IJA Volume 59, Issue 3, 2007
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ItemDiet-Influenced Performance of Juvenile Common Carp (Cyprinus carpio L.) after Experimental Aeromonas Infection(Israeli Journal of Aquaculture - BAMIGDEH, 2007)The effects of two diets, SGP 493 (Aller Aqua, Denmark; SGP) and chironomid larvae (Katrinex, Poland; CHI), on juvenile carp survival and hematological values after subcutaneous infection with Aeromonas veronii bt. sobria (strain K144) were studied. All infected fish developed skin ulcers and both groups developed anemia, i.e., a severe reduction in hemoglobin content with- out a decrease in red blood cell count and a minor decrease in hematocrit. There were higher levels of hematocrit, hemoglobin, and mean cell hemoglobin in the CHI group at the beginning of the infection, together with a slightly higher erythropoietic potential. At the end of the experi- ment, partial recovery of hemoglobin levels took place. The SGP diet induced considerable leukocytosis in healthy fish, which did not enhance their resistance to the infection. Leukopenia, lymphopenia, and reduced phagocyte activity took place in all infected fish. Survival 15 days after injection was 50% in SGP and 63% in CHI, suggesting that fish fed natural food were slight- ly less susceptible to Aeromonas-induced anemia even though feeding natural food or SGP did not significantly affect the performance of infected fish.
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ItemThe Fatty Acid Profile of the Marine Cephalopod Loligo vulgaris(Israeli Journal of Aquaculture - BAMIGDEH, 2007)Squids and their by-products are widely used as pre-spawning feeds in marine fish hatcheries. Therefore, we studied the fatty acid composition of mantle tissue, arms, fins, and gonads of the marine cephalopod, Loligo vulgaris, from a broodstock nutrition point of view. Docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids represented nearly half (>45%) of the total fatty acids, with DHA the most abundant fatty acid in all investigated tissues. The fatty acid profile of the gonads differed significantly from those of the mantle, arms, and fins; EPA was present in a sig- nificantly higher proportion (20%), perhaps indicating its important role in reproduction. Results indicate that Loligo vulgaris and its by-products can be an important nutritional component of broodstock feeds, serving as a major source of DHA and EPA.
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ItemOccurrence and Distribution of Actinomycetes in Marine Environs and their Antagonistic Activity against Bacteria that is Pathogenic to Shrimps(Israeli Journal of Aquaculture - BAMIGDEH, 2007)The mean population density of actinomycetes in water samples from eight stations off Little Andaman Island in India ranged from 0.29 x 103 CFU/ml at station 2 (Naval Area) to 0.45 x 103 CFU/ml at station 4 (Chandra Nallah). Density in sediment samples ranged from 1.21 x 103 CFU/g at station 2 (Naval area) to 3.29 x 103 CFU/g at station 6 (Buttler Bay). Forty-one strains were isolated and tested for their antagonistic activity against Vibrio alginolytics, V. harveyi, and V. parahaemolyticus, bacteria that are highly pathogenic to shrimps. Over 60% of the strains (26) exhibited varying degrees of antagonistic activity. Among them, six showed good activity and were tentatively identified as Streptomyces xantholiticus, S. aureofasciclus, S. galtieri, S. vastus, S. galbus, and S. rimosus. Results suggest that actinomycetes from the marine environment can be used as bio-control agents in shrimp culture systems to control diseases caused by bacteri- al pathogens.
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ItemPituitary Collection from Gibel Carp Carassius gibelio (Bloch 1782) in Lake Pamvotis (Greece): Prospects for Use in Carp Reproduction(Israeli Journal of Aquaculture - BAMIGDEH, 2007)Gibel carp (Carassius gibelio Bloch, 1782) is regarded as a pest species in most aquatic ecosys- tems where it occurs and eradication methods have not been very promising. However, because of the close taxonomical proximity between gibel carp and cultured cyprinids, the pituitary of gibel carps could be exploited for hormonal induction of artificial propagation in aquaculture. Thirty-two mature female gibel carps were electrofished in Lake Pamvotis (northwest Greece) in March 2005 and their pituitaries were collected and processed. The carp luteinizing hormone (cLH) levels in 20 pituitaries were assayed and found to correlate with total body weight, total length, dry pituitary weight, and gonadosomatic index. The cLH levels were in the same range as cLH levels in pituitaries of common carp (Cyprinus carpio Linnaeus, 1758) used in Israeli hatcheries for artificial propagation. Hence, it may be possible to use gibel carp pituitaries for hormonal induction in cyprinids, with total weight of the gibel carp as a field criterion for select- ing pituitary donors.
