK 1vs WEEK 0
WEEK 2 vs WEEK 0
15.0
15.0
T
10.0
10.0
T
5.0
0.0
1
13 25 37 49 61 73 85 97 109 121 133 145 157
-5.0
WEIGHT
WEIGHT
5.0
0.0
1
12 23 34 45 56 67 78 89 100 111 122 133 144 155
-5.0
-10.0
-10.0
-15.0
-15.0
TANKS
TANKS
WEEK 3 vs WEEK 0
WEEK 4 vs WEEK 0
20.0
25.0
15.0
20.0
15.0
5.0
0.0
-5.01 13 25 37 49 61 73 85 97 109121133145157
-10.0
WEIGHT
WEIGHT
10.0
10.0
5.0
0.0
-5.0
1 12 23 34 45 56 67 78 89 100111122133144155
-15.0
-10.0
-20.0
TANKS
-15.0
Growth (weight increased) vs time
TANKS
WEEK 5 VS WEEK 0
20.0
WEIGHT
15.0
10.0
5.0
0.0
-5.0
1
12
23
34
45
56
67
78
89
100 111 122 133 144 155
-10.0
-15.0
TANKS
week 6 vs week 0
50.0
40.0
weight (g
30.0
20.0
10.0
0.0
1
12
23
34
45
56
67
78
89 100 111 122 133 144 155
-10.0
-20.0
tank
Growth (weight increased) vs time
WEIGHTS FOR EVERY WEEK
130.0
WEIGHT
128.0
126.0
124.0
122.0
120.0
118.0
W1
W2
W3
W4
W5
W6
W7
WEEK
The average weight of the crab for every weeks.
CL
10.0
CL
8.0
6.0
4.0
2.0
0.0
W1
W2
W3
W4
W5
W6
WEEK
The average CL of the crab for every weeks
W7
Open System
WEEK 0-WEEK 2
30.0
25.0
25.0
20.0
20.0
15.0
WEIGHT
WEIGHT
WEEK 0-WEEK 1
15.0
10.0
10.0
5.0
5.0
0.0
0.0
-5.0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58
-10.0
TANK
TANK
WEEK 0-WEEK 4
25.0
35.0
20.0
30.0
15.0
25.0
WEIGHT
WEIGHT
WEEK 0-WEEK 3
10.0
5.0
0.0
-5.0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58
20.0
15.0
10.0
5.0
-10.0
0.0
-15.0
-5.0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58
TANK
TANK
w e ight gaine d
weight
20
15
10
5
0
w eek1
w eek2
w eek3
w eek4
w eek
average body w eight
weight (g
260
220
180
140
100
w eek 0
w eek1
w eek2
w eek
w eek3
w eek4
Moulting
• No moulting was recorded during the
experiment conducted for both system
Water Quality
Parameters
Closed
system
Open system
pH
5.5 – 8.0
5.5 – 8.0
Ammonia
n.d. – 2.0ppm
n.d. – 2.0ppm
Temperature
27 – 31 0C
27 – 31 0C
Salinity
25 ppt
25 ppt
Dissolved Oxygen
4.6 – 5.7
4.6 – 6.0
Alkalinity
90 – 110ppm
85 – 121 ppm
week
Closed system
Body weight
(g)
Carapace
length (cm)
Open system
Body weight (g)
Carapace
length (cm)
0
122.2a ± 30.2
8.4b ± 0.7
178.3c ± 32.9
10.42d ± 0.76
1
124.9a ± 31.6
8.4b ± 0.7
186.7c ± 41.4
10.42d ± 0.76
2
124.4a ± 30.7
8.4b ± 0.7
179.5c ± 40.7
10.42d ± 0.76
3
124.8a ± 32.3
8.4b ± 0.7
179.6c ± 41.5
10.42d ± 0.76
4
125.2a ± 32.5
8.4b ± 0.7
186.4c ± 42.1
10.42d ± 0.76
5
126.8a ± 32.9
8.4b ± 0.7
6
128.2a ± 31.5
8.4b ± 0.7
Discussion
• Crabs were showed inconsistent in weight
• The weight gained in the range 20% of
initial body weight
• Water quality was considered suitable
during the experiment
• Feed was well accepted
• Crab was noticed aggressive
CONCLUSION
Fattening crab in small volume using closed and
open system resulted of minimum growth (weight
increment).
The viability of these techniques to produce soft
shell crab or fattened crab is not yet successful.
Further study on the effect of salinity and
physical environment parameters (light,
temperature, etc) may lead to overcome the
viability of the project
Thank you