Studies on the probable sources of fungal infection and the control measures in a fish seed farm

The causes of mortality of fry of cultivable fishes in a fish seed farm were investigated. The mortality was due to fungal infection and the pathogen was Saprolegnia sp. The sources of infection were unhygienic breeding hapas, spawnery hapas in the cemented ponds, hatching jars and excess feeding. Application of one kg slaked lime followed by 75g of CuSo sub(4)(l-0.5 p.p.m.) and 150g of KMno sub(4)(2-1 p.p.m.) per each nursery (158m³ water) controlled the pathogen.

Some fungal infestations of dried fishes in Cochin markets

Dried fish constitutes a regular item of trade in India, particularly in the interior parts far away from the sea and rivers. The poor section of the society is the main consumer. The quality of dried fish never receives much attention at any stage of processing (drying) and storage. A good amount of these fish is discarded during drying due to fungal growth to avoid the danger of mycotoxin