Health status of a snakehead (Channa punctatus) of two fish markets in Mymensingh, Bangladesh

An experiment was carried out for a period of six months during October 2008 to March 2009 to investigate the health status of a snakehead, Channa punctatus through clinical and histopathological technique. Fish were collected from two fish markets of Mymensingh district. Clinically and histopathologically, it was observed that fishes from both the markets were healthy in October and March but moderately affected in November and February. In the months of December and January, 7.5- 8% of the fishes were affected clinically and showing various clinical signs like, discolouration, deep ulcer, ill health, scale loss and rough skin. Histopathologically, in the month of December and January, major observed pathologies of skin and muscle were necrosis, vacuums, fungal granuloma and loss of dermis. Gills were affected having parasitic cysts, monogenetic trematode, clubbing, loss of primary and secondary gill lamellae, hemorrhage, necrosis and hypertrophy. Vacuoles, pyknosis, hepatic necrosis, hemorrhages and fungal granuloma were observed in liver. Renal pathology included necrosis and pyknosis of kidney tubules, hemorrhages, presence of bacterial colony and vacuoles. From present findings, it was found that, fishes from urban market were more affected with diseases than pre-urban market especially in the months of December and January when compared with other months. From overall observation, C. punctatus were severely affected by epizootic ulcerative syndrome (EUS), dactylogyrosis, protozoan and bacterial diseases during colder months of the year.

Distribution and occurrence of bacterial fish diseases in the different cultural facilities of Lake Kainji area

Fish farming practices in the Lake Kainji Area of Nigeria are categorized under seven main cultural facilities, namely, earthen ponds/reservoirs, indoor/outdoor concrete tanks, plastic tanks, floating cages/hapas, aquaria, sewage and feral conditions. The presence of Bacteria isolates associated with diseased fish conditions varied significantly (P<0.05) with different cultural facilities. The highest bacteria isolates and bacterial disease incidence, 33% and 46% respectively, was associated with diseased fish in the indoor/outdoor concrete tanks. The least incidence of bacteria isolates (3.5%) and blue bacterial disease (3%) was associated with diseased fish in the aquaria and feral conditions. Nine Gram-negative and two Gram-positive bacteria genera were isolated during this investigation. Pseudomonas spp. (23.6%) and Staphylococcus spp. (14.3%), were the predominant Gram-negative and Gram-positive bacteria genera in the different cultural facilities, respectively. This paper highlights the relevance of occurrence and distribution of bacteria isolates associated with diseased fish to bacterial fish diseases under different cultural facilities

The economic impact of diseases and parasitic problems in freshwater fish production

Diseases and parasitic problems could constitute significant economic losses in fish production if not controlled, thus the need to continue monitoring its prevalence. Based on field studies on feral and intensively raised fish at the Kainji Lake Research Institute Nigeria, some diseases and parasitic problems have been identified. These include; helminthiasis; fungal disease; protozoa which include Myxosoma sp., Myxobolus spp., Henneguya sp., Trichodina sp., Ichthopthrius sp. bacterial mainly Aeromonas sp., Pseudomonas sp., mechanical injuries; death due to unknown causes and economic assessment of myxosporidian infection. Suggestion for disease control in fish production are recommended

A review of diseases associated with cage culture systems: diagnosis and control in smale scale fish farming

Fish cage culture is a rapid aquacultural practice of producing fish with more yield compared to traditional pond culture. Several species cultured by this method include Cyprinus carpio, Orechromis niloticus, Sarotherodon galilaeus, Tilapia zilli, Clarias lazera, C. gariepinus, Heterobranchus bidorsalis, Citharinus citharus, Distochodus rostratus and Alestes dentes. However, the culture of fish in cages has some problems that are due to mechanical defects of the cage or diseases due to infection. The mechanical problems which may lead to clogged net, toxicity and easy access by predators depend on defects associated with various types of nets which include fold sieve cloth net, wire net, polypropylene net, nylon, galvanized and welded net. The diseases problems are of two types namely introduced diseases due to parasites. The introduced parasites include Crustaseans, Ergasilus sp. Argulus africana, and Lamprolegna sp, Helminth, Diplostomulum tregnna: Protozoan, Trichodina sp, Myxosoma sp, Myxobolus sp. the second disease problems are inherent diseases aggravated by the very rich nutrient environment in cages for rapid bacterial, saprophytic fungi, and phytoplanktonic bloom resulting in clogging of net, stagnation of water and low biological oxygen demand (BOD). The consequence is fish kill, prevalence of gill rot and dropsy conditions. Recommendations on routine cage hygiene, diagnosis and control procedures to reduce fish mortality are highlighted

