Mortality Of Fingerlings Research Articles

Therapeutic efficacy of enrofloxacin in treatment of Francisella orientalis infections in juvenile Nile tilapia (Oreochromis niloticus L.).

Outbreaks of infections by Francisella orientalis represent one of the main obstacles to Nile tilapia (Oreochromis niloticus L.) farming. It is responsible for acute mortality in fingerlings and juveniles. The main control measure available is oral antibiotic therapy. This study compared the therapeutic efficacy of the antibiotics enrofloxacin and oxytetracycline, the most commonly used antimicrobial, against francisellosis in juvenile Nile tilapia (O. niloticus). Fish were challenged with a virulent isolate of F. orientalis and treated with medicated feed containing one of two doses of oxytetracycline (100 or 300 mg/kg of live weight (LW)) or 10 mg/kg of LW of enrofloxacin. The positive and negative control groups received feed without antibiotics; the negative control group was unchallenged. The results showed that enrofloxacin at a dose of 10 mg/kg of LW is effective against francisellosis in juvenile Nile tilapia (O. niloticus). Treatment with oxytetracycline did not eliminate the pathogen from the infected host, and the surviving fish became carriers. Enrofloxacin was able to cure the fish of infection with F. orientalis. This study suggests that enrofloxacin is a better option for treating francisellosis in Nile tilapia (O. niloticus L.). It controls mortality and avoids the carrier state in the fish, thus reducing the possibility of recurrence in the affected batches.

Pathogenicity of Aspergillus fumigatus in Experimental Infection of Different Developmental Stages of Clarias gariepinus

Aims: This study aimed to investigating the pathogenicity of Aspergillus fumigatus in the experimental infection of Clarias gariepinus fingerlings and juvenile catfish.
 Experimental Procedure: Aspergillus fumigatus used for this study was isolated from the gills and liver of infected juveniles presented for microbial diagnostic examination, cultured on Sabouraud dextrose agar for 3 – 4 days, and identified at the Aquatic Animal and Wildlife Laboratory (AAWL), Department of Veterinary Medicine, University of Ibadan.
 Methodology: One hundred and forty healthy eight-week old Clarias gariepinus fingerlings (average weight of 4g) and 140 healthy sixteen-week old juvenile (average weight of 10g) were purchased from a commercial fish farms in Ibadan. The fingerlings and juveniles were randomly divided into seven groups, each with 20 fish in five litters of water. The fungal suspension containing 3.2 X 106 spores/ml of Aspergillus fumigatus was used for the pathogenicity test. Six groups were infected by immersion in water containing fungal spores at the rates of 2ml/L and 5ml/L for fingerlings and juveniles respectively. The clinical signs, skin lesions and mortality were observed daily for 14 days.
 Results: Aspergillus fumigatus isolated in this study has green spiked conidia; and the size of the conidia is 2.5µm. The conidia have a smooth surface and small spikes covering their surface. Moreover, the mortality rate was significantly (p = 0.40) higher in infected fingerlings (80%) than juveniles (62%) at fourteen days post-infection. The gross lesions observed during experimental infection of fingerlings and juveniles included exophthalmia, atrophied barbel, congested trunk kidney, hyperemia of gill filaments, and skin depigmentation. The histopathological organ changes caused by Aspergillus fumigatus were obvious in the liver and gills. Vacuolar degeneration of hepatocytes and necrosis of some melanomacrophage cells, in addition, severe erosion of the primary and secondary lamellae, were observed in infected juveniles.
 Conclusion: Aspergillus fumigatus causes high mortality in fingerlings and juvenile of African Catfish (Clarias gariepinus).

Economic analysis of tilapia-carp polyculture in a selected area of Bangladesh

Aquaculture is moving on the way of intensification to fulfill the increasing demand of protein as capture fisheries are declining. The study was conducted to identify the socioeconomic characteristics, analyze the tilapia-carp polyculture system, profitability of tilapia-carp polyculture, and credit profile of the stratified randomly selected 50 sample farmers from Sherpur district in Bangladesh. Primary data were collected through field survey using an interview schedule. Some statistical measures like average percentage and ratios were calculated. The findings revealed that 36% of the respondents belonged to the age group of 25-29 years, 68% belong to medium family size (5 to 6 people), 44% respondents’ education level was higher secondary, 44% respondents’ primary occupation was fish farming and 46 % of were belonged to in annual income level of Tk. 150001-200000 ($1770 - $2360). Average fingerlings released in the tilapia-carp polyculture were 24240 per hectare per year. Most of the fingerlings collected from private hatcheries. The annual per hectare production of tilapia and carp were 8028 kg and 11085 kg., respectively. Per hectare per year gross cost, gross margin, gross return and net return were Tk. 1093008 ($12897), Tk. 759447 ($8961), Tk. 1735455 ($20477) and Tk. 642447 ($7580), respectively. The BCR of tilapia-carp polyculture for cash cost was 1.78 and full cost was 1.59. About 20% of the respondents took loan from different sources and they received 84.51% of their applied amount and 84.73 % of the loan money used in productive purposes. Mortality of fingerlings, the high price of the ingredient, low price of fish, high interest rate and non-availability of good quality fingerlings at proper time were identified to be the major problems in conducting pond fish production. Government and other agencies should come forward to provide subsidized feed, technical supports and credit facilities for the tilapia-carp fish farmers to make the enterprise effectively.

Methods for quantifying eggs and oviposition rate of Dawestrema cycloancistrium (Monogenea: Dactylogyridae), monogenean parasite of Arapaima gigas (Teleostei: Osteoglossidae)

Dawestrema cycloancistrium is the main ectoparasite causing mortality in fingerlings of pirarucu (Arapaima gigas) in Amazonian aquaculture. Very little is known about the D. cycloancistrium reproductive index and appropriate methods of collecting eggs for investigation. This study aimed to determine the oviposition rate of D. cycloancistrium. To achieve this aim, two egg quantification methods were tested: the estimative method (ME) and the total counting method (MT). Compared with the MT, the ME overestimated the number of eggs counted, which were 2943.5 ± 2840.6 and 1041.5 ± 533 eggs, and the oviposition rate, which was 80.1 ± 58.7 and 31.4 ± 16.4 eggs/parasite/day, for ME and MT, respectively. These results show that for studies quantifying D. cycloancistrium eggs, the total eggs in the sample must be counted, as the estimates made using subsamples are not representative. Using the MT, the oviposition rate for D. cycloancistrium was determined to be 31.4 ± 16.4 eggs per adult parasite per day. The present study demonstrates the egg production capacity of a monogenean species parasite of A. gigas, providing basic biological data for D. cycloancistrium.

Effect of packing density on selected tissue biochemical parameters of hatchery produced fingerlings of orange spotted grouper Epinephelus coioides (Hamilton, 1822) during transportaion

<p>Effect of different packing densities on water quality parameters, survival and selected tissue biochemical parameters during transportation of hatchery produced fingerlings of orange spotted grouper <em>Epinephelus coioides</em> (Hamilton, 1822) was investigated. Fingerlings (weight 3.0±0.2 g and length 6.0±0.2 cm) were packed in sealed double layered oxygen packed polythene bags (water and oxygen ratio 1:3) at different packing densities of 20, 30, 40 and 50 no. l-1. The packed fishes were transported for 6 h. After transportation, water samples and tissue samples from fishes were collected for further analyses. Levels of tissue glucose and selected metabolic enzymes (lactate dehydrogenase, LDH; aspartate amino transferase, AST and alanine amino transferase, ALT) significantly (p<0.05) increased with increased packing density. Water quality parameters <em>viz.,</em> pH, dissolved oxygen, CO2, alkalinity, total ammonia nitrogen (TAN) and nitrite nitrogen (NO2-N) were also significantly different at higher packing densities (p<0.05). However, levels of all the tissue biochemical parameters tested were in tolerable range and no mortality of fingerlings was recorded at any of the packing densities. Though the tissue enzyme levels were significantly higher and water quality was significantly deteriorated at the highest packing density of 50 no. l-1, it did not lead to mortality of fish. Therefore, it is inferred that this density can be used for short distance transportation of fingerlings of orange spotted grouper.</p>

<b>Effect of simulated acid rain on the survival, mortality, behaviour and morphology of African mud catfish <i>Clarias gariepinus</i> (Burchell, 1822)

This study simulated acidic habitat for different life stages of Clarias gariepinus to know the effect on survival, mortality, morphology and behaviour. The fish were exposed to pHs 3, 4, 5, 6 and 8.01 (control) for 35 days. 100% mortality was recorded for all the life stages in pH 3, and 80, 62 and 36% of mortality of fingerlings, juveniles and adults respectively were recorded in pH 4. In pH 5, 30, 26 and 12% mortalities of fingerlings, juveniles and adults respectively were recorded and at pH 6 mortalities of fingerlings, juveniles and adults were 12, 10 and 4% respectively. Control pH mortalities were 10, 6 and 2% for fingerlings, juveniles and adults respectively. Mortality was due to lack of oxygen uptake, stress and circulatory collapse. All these elicited the behavioural responses and morphological abnormalities like erratic swimming, gasping, dark body colouration and lethargy. The study showed that different life stages of C. gariepinus tolerate different acidic pH waters, with high mortalities of the fingerlings, juveniles and adults in pHs 3, pH 4 is sub-lethal to fingerlings, juveniles and adult, pH 5 sub-lethal to fingerlings and sub-optimal for juveniles, and pH 6 optimal for all life stages.

Ontogeny of the immune system in rock bream Oplegnathus fasciatus

Histogenesis of the immune system and specific activity of superoxide dismutase (SOD) were studied in rock bream Oplegnathus fasciatus from fertilization to 50 days after hatching (DAH). The pronephric tubule primordium developed in the embryo, 14 h 30 min post fertilization. The spleen anlage was observed between the swim bladder and the intestine at 5 DAH, and the thymus was formed as a paired structure under the pharyngeal epithelium above the gill arch at 10 DAH. The order of the immune organs becoming lymphoid was the pronephric kidney (10 DAH), thymus (15 DAH) and spleen (21 DAH). As the embryo developed, the specific activity of SOD gradually increased until hatching, but subsequently SOD activity continuously decreased to a minimum at 14 DAH. After the spleen became lymphoid, the specific activity of SOD was relatively stable. It is suggested that the immaturity of the lymphoid organs and low specific activity of SOD was the cause of the high mortality of fingerlings 12 to 16 DAH.

Toxicity and Behaviour of <i>Clarias Gariepinus</i> (Burchell, 1822) Fingerlings subjected to Piscicidal Plant Extract of Aidon <i>Tetrapleura Tetraptera</i>

The study was carried out to investigate the toxicity of water extract of Tetrapleura tetraptera fruits on catfish (Clarias gariepinus) fingerlings. The experiment was carried out under laboratory conditions for 96 hours with 30 fingerlings treated with each of the six graded concentrations (0g/300ml, 15g/300ml, 30g/300ml 45g/300ml, 60g/300ml and 75g/300ml) of dried fruits of Tetrapleura tetraptera. The study showed that the higher the concentration of the extract the higher the mortality of fingerlings while the toxicity of the extract reduced with time. Fifty percent mortality of the fingerlings was recorded at 24, 20 and 16 hours for 45g/300ml, 60g/300ml and 75g/300ml concentrations of extracts respectively. The result also showed that there were significant differences (P 0.05) in relation to mean mortality of fingerlings. The treated fingerlings were observed to show erratic swimming and loss of balance at high concentrations of extract. It is recommended that more studies be carried out on other parts of Tetrapleura tetraptera and their effect on different fish species.

Survival of silver catfish fingerlings exposed to acute changes of water pH and hardness

Theaim of this study was to examine the survival of fingerlings of silver catfish,Rhamdia quelen, in water with different pH and hardnessvalues. Fingerlings (1.60 ± 0.14 g; 5.67 ± 0.15cm) were randomly assigned to 35 treatments (in triplicate) andmaintained in 44 L polyethylene tanks (10 fingerlings/tank) for 96h. Fingerlings were exposed to seven solutions of varying pH (3.5,3.75, 4.0, 7.0, 9.5, 10.0, and 10.5) and five solutions of varying hardness(30,70, 150, 300, and 600 mg.l−1 CaCO3).Survival was assessed at 12, 24, 48, 72, and 96 h. Fingerlingmortality was 100% after 12 h exposure to pH 3.5 at all hardnesslevels, whereas mortality at pH 3.75, 10.0, and 10.5 decreased with increasinghardness. There was no mortality of fingerlings exposed to pH 4.0, 7.0, and 9.5at all hardness levels. The results allow us to conclude that the hardnesslevels studied do not affect the survival of silver catfish fingerlings exposedto pH 3.5, 4.0, 7.0, and 9.5 for 96 h. However, the increase ofwater hardness improved survival of fingerlings of this species exposed to pH3.75, 10.0, and 10.5.

Culture, Handling, and Feeding Techniques for Black Crappie Fingerlings

Abstract During the summers of 1980 and 1981, we analyzed techniques to produce, handle, and feed fingerling black crappies Pomoxis nigromaculatus. Production of black crappies was extremely variable, ranging from 0 to a maximum of 164,700 fingerlings/hectare. Brood-fish sex ratios near 1.0 and densities of 100–125/hectare resulted in the highest production of fingerlings per hectare and per female. Brush additions to ponds were unnecessary for successful black crappie spawning. Handling mortality of fingerlings in 1980 ranged from 80 to 100% within the first 3 h following harvest. Use of quinaldine (22 mg/L), a mixture of quinaldine (22 mg/L) and salt (0.5%), or sodium bicarbonate (100 mg/L) as handling treatments did not reduce handling mortality in 1981. However, harvesting at night (at approximately 2300 hours) reduced 3-d mortality of fingerlings to 8%. Fingerling black crappies (25–35 mm) were trained to accept a pelleted ration (Biodiet) with 85–95% success. A 7-d training sequence beginning with c...

溪流区に放流したマス稚魚の生残に関する研究-II

1. Estimation of population size was made directly through observation with water-glass in an experimental area settled in a mountain brook. 2. The research period was divided into four periods owing to the occurrence of principles having influence on the errors of observation. 3. The flood was defined newly. 4. With use of errors of observation measured, a deviced procedure of correction of apparent survival or mortality rate was actually applied. 5. Some adjustment were applied tb apparent observed data including the population size of naturally propagated fingerlings of rainbow trout together with that of stocked rainbow trout fingerlings. 6. The change of behavioristic character made a cause to change the method of adjustment. Change of fishing method involved also made a cause to change the method of adjustment. (However, as the fishing method is subordinate to the change of behavioristic character of fingerlings, the actual principle should be taken to be the latter.) 7. Floods caused a large mortality showing the measures of 50.4 to 62% in rainbow trout fingerlings, and 67.9 to 83.7% in brook trout fingerlings at each flood. 8. Floods had scouring effect on mortality, and of decreased fingerlings 75.3 to 95.5% with rainbow trout and 99.0 to 100% with brook trout were estimated to be swept away from the experimental area, though some of them were expected to remain over some downstream area. 9. The intervals of measuring date in survivor survey before and after the occurrence of flood was thought to have some influence on the measure of scouring effect as well as on that of mortality caused by flood. In this case, the dispersion of fingerlings made on the days of usual flow was considered to be the actual agency to reduce the apparent impression of violence of flood, the action of which emerged in mortality of fingerlings and scouring effect.