The intake and the tissue concentration of Sulfamonomethoxine were studied with Japanese anchovy (Engraulis japonica) fed with a diet containing Sulfamonomethoxine sodium. The intake of Sulfamonomethoxine sodium was calculated at 257mg/kg body weight (128.5%) from the whole body concentration of tested anchovy when the drug was orally administrated at a rate of 200 mg/kg estimated total fish weight. This high value of intake rate over 100% seemed to be due to an overestimation of total fish weight. The intake ranged from 181 to 355 mg/kg body weight, individual variations being relatively little. The tissue concentration of Sulfamonomethoxine was 2.5 mg% (Free) and 3.1 mg% (Total) 6 hours after administration, and 0.2 mg% (Free) and 0.8 mg% (Total) hours after 24.
The sensitivities of cultured rainbow trout (Salmo gairdneri f. irideus), Amago (Oncorhynchus rhodurus f. macrostomus), Kokanee salmon (O. nerka f. adonis) and Iwana (Salvelinuspluvius) against three fish-pathogenic bacteria, Aeromonas salmonicida, Vibrio anguillarum, and Pseudomonas anguilliseptica were studied. The fishes were injected intramuscularly with each pathogen and kept at 135°C. The results obtained are as follows: 1) All the species of trout tested were sensitive to A. salmonicida, and Iwana seemed to be the most sensitive of them. 2)V. anguillarum exhibited pathogenicity for the four fish species. Of them Iwana had the highest sensitivity to the bacterium, and rainbow trout had somewhat lower sensitivity than the remaining two species. 3) None of the trout tested was sensitive to Ps. anguilliseptica.
The direct fluorescent antibody technique was applied to a survey of “Pseudotuberculosis” in cultured yellowtail (Seriola quinqueradiata) in Miyazaki Prefecture. At the incipient stage of this infection, the characteristic lesions could not be found in spleens and/or kidneys of yellowtail macroscopically, although the causative bacteria could be detected in these specimens with the fluorescent antibody technique just as in conventional cultural procedure. It was established that the fluorescent antibody technique could be utilized as a diagnostic procedure of subclinical infection of “Pseudotuberculosis” in yellowtail.
Eggs of Bothriocephalus opsariichthydis YAMAGUTI, 1934 were collected by dipping its gravid proglottides into sterilized water. The eggs were ovoid and measured 42-57×33-40μ. They had thick, slightly adhesive shells of about 1μ thick and contained no oncospheres when expelled from uterus. The coracidia were hatched out mostly between 2 to 5 days at 25deg;C, but not at 37deg;C and 15deg;C. Light was not needed for hatching. The coracidia were spherical and had cilia of 12-20μ long on the surface. They measured 18-24×15-23μjust after hatching and were enlarged to 76×73μto 107×96μafter 6 hours. Since the embryos die rapidly at 2-7deg;C, it is assumed that the eggs are unable to survive the winter in the pond.
It was confirmed by experiment that the eggs of Bothriocephalus opsariichthydis YAMAGUTI, 1934 collected artificially were killed rapidly by drying, freezing, and ultraviolet rays. Eleven chemicals were tested for ovicidal effect. Among them two chlorine compounds were found to be effective; that is, 3.1 ppm of sodium dichloroisocyanurate and 9.0 ppm of higher bleaching powder killed all eggs.
A. crassa deposits its thin-membraned eggs already containing fully formed sheathed-larvae in the lumen of the swimbladder. Occasionally eggs are released in large numbers by rupture of the body wall and uterus. The sheathed-larvae hatched out in the lumen of the swimbladder are passed through the pneumatic duct and digestive tract into the water, where they can survive for some months without shedding the sheath. Part of the larvae invade the wall tissues of the swimbladder, though their fate is not known. The larvae eaten by the copepod Eucyclops serrulatus pierce the intestinal wall and penetrate the body cavity within a few days at the latest, in which they start to grow immediately. The larvae moved to the body cavity have no sheath. On the contrary the larvae eaten by Sinodiaptomus chaffanjoni can penetrate the body cavity, but no copepod habouring the larvae in its body cavity can be found 24 hours after infection. This fact is possibly due to death of the infected copepods.
Histopathological studies made on 38 diseased eels collected from eel-ponds revealed that Edward siella tarda infections could be classified into two forms, nephric and hepatic. The present paper deals with studies on the nephric form. The primary histologic lesion observed was the appearance, in the sinusoids of the hematopoietictissue of the kidney, of small masses of neutrophils containing those phagocytizing bacteria and those dying and collapsing from intracellular bacterial multiplication. Phagocytotic activity of the reticuloendothelial cells lining the sinusoids was also observed. Small abscesses involving the hematopoietictissue and nephrons were abundantly found in the kidney of diseased fishes in the early stages. These abscesses were thought to develop from the above-mentioned primary foci. The abscesses were characterized by a predominance of juvenile neutrophils. Bacterial multiplication and spreading to the surrounding tissues were found to follow liquefaction of enlarged abscesses. In the kidneys where enlarged abscesses involved large blood-vessels pus emboli and metastatic abscesses were observed in the various parts of the hematopoietic tissue. Peripheral abscesses were found to develop into ulcers. In the stages of the generalized infection various pathological changes and metastatic lesions in particular were observed in the other organs, that is, a serous-exudative and tissues-liqefactive reaction, a degenerative-necrotic reaction, and abscesses formation in the spleen;parenchymal fatty change in the liver;pyemic embolisms in the liver, epicardium, stomach and gills. Suppurative lesions which could develop into perforation were commonly found in the region of the body musculature adjacent to large ulcers of the kidney. Thus in far-advance stages the disease condition was characterized by pyemia. On the base of these findings the name of suppurative interstitial nephritis was suggested for the nephric form of the disease.