In this article we will discuss about the Crab culture: Types and Mud crab culture.
3.Green mud crab
4.Red clow crab
5.Mud crab farming methods
Crab culture specially mud crab has been prepared in some Asian countries like india, Bangladesh, etc. Mud crab has huge demand and high price in international market. As a result, there are huge possibilities of earning foreign currency by exporting crabs. The main benefits of crab forming are:-
a) Low labour cost
b) Low production
c) Fast growth rate
Types of Crab:-
Crabs can be found in Estuaries & coastal areas. They are member of genius, seylla, There are 2 species of crab available. These are suitable for commercial production. They are Gran Mud Crab & Red Clow Crab.
Green Mud Crab:-
These are large in size, they can grow to a maximum size of 22c.m. & it can weight about 2kg.
Red Clow Crab:-
These are smaller in size than green mud crab . Thay are smaller in size than green mud crab. Thay can grow to maximum size of 12.7c.m. & weight about 1.2 k.g.
Mud Crab Farming Methods:-
Mud crab can be raised in the following two steps:-
1) Grow Out Forming
2) Fattening System
1) Graw are Forming:-
In grow out farming system, young crabs are raised and grown for a certain period of 5 to 6 months till reach marketing size and weight. The grow out forming system describe below:
(A) Culture Pond :-
This type of crab farming system generally pond based. The ponds are depends upon the production size generally ponds for crab farming size between 0.5- 2 Hector proper bundh & tidal water exchange is most be necessity small size pond are very suitable for crab farming.
Juvenile Crabs can be stocked that weight around 10-100gm. In commercial production with supplimentary feeding 1-3 crabs can be stocked per square melur.
Mud crab can be feed with 10w cost fish shrimp etc. The crab should be provided 5% feed daily of their total body weight regular sampling is very necessary for monitoring the growth and generally health and to adjust the feeding rate.
Some pipes must be kept in the pond for sheeter of crabs. With in 3 to 5 month they will reach marketable weight and become suitable for selling.
(E) Fattening system:-
Rising soft shallow crab for a certain period untill their exoskeleton get harder is known as crab fattening system.
Hard shelled crab has 4 to 5 times more value in the market that. Soft shelled crab. Crab fattening business can be done by the following system.
(A) Fattening in Pond
(B) Fattening in cages /pans
(A) Fattening in Pond:-
The system is describe following below:-
Fattening can be done in any type of pond between 0.025 – 0.2 Hector. Size small tidal ponds with a depth of 1-1.5 meter is very suitable for crab farming. Pond preparation can be done by draching the pond water, sundrying and adding sufficient Quality of time. A fence is required around the pond for fattening purpose.
For stocking soft crab most be collected from the local Fisherman or crab merchant. The crab must be collected from the morning. 1-2 per square meter stunning density is ideal for crab flattening purpose. The ponds should be divided into different compartment action to size of crab and sex. Keeping male and female crab separate from each other which will ensure good result & reduce mutual attack.
Depending on season and crab availability 8 to 12 fattening cycle can be done in a year.
Generally crabs weight between 300-500gm is high demand and value in the market . All the crabs most be collected and sold when the reach the marketing weight and in a hard shelled conditions.
(B) Fattening in Pens/ cage :-
This can be described in the following heading:-
Crabs fattening can also be done in pans or floating net cage or become cage in a shallow estuarine water and inside large shrimp pond with good tidal water influx and in tank. The cage most be arranged in a raw so the crab can be easily feed and monitored.
Stocking density of locrabs per square meter and 5crabs per square mater in pans in ideal fattening in cage is only use in small shele production.
Water Quality/ Culture of Cross:-
Water culture plays a important role in production of crab. The water can be change proper medicine or chemical should be apply as per the following charts:
Salinity — 15 – 25%
Temperatures – 26°c – 30°c
Oxygen – un then 3ppm
pH – 7.8 to 8.3