Bacterial Diseases Affecting the Cultured Sepia Officinalis Leading to Increase Mortality Rates in The Laboratory

The early growth, mortality rates and bacterial infections of the cultured Sepia Officinalis were experimentally studied in the laboratory. Two hundred eighty five sepia larvae were hatched and placed in a 100 liter capacity rectangular glass aquarium (filled with seawater) in the laboratory. The Sepia individuals (285 individuals) were divided into two groups the first fed on a mixture of amphipods, rotifers and artemia and the second group fed only on amphipods to follow their growth and mortality. The second group was observed to grow faster with length 6.76 ± 0.06mm and weight 0.11 ± 0.01gm than the first one. The survival rate was 100% by the end of the first week and decreased gradually by the end of the second week. The recorded mortality rate reached 49% by the day 15th, where they infected with bacterial disease of Vibrio alginolyticus. The clinical signs of the diseased S. Officinalis were lethargic condition, food fasting and multiple skin ulcers with white-gray discoloration were observed and appeared on the body. The main post mortem lesions were congestion of the internal organ, beside the presence of ascetic fluid. The mortality among the diseased Sepia was increased by age; however it may causes death of most individuals by increasing time more than two weeks. The findings of antibiotic sensitivity test cleared that the isolated V. alginolyticus was sensitive to amoxiclav (amoxicillin-clavulanate), streptomycin, ciprofloxacin and chlormphinicol. Controversially, it was resistant to oxytetracycline, tobramycin, gentamycine and enrofloxacin. Keywords: Sepia Officinalis - growth rate - mortality rate - bacterial infections