The potential for crop rotation in controlling diseases in shrimp culture

The use of antibiotics and other chemicals in controlling shrimp pathogens become ineffective as the strains grow more resistant to these chemicals. Moreover, the bacterial pathogen (Vibrio harveyi) produced biofilm coating that protects it from dying and disinfection procedures that are followed during pond preparation. Biological control is being considered as an alternative means of preventing shrimp disease outbreak. The main principle behind biological control is to enhance the growth of beneficial microorganisms which serve as antagonists or target pathogens. The paper discusses shrimp and tilapia crop rotation as a form of effective biological control, a technique which is already being practiced in Indonesia and the Philippines.

Common fish diseases and parasites affecting wild and farmed tilapia and catfish in central and western Uganda

Intensification of aquaculture production in Uganda is likely to result into disease out-breaks leading to economic losses to commercial fish farms and associated natural aquatic ecosystems. This survey assessed health profiles of selected commercial fish farms and adjacent natural aquatic ecosystemsto identify fish diseases and parasites affecting Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) in aquaculture systems in Uganda. Fish farms encounter disease out-breaks that cause low survival rates (0 - 30%), especially catfish hatcheries. Health management issues are not well understood by fish farmers, with some unable to detect diseased fish. Current control strategies to control aquatic pathogens include use of chemotherapeutants and antibiotics. Bacterial pathogens isolated included Flavobacterium columnare, Aeromonas sp., Edwardsiella sp., Psuedomonus sp., Steptococcus sp., Staphylococcus sp., Proteus sp., and Vibrio sp. A high occurrence of Flavobacterium columnare exists in both asymptomatic and symptomatic fish was observed. Parasites included protozoans (Ichthyopthirius multiphilis, Trichodina sp. and Icthyobodo sp.) and trematodes (Cleidodiscus sp. and Gyrodactylus sp.). Diagnosis and control of diseases and parasites in aquaculture production systems requires adoption of a regional comprehensive biosecurity strategy: the East African (EAC) region unto which this study directly contributes.

Recognizing and managing common fish diseases

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Control of bacterial disease in small scale fresh-water aquaculture: Project R0754. Project completion report December 1998 - May 1999

The work presented here represents an 18-month study to examine the relationship between environmental conditions, bacterial load in the water and bacteria levels in tissue macrophages of a range of clinically healthy freshwater fish species, farmed in a range of culture systems in Thailand and Vietnam. Preliminary assessment was made of the clinical significance of the macrophage bacterial load. The aim of this work was to improve production in fresh-water aquaculture through the control of clinical bacterial disease and subclinical infection, and to identify management practices most effective in promoting fish health. [PDF contains 37 pages]

Bacterial flora of the gut of the African snakehead, Channa obscura (Pisces: Channidae)

A qualitative and quantitative investigation of the bacterial flora of the gut of the African snakehead, Channa obscura was undertaken. The types of bacteria isolated from the different parts of the gut of C. obscura include Pseudomonas, Streptococcus, Citrobacter and Proteus. The coliform (Escherichia coli, Enterobacter) and some other Enterobacteriaceae such as Salmonella were also present. The stomach and intestine were found to have a preponderance of Pseudomonas and Vibrio species. Klebsiella sp. and Bacillus sp. (only in the pyloric caeca) were also isolated. On the whole, the correlation coefficients of the two incubation temperatures showed a high statistical significance. Thus the bacterial load of the gut of C. obscura has been shown as a function of temperature

Watershed monitoring and the TMDL modeling to assess bacterial loading in estuarine environments to improve management

