Streptococcus agalactiae was isolated from cultured gilthead seabream, Sparus auratus L., and diseased wild Klunzinger's mullet, Liza klunzingeri (Day), in Kuwait Bay, Arabian Gulf. Isolates were catalase negative, β‐haemolytic, Gram‐positive cocci and serogroup B. Experimental infectivity trials with mullet and seabream brain isolates in Nile tilapia, Oreochromis niloticus L., caused 100 and 90% mortality, respectively, within 7 days post‐inoculation indicating virulent S. agalactiae as the bacterial pathogen responsible for the epizootic in Kuwait Bay.

No abstract

Studies were carried out to determine the effect of using the rotifer, Brachionus plicatilis (Muller) (S‐type), subjected to different treatments on the growth and survival of blue‐fin sea bream, Sparidentex hasta (Valenciennes), larvae. This was to illustrate the role of mixed algae added to the oil enrichments for the treatment of the rotifers to improve the sea bream larval survival. The highest sea bream larval survival (P < 0.05) was obtained while feeding the larvae with rotifers enriched in a mixture of algae plus half the recommended dose of Super Selco and DHA Protein Selco. No significant difference (P > 0.05) in the larval growth was observed between different treatments. However, larval survival was significantly high (P < 0.05) when rotifers were not treated with antibiotics. The results show that there is no need to use antibiotics to treat the rotifers before feeding the blue‐fin sea bream larvae, providing that the rinsing procedure for rotifers used in this study is followed.

No abstract

One of the disease problems that affect the production of tiger prawn Penaeus monodon Fabricius in brackish-water ponds is the chronic soft-shell syndrome, a condition in which the prawn shell is persistently soft for several weeks. To determine the extent of damage in affected prawns, the histopathology of this syndrome was studied using light microscopy, transmission and scanning electron microscopy, and histochemical determination of calcium. Light microscopic studies of the exoskeleton of soft and normal hard-shelled prawns showed several distinct layers: an outer epicuticle, a thick exocuticle and a thinner endocuticle overlying the epidermis. The cuticular layers of the soft shell often had a rough or wrinkled surface and were usually disrupted and separated from the epidermis while those of the hard shell were generally intact and attached to the epidermis. The exocuticle and endocuticle of the hard shell were considerably thicker than those of the soft shell. Ultrastructural observations revealed the presence of a very thin membranous layer under the endocuticle. Tegumental ducts and pore canals traversed the 4 cuticular layers and were distinctly observed as pore openings on the epicutlcle surface. The epicuticle had a bilaminar and non-lamellate structure. The exocuticle had more wldely-spaced lamellae consisting of fibers arranged In a more compact pattern than in the endocutlcle Hjstochemical determination of calcium was done In exoskeleton and hepatopancreas of soft-and hard-shelled prawns. The hepatopancreas of soft-shelled prawn stained more intensely for calcium than that of the hard-shelled one. There was no great difference in calcium content of hard and soft shell, although the former stained slightly more intensely. Histopathological changes in the hepatopancreas of soft-shelled prawns were also observed.