Mud crabs (Scylla olivacea) fattening in recirculating aquaculture system (RAS) using vertical gallons crab house with different feed types

Abstract Long maintenance periods, availability of cultivation containers, and water quality management are generally issues in mud crab (Scylla olivacea) aquaculture. Recirculating aquaculture system (RAS) technology can be chosen as a solution to these problems. The objective of this research is to evaluate the effect of different feed types on the growth and survival of mud crabs reared using RAS. The RAS design utilizes small water gallons (20 L volume) as crab house arranged vertical on iron racks and connected with gravity-fed water systems. The water filter consists of charcoal, coral stone, sand, and seaweed (Gracillaria verrucose) installed at the bottom of the rack. The filtered water was pumped to the topmost part of the water gallon using a pump. The feed treatments consist of (A) beef liver, (B) tilapia fish, (C) squid, (D) clam meat. The results show that different feed types do not significantly (P<0.05) affect the growth and survival of both male and female mud crabs. Over a period of 14 days, the weight gain of crabs in all treatments ranged from 7.08 to 11.15 g for males and 7.61 to 9.91 g for females. Survival rates ranged between 65% and 80% for males and between 85% and 95% for females. Water quality during the rearing period was at a temperature of 26-31°C, pH of 6.33-7.87, and salinity of 15-31 ppt. RAS in this study can be used for the short-term cultivation of mud crabs in limited space with optimal water quality.