DEVELOPMENT OF FORMULATED FEED FOR MANGROVE CRAB Scylla spp.  

May Myat Noe Lwin*
School of Fisheries, Aquaculture and Aquatic Science
Auburn University,
Auburn, Alabama, U.S.A

Although the soft shell crab industry has been going for more than 20 years, little research has been done regarding formulated feeds and there is an urgent need to replace "trash fish" with manufactured diets. The present study evaluated a compounded feed for its acceptance and attempted to understand the preferred physical form of formulated feed by mangrove crabs, also commonly known as mud crabs, for better feed utilization. Wild caught crabs, sized 60-80g, were collected from one estuary and delivered to a farm in Ranong, Thailand.  A total of 600 crabs were randomly selected and placed into individual boxes with 150 boxed crabs stocked into each of four PVC pontoon rafts.  Three experimental diets and one control diet were randomly assigned to the crabs across the four rafts.   One group of 150 crabs were fed with a high fish meal content formulated diet, another 150 with high soybean meal diet, 150 with a commercial shrimp feed and 150 crabs were fed a traditional "trash fish" diet as the control group. Crabs were fed 3% of body weight split between two feedings a day in a 45 day feeding trial.

The commercial shrimp diet provided significantly better growth than the other diets, with an average growth rate of 0.89 g/day.   The trash fish control was not significantly different from the high fishmeal content diet, 0.80 g/day.  The high soy content diet was significantly lower, 0.72g/day.  However, the soy based diet had the highest survival rate (95%) versus shrimp feed at 91% and trash fish and high fishmeal at 85% each.  

Additional trials are planned in hopes of further increasing growth rates and survival.   Results may be available in time for presentation at the conference.