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1.
Atlantic salmon, S almo salar L., were exposed to different concentrations of Paramoeba sp. The lowest concentration which induced amoebic gill disease (AGD) was 230 Paramoeba sp. L–1 and the severity of infection increased with increasing concentration. The concentration of Paramoeba sp. positively correlated with the number of gill lesions ( R 2 > 0.7). This study provides evidence that Paramoeba sp. is the causative agent of AGD and describes an experimental model that enables the severity of the induced disease to be controlled. 相似文献
2.
Parasitic infections caused by Tetrahymena sp. constitute a serious problem in guppies, Poecilia reticulata. Tetrahymena was isolated from skin lesions of naturally infected guppies in a commercial aquaculture farm, cultured in vitro and used in subsequent experimental infections. In addition to guppies, angelfish, Pterophyllum scalare, platyfish, Xiphophorus maculates, and neontetra, Paracheirodon innesi, were susceptible, whereas tilapia (Oreochromis niloticus xO. aureus) was resistant. The ciliate had a high affinity for dead fish. Skin abrasion did not affect the infection, but fish with gas bubble disease exhibited a significantly higher infection than non-affected fish. Infection was significantly higher when fish were exposed to high levels of ammonia, high organic load and low water temperatures. Under shipment conditions, infection was significantly elevated. Full recovery was achieved at a low fish density. Results suggest that poor environmental and physiological conditions enhance infection with Tetrahymena sp. 相似文献
3.
Anurag Dagar Dina Zilberg Zvi Cohen Sammy Boussiba & Inna Khozin-Goldberg 《Aquaculture Research》2010,41(2):267-277
Two trials were conducted to determine the effects of dietary enrichments with the microalga Parietochloris incisa , rich in arachidonic acid (ARA), on stress resistance in guppies Poecilia reticulata . The microalga was added to commercial diets as a neutral lipid (NL) extract and its fractions or as broken cells. Experimental diets were applied for a period of 14 days. In trial 1, commercial diets were supplemented with NL (containing 25 mg ARA and 0.11 mg β-carotene g−1 feed), its triacylglycerol (TAG) fraction (containing 25 mg ARA g−1 feed and no β-carotene) and the β-carotene fraction (containing 0.11 mg carotenoid g−1 feed and minute amounts of ARA). Neutral lipid-fed fish demonstrated the highest resistance ( P <0.05) to osmotic stress (32-ppt NaCl), followed by fish fed with diets supplemented with TAG and β-carotene alone, which were more resistant than control ( P <0.05). In trial 2, fish fed diets supplemented with higher levels of broken alga (26.1 mg ARA g−1 feed) were more resistant ( P <0.05) to stress as compared with fish fed lower ARA (16.3 mg g g−1 ) or an unsupplemented control diet. We suggest a dietary supplementation with broken P. incisa cells to enhance stress resistance in guppies before a stressful event. 相似文献
4.
Ji Hyun Kim Sophie Fridman Hamutal Borochov‐Neori Tamar Sinai Dina Zilberg 《Aquaculture Research》2019,50(2):431-438
Garlic (Allium sativum) has been shown to possess antimicrobial properties against a range of disease‐causing agents, including fish parasites. Our study aimed to investigate the potential use of garlic as a treatment against Cryptocaryon irritans infection, using guppies (Poecilia reticulata) as the fish model. Garlic was freeze‐dried, powdered, and used as it is or as an aqueous extract. The content of allicin, its main active ingredient, was 1.25 mg/g in garlic powder and 0.82 mg/ml in the aqueous extract, as determined by HPLC analysis. Aqueous garlic extract fully immobilized C. irritans theronts and protomonts within 20 and 40 min, respectively, following exposure to 5 µl/ml. Treatment trials were performed, in which infected fish were fed with garlic powder‐supplemented feeds (5%, 10%, or 20% supplementation), bathed in garlic aqueous extract (250 or 500 µl/L) and subjected to a combined treatment which included both feeding and bathing. Results revealed that the tested treatments failed to cure the infection, though reduction in infection intensity on the caudal fin, but not on the gills, was evident following dietary supplementation with 20% of powdered garlic in one of the trials. 相似文献
5.
Clownfish, Amphiprion ocellaris Cuvier, produced and grown in an experimental indoor aquaculture facility, presented with lipomatous tumours. A total of 14 affected fish were examined. Based on the total number of fish at the aquaculture facility at the time of outbreak of this pathology, the scope of the incident is estimated to be 1 of 300 fish. The tumours were characterized by the presence of mature adipocytes of variable sizes, lipoblasts and by an invasive behaviour, which affected internal organs, muscle, central nervous system and, in one case, an eye. Detailed macroscopic and histopathological features are presented. The suggested diagnosis is that of a well‐differentiated liposarcoma, a diagnosis so far never applied to fish. The limited outbreak of the neoplasm lasted a few months in 2011 and did not recur. Possible factors leading to this phenomenon, notably the metastasis, are discussed. 相似文献
6.
Atlantic salmon were exposed to amoebic gill disease (AGD) immediately following their acclimatization to sea water (group 1), or following a 2 week period of maintenance in sea water (group 2). Three fish from each group were sampled on days 0, 1, 2, 4, 7, 14 and 28 post-infection. Characteristic gill lesions began to occur between days 2 and 4, and dramatically increased by day 7. The number of gill lesions on fish from group 2 was significantly higher than on fish from group 1 on days 7 and 14 ( P <0.001), but the two groups did not differ in any other parameter. Histologically, Paramoeba sp., the aetiological agent of AGD, could be seen on the gills of fish as soon as 1 day post-exposure, attached to healthy-appearing gills. Gill pathology in the form of hyperplasia and lamellar fusion followed shortly. AGD infection was accompanied by a significant increase in the number of gill mucous cells ( P =0.002). Different methods for the diagnosis of AGD are discussed. 相似文献
7.
M. Wysoki G. Forer E. Dunkelblum Miriam Harel Polina Fraistat Devora Gordon L. Anshelevich M. Kehat M. Kehat L. Anshelevich Devora Gordon Miriam Harel E. Dunkelblum L. Zilberg A. Rubin A. Shani Ada Rafaeli Miriam Altstein Oma Ben-Aziz Irit Schafler I. Seltzer C. Gilon A. Hefetz Tamar Katzav Victoria Soroker Ali R. Harari 《Phytoparasitica》1998,26(2):175-181
8.
Abnormal development of the swimbladder is described in angelfish, Pterophyllum scalare (Lichtenstein 1823), a popular freshwater ornamental fish widely cultured in a range of strains and varieties.
Non-inflated swimbladders in some individuals became apparent when larvae reached an age of 2 weeks. Affected fish were incapable of maintaining their position in the water body and sank to the tank bottom, resting on their flanks. Swimming bouts involved arduous tail movements in an attempt to maintain their position in the water body. Affected fish had slender trunks and partly folded backward dorsal and ventral fins. Histologically, affected fish had a solid cluster of hypertrophic gas gland cells and a hyperplastic rete mirabile instead of a gas-inflated swimbladder. Although it was not determined whether atmospheric air is obligatory for initial inflation of the swimbladder in larvae of this species, the evidence presented suggests that access to the water surface for this purpose in angelfish may not be obligatory. Dilated swimbladders were observed in 1-day-old larvae that were still attached to the hatching stick or had dropped to the tank bottom, with no contact to the water surface. Larvae that had been collected from the water surface displayed similarly dilated swimbladders.
The possible cause of swimbladder non-inflation in angelfish is presently under investigation. Although the aetiology remains unknown, we found some alterations in gene expression that were associated with swimbladder non-inflation. The underlying factors have yet to be determined, although genomic alterations, environmental conditions or induced mutation, which involves both factors, are suspected as contributory factors. 相似文献
9.
Antibacterial and antiparasitic agents and a cysteine protease inhibitor (E‐64) were tested against Tetrahymena infection, a serious problem in guppy production worldwide. Chemicals were tested in vitro by a colorimetric assay for Tetrahymena survival. The most effective were niclosamide, albendazole and chloroquine, with 23%, 35% and 60% survival, respectively, following 2‐h exposure to 100 ppm. Longer incubation periods resulted in greater reductions in survival. Niclosamide was further studied in vivo at different dosages, administered orally to Tetrahymena‐infected guppies. Mortality rates were significantly lower in all treatment groups; in trial I, 30% and 33% mortality in 5 and 40 mg kg?1 niclosamide‐fed fish vs. 59% mortality in controls; in trial II, 35%, 13% and 10% in 50, 100 and 200 mg kg?1 niclosamide‐fed fish vs. 64% in controls. The effect of the cysteine protease inhibitor E64 was tested in tissue culture, by measuring histolytic activity of the parasite (Tet‐NI) on a guppy‐fin cell line, based on cell depletion. Tet‐NI feeding activity was significantly reduced following pretreatment with E‐64 relative to non‐treated Tet‐NI. E‐64‐pretreated Tet‐NI was injected i.p. into guppies: recorded mortality rates were significantly lower (35%) than that in non‐treated Tet‐NI (60%), suggesting inhibition of the parasite’s cysteine protease as a possible therapeutic approach. 相似文献
10.
Failure to inflate the swim bladder is regarded a major obstacle in the rearing of many fish species. We present a study of swim bladder non-inflation (SBN) in angelfish, Pterophyllum scalare. A normal developing primordial swim bladder was first discernable at the end of the first day post-hatch (p.h.) as a cluster of epithelial cells with a central lumen, surrounded by presumably mesenchymal cells. Initial inflation occurred on the fourth day p.h. Prior to inflation the swim bladder epithelium consisted of an outer squamous and inner columnar layer. Cells of the inner layer were filled at their basal region with an amorphous material, which disappeared upon inflation. A pneumatic duct was absent, and larvae presented no need to reach the water surface for inflation, suggesting that angelfish are pure physoclists. A model for the role of the amorphous material in normal initial inflation is proposed. Abnormal swim bladders were apparent from the fourth day p.h., and methylene blue (MB) at a concentration of 5 ppm significantly increased the prevalence of SBN. Histologically, abnormal swim bladders in larvae hatched in 5 ppm MB could not be distinguished from those in fish raised under routine conditions (0.5 ppm MB). We suggest that MB may have a teratogenic effect in angelfish. 相似文献