From a total of 241 wild fishes of 18 species examined, one specimen with deformed inter-nostril epidermis was found in the finepatterned puffer, Takifugu poecilonotus. The specimen had a normal inter-nostril epidermis for the right nostril but the left nostril was deformed. Although the deformed nostril had two epidermal membranes, they were not combined. The other 9 specimens of the same species caught had normal epidermis. Deformity of the inter-nostril epidermis very rarely occurs in wild fishes. This finding is only the second one after striped puffer, Takifugu xanthopterus.
In the present study, induction of maturation and ovulation and subsequent artificial insemination were tried in the cultured two-year-old brood stock of yellowtail, Seriola quinqueradiata to acquire fertilized eggs from young fish. After confirming the yolk accumulation by monitoring oocyte diameter through ovarian biopsy, fish with oocyte sizes between 700 and 740μm.....were selected. A single injection of HCG (500 IU/kg BW) could induce oocyte maturation and ovulation after 48 hours in all the fish except one. Enough volume (212, 000 eggs/fish) of floating eggs was obtained by the artificial insemination performed just after ovulation.
Strain No. 442, which is capable of producing an antibacterial substance against pathogenic vibrios, were isolated from an intestinal tract of Japanese flounder and examined for their taxonomic status. The 16S rDNA of strain No. 442 (corresponding to positions 18-1470 in the E, coli rDNA sequence) was sequenced and analyzed. Both phenotypic and phylogenetic analyses strongly suggested that strain No. 442 is identical to Vibrio proteolyticus.
We determined biliary bile salts levels in red sea bream fed on either fish meal or alternative soybean meal for 33 weeks. The feeding of soybean meal showed smaller body weight gain and higher mortality. No significant difference was observed in hematological parameters such as hematocrit value, plasma enzyme activities, and protein level between the groups. However, the biliary bile salts concentration in soybean meal group was significantly decreased following the reduction of plasma cholesterol and taurine levels, when compared to that in fish meal group.
A disease with mortality was observed in Japanese black abalone (Nordotis discus discus; 3+ -year old) reared at Kobe city sea-farming center in 1997. The diseased abalone showed a characteristic clinical sign of raising shell and died. There was no parasite in the gill or peduncle tissue. No significant microorganism was isolated from the peduncle tissue by bacteriological media. The disease sign was produced in healthy abalone by cohabitation with diseased abalone, but the disease was not reproduced by immersing 0.45μm-filtered homogenate of disease abalone. Histopathological examinations revealed that abundant heteromorphic cells were scattering in the muscular tissue of diseased abalone. In these heteromorphic cells, a lot of coccus like fine granules, negatively stained with Gram stain were observed. From these findings, it was considered that this case should be an infectious disease and the causative agent might be a kind of intracellular microorganism observed as the fine granules in the heteromorphic cells.