Shellfish bed closures along the North Carolina coast have increased over the years seemingly concurrent with increases in population (Mallin 2000). More and faster flowing storm water has come to mean more bacteria, and fecal indicator bacterial (FIB) standards for shellfish harvesting are often exceeded when no source of contamination is readily apparent (Kator and Rhodes, 1994). Could management reduce bacterial loads if the source of the bacteria where known? Several potentially useful methods for differentiating human versus animal pollution sources have emerged including Ribotyping and Multiple Antibiotic Resistance (MAR) (US EPA, 2005). Total Maximum Daily Load (TMDL) studies on bacterial sources have been conducted for streams in NC mountain and Piedmont areas (U.S. EPA, 1991 and 2005) and are likely to be mandated for coastal waters. TMDL analysis estimates allowable pollutant loads and allocates them to known sources so management actions may be taken to restore water to its intended uses (U.S. EPA, 1991 and 2005). This project sought first to quantify and compare fecal contamination levels for three different types of land use on the coast, and second, to apply MAR and ribotyping techniques and assess their effectiveness for indentifying bacterial sources. Third, results from these studies would be applied to one watershed to develop a case study coastal TMDL. All three watershed study areas are within Carteret County, North Carolina. Jumping Run Creek and Pettiford Creek are within the White Oak River Basin management unit whereas the South River falls within the Neuse River Basin. Jumping Run Creek watershed encompasses approximately 320 ha. Its watershed was a dense, coastal pocosin on sandy, relic dune ridges, but current land uses are primarily medium density residential. Pettiford Creek is in the Croatan National Forest, is 1133 ha. and is basically undeveloped. The third study area is on Open Grounds Farm in the South River watershed. Half of the 630 ha. watershed is under cultivation with most under active water control (flashboard risers). The remaining portion is forested silviculture.(PDF contains 4 pages)

Determination of optimum stocking density of Macrobrachium rosenbergii larvae using multiple feed in a commercial hatchery at Cox’s Bazar, Bangladesh

Experimental stocking density of Macrobrachium rosenbergii in larval rearing was conducted in A.G. Aqua Hatchery, Chakaria, Bangladesh to study the effect of different stocking densities on growth, survival rate and diseases stress under hatchery condition. The research work was conducted using six cemented rectangular tanks having 3m3 capacity (1.5mX2mX1m) each. Stocking density were maintained in three experimental setup as 200, 150 and 100ind/L of the T1, T2 and T3 respectively with one replicate each. The larvae were fed with Artemia nauplii, Custard, Maxima and brine shrimp flakes. Water quality was maintained by exchanging 20-30% (12ppt saline water) daily. During the study period, temperature, pH, DO, salinity, nitrite-nitrogen, ammonia and alkalinity were maintained from 28.5-31.5ºC, 7.5-7.8, 5.8-5.9mg/L, 12-13ppt, 0.14-0.2 mg/L, 0.22-0.3mg/L, and 140-160mg/L respectively. The growth rates of larvae at 11th stage were recorded in terms of body length 0.115, 0.136, and 0.169 mm/day whereas body weight were observed 0.000115, 0.000180, and 0.000240g/day. The survival rate of larvae were found 21.8%, 30.4% and 51.3% in treatments T1, T2 and T3 respectively. PL was obtained as 43, 45, and 51PL/L and days required of 41, 38 and 34 days in stocking density of 200, 150, and 100ind/L respectively. It was found that the minimum of 34 days was required to attain the PL (12th stage) using the stocking density of 100 individuals/L. Cannibalism, Zoothamnium, Exuvia Entrapment Disease (EED), and Bacterial Necrosis (BN) were found to be the threat to the commercial hatchery operation that might responsible for potential larval damages which can be reduced by lowering the stocking densities in larval rearing tank that also increased the survival and growth rate.

On methods of evaluation of bacterial production. [Translation from: Lietuvas TSR Mokslu Akademijos Darbai, C Serija 2(55) 3-9, 1971.]

By now a great deal of work is known concerning the methods of determining the production of bacteria or similar questions; among these the problems of a common terminology is discussed. The article discusses formulae of production of bacterial populations over time.

Bacterial production of nitrate in aquatic systems: progress report. Nitrate-loss processes in raw water

This short interim progress report builds on previous progress reports which have described the quantification of the process both within and between lakes of different degrees of eutrophication. These data indicated that slight changes in methodology, particularly when investigating sediment deposits, could grossly affect the measured activity. The aim of the present research was an attempt to rationalize these differences. If this could be achieved it would enable meaningful interpretation of published data obtained using different methods and therefore enlarge the available database. In addition some observations have been made on the production of nitrite by Grasmere profundal sediment slurries sampled during the circulation period.

Variation in bacterial populations in time and space

Obtaining a reliable estimate of the bacterial population is one of the main problems facing the bacterial ecologist. The author discusses the various methods available and concludes that the observed variability in bacterial populations depends on the sampling interval used.