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ItemImmunostimulatory Effects of a Yeast (Saccharomyces cerevisiae) Cell Wall Feed Supplement on Rohu (Labeo rohita), an Indian Major Carp(Israeli Journal of Aquaculture - BAMIGDEH, 2007)The immunostimulatory role of an orally administered yeast cell wall preparation from Saccharomyces cerevisiae (NutrifermTM) was assessed in the Indian major carp, rohu (Labeo rohita). Fish were fed a diet containing the preparation for 15 days and then returned to the con- trol diet for 20 days. Non-specific immunity was assessed at the end of the experimental feed- ing period (day 0) and on days 10 and 20. In vitro oxidative radical production, phagocytosis of leukocytes, nitrite production, and proliferation of lymphocytes were determined. All four para- meters remained stable in control fish but, in fish fed the supplemented diet, reached a peak on day 10 and remained higher than in the control until day 20, indicating that ingestion of the diet containing the yeast cell wall preparation for 15 days had significant immunostimulatory effects.
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ItemEffects of n-3 PUFA Levels in Live Foods on Albinism, Growth, Survival, and Salinity Tolerance of Flounder (Paralichthys olivaceus) Larvae in Large-Scale Artificial Rearing(Israeli Journal of Aquaculture - BAMIGDEH, 2007)The effects of feeding enriched rotifers and Artemia nauplii on albinism in flounder (Paralichthys olivaceus) larvae raised in a large-scale artificial system were investigated. Larvae were first fed an S-type rotifer (Brachionus angularis) enriched with Nannochloropsis oculata for 11-12 days, which raised the n-3 polyunsaturated fatty acids (PUFA) content in the rotifer from 5.36% to 17.63% of the total fatty acids. Next, the larvae were fed one of three strains of Artemia enriched with microcapsule (50DE), vitamin A (9000 IU/l), and vitamin D (2000 IU/l) for 35 days, which raised the n-3 PUFA contents in the Artemia to 38.62%, 36.53%, and 33.86% of the total fatty acids, respectively. Among the larvae fed the enriched feeds, no more than 3‰ were albino, much fewer than in the control groups fed non-enriched foods (p<0.01). In addition, n-3 PUFA contents in the muscles, growth and survival rates, and salinity tolerance were greater in founder fed the enriched foods. Artemia nauplii from Qixiangcuo (Tibet, China), enriched to 38.62% of total fatty acids, was superior in preventing albinism than the strains from Pikou or Yingkou (Liaoning, China).
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ItemAntibacterial Activity of Oxytetracycline Hydrochloride, Environmentally-Protected or Not, after Feed-Pelleting and during Decay-Dispersion in Saline Water(Israeli Journal of Aquaculture - BAMIGDEH, 2007)Bivalent and trivalent cations quelate oxytetracyline (OTC), rendering it microbiologically inac- tive. Yet shrimp diseases are often treated with OTC in pelleted feeds. Attempts have been made to chemically protect the OTC concentration in shrimp feeds against degradation in brack- ish water and due to temperature. The antibacterial activity of two such environmentally-protect- ed OTC preparations (premixes A and B) and one unprotected OTC premix (C) were tested (a) before and after pelleting the OTC premixes with the powdered feed ingredients and (b) during decay-dispersion of the OTC-medicated feed in brackish water. In all three treatments, the OTC concentration dropped by approximately half after pelleting (p<0.001). When pellets were placed in tanks containing water of 23-25°C, pH 7.6-7.8, and marine salt (40 g/l), a second order expo- nential decay of antibacterial activity followed, reaching 50% in 30 min. At 150 min, loss reached 80% in group A, 85% in group B, and 98% in group C, suggesting that only environmentally-pro- tected OTC may, in some cases, reach the minimal therapeutic concentration necessary to treat Vibrio spp. diseases.
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ItemIsolation of Putative Probionts from the Intestines of Indian Major Carps(Israeli Journal of Aquaculture - BAMIGDEH, 2007)Probiotic strains were isolated from the intestines of 28 Indian major carps (Labeo rohita, Catla catla, Cirrhinus mrigala) cultured in sewage-fed ponds. Intestinal microflora were isolated, count- ed, and identified, and their in vitro antibacterial properties were determined. The double layer method revealed that four strains (SG1, SG2, SG3, SG4) elicited antagonism against the pathogen Pseudomonas fluorescens. Using cross streak and parallel streak methods, SG4 max- imally inhibited the fish pathogens Pseudomonas fluorescens, Aeromonas hydrophila, and Edwardsiella tarda. Therefore, SG4 was chosen for further study as a probiont. SG4 was non- pathogenic to C. mrigala fingerlings, and adhered well to stainless steel, high density polyethyl- ene, and glass plate substrates. Biochemical tests showed that SG4 was endospore-forming, aer- obic, motile, rod-shaped Bacillus subtilis. However, since in vitro experiments can only give an indication of in vivo success, future research should include large-scale in vivo experiments.