Gross clinical signs and haematological changes associated with artifical infection of Edwardsiella tarda in Koi Carp

The occurrence of diseases is a significant setback for successful aquafarming. One of the common fish bacterial disease syndromes, Edwardsiellosis is caused by Edwardsiella tarda, a gram-negative, rod shaped bacterium associated with several diseases of marine and fresh water fish. In this study, an attempt was made to observe and analyze the onset of clinical symptoms and certain haematological parameters in Koi Carp, Cyprinus carpio L., following artificial infection with Edwardsiella tarda. The disease progress was observed and the clinical symptoms were monitored over a period of 15 days following infection. Fish were sampled at three day intervals to analyse the haematological parameters: total erythrocyte counts (RBC), total leucocyte counts (WBC), haemoglobin content and differential leucocyte count. Clinical symptoms observed included: erratic swimming behaviour, loss of appetite, haemorrhages, dropsy and exophthalmia. There was a significant decrease in the total RBC and haemoglobin levels by the 3rd and 6th day post infection, and an increase thereafter. WBC counts were higher in all infected groups in comparison to the control group. A significant increase in the number of neutrophils was found in the infected group up to the 9th day and a decrease thereafter. The lymphocyte number was significantly less up to the 12th day while the monocyte counts were significantly higher up to the 12th day post infection. The results showed that the bacterium, E. tarda, is pathogenic to Koi Carp. The hematological changes and clinical signs in infected fish reported in this paper will be helpful in the identification and the control of this infection.

Effect of dietary inulin as prebiotic on growth, survival and intestinal bacterial density of juvenile great sturgeon (Huso huso)

Use of prebiotics, nondigestible dietary ingredients that beneficially affect the host by selectively stimulating the growth of and/or activating the metabolism of healthpromoting bacteria in the intestinal tract, is a novel concept in aquaculture. An 8-week feeding experiment was conducted to investigate the effects of dietary prebiotic inulin on the growth performance, intestinal bacterial density, body composition and values of blood serum enzymes in the juvenile great sturgeon (Huso huso). Three replicate groups of fish (initially averaging weight 16.14±0.38g) were fed diets containing prebiotic inulin at levels ranging from 1% to 3%. The basal diet was contained 3% cellulose. The results of linear regression showed there was a negative relationship between some performance indices including weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), net protein utilization (NPU), energy retention (ERE), feed efficincy (FE), protein retention (PR) and supplementation level of inulin. At the end of trial, the 1% inulin treatment insignificantly showed an enhaced survival between the treatment groups. Intestinal lactic acid bacteria (LAB) increased in group treated with 1% inulin compare to other groups. No significant difference were observed in body composition and level of serum enzymes (P>0.05). Moreover there was significant correlation between ALT and LDH values (P<0.01). Result obtained in this study shows that the prebiotic inulin didn’t influence the increase of the growth performance of juvenile great sturgeon and it is not appropriate for supplementation in the diet of beluga.

Water budgeting studies on the hatchery and nursery rearing practices for the common carp, Cyprinus carpio (Linnaeus, 1758)

Aquaculture systems are an integral element of rural development and therefore should be environment friendly as well as socially and economically designed. From the economic standpoint, one of the major constraints for the development of sustainable aquaculture includes externalities generated by competition in access to a limited resource. This study was conducted as an investigation into the water requirement for the hatchery and nursery production phases of common carp, Cyprinus carpio (Linnaeus, 1758) at the Maharashtra State Fish Seed Farm at Khopoli in Raigad Dist. of Maharashtra during the winter months from November to February. The water budgeting study involves the quantification of water used in every stage of production in hatchery and nursery systems and aimed at becoming a foundation for the minimization of water during production without affecting the yield; thereby conserving water and upholding the theme of sustainable aquaculture. The total water used in a single operation cycle was estimated to be 11,25,040 L [sic]. Out of the total water consumed, 4.74% water was used in the pre-operational management steps, 4.48% was consumed during breeding, 62.72% was consumed in the hatching phase, 21.50% was used for hatchery rearing and 6.56% was consumed during conditioning. In the nursery ponds, the water gain was primarily the regulated inflow coming through the irrigation channel. The total quantum of water used in the nursery rearing was 31,60,800 L [sic]. The initial filling and regulated inflow formed 42.60% and 57.40% respectively of water gain, while evaporation, seepage and discharge contributed 20.71%, 36.46% and 42.82% respectively to the water loss. The total water expended for the entire operation was 1,21,61,120 L [sic]. Water expense occurred to produce a single spawn in the hatchery system was calculated and found to be 0.56 L while the water expended to produce one fry was calculated as 4.86 L. The study fulfills the hydrological equation described by Winter (1981) and Boyd (1985). It also validates the water budget simulation model that can be used for forecasting water requirements for aquaculture ponds (Nath and Bolte, 1998).

Evaluate the efficiency of hydrogen peroxide and levaemisole hydrochloride in the treatment of Persian sturgeon, Chinese carp eggs and juveniles

During a two years research hydrogen peroxide efficacy evaluated for Persian sturgeon, Chinese carps and common carp eggs. These series of the experiments conducted in various conditions different concentration of hydrogen peroxide include 250, 500, 750, 1,000 1,500 2,000 3,000 and 9,000 PPM used as ten and fifteen minutes baths, compared with Malachite green and natural control . In the next phase effect of Levaemisole hydrochloride as an immunostimulator which applied as 5 mg/I in twenty minutes baths from day sixth after hatch evaluated by daily mortality rate and leukocytes counts. The results shown that according fertilization percent and temperature condition hydrogen peroxide at 1,000 and 1,500 PPM concentrations is a effective antifungal agent during incubation periods of Persian sturgeon and even sometimes increasing hatching rates significantly comparing with natural controls and Malachite green. In Chinese carps although hydrogen peroxide controls water molds but it is not recommended in high temperatures because it make shortened incubation time and mold infections will decrease. Also the results shown 750 PPM concentration of hydrogen peroxide in common carp eggs controls water moulds infections and increase hatching rate significantly comparing with Malachite green and natural control. Daily mortality rates accessing of Persian sturgeon fries show that 20 minutes baths of 5mg/1 levamisole hydrochloride decreases daily mortality rate during yolk sac absorption. Nitrogenous compounds: nitrate and ammonium differ significantly between treated tanks with control. Blood leucocytes concentrations as an immune index was different significantly in treated fishes by levamisole hydrochloride comparing with controls. In Chinese carps because yolks sac absorption time is short there is not necessary to use the levamisole hydrochloride. Although treated larvae were more active than controls. As a result our suggestions is to use hydrogen peroxide in Persian sturgeon and common carp artificial propagation and also suggest the use levamisole hydrochloride for Persian sturgeon beside management method in stress and pollution condition

Growth rates of juvenile Nile perch, Lates niloticus L. in lakes Victoria, Kyoga and Nabugabo

The growth rates of Nile perch, Lates niloticus L. of 20 cm to 40 cm total length were estimated in lakes Victoria and Kyoga in 1991 and 1992 and Nabugabo in 1992 and 1993 by tagging. Fish grew faster in Lake Kyoga (mean growth rate 28.7 ± 1.3 cm S.E. per year, N = 49) than in Lake Victoria (18.9 ± 1.4 cm per year, N = 20) and Lake Nabugabo (19.0 ± 0.7 cm per year, N = 43). There were significant differences in growth rates between the lakes (F2 109 = 24.037, P < 0.001). Growth rates in Lake Kyoga were significantly higher than those of lak'es Victoria and Nabugabo (p < 0.001) but those of lakes Victoria and Nabugabo were not significantly different from each other (p = > 0.05). The faster growth rates in Lake Kyoga were attributed to improvement in food supply due to increases in stocks of haplochromine prey. Growth rates in Lake Kyoga were significantly higher, but those of lakes Victoria and Nabugabo were within the ranges of those reported in several native habitats of Nile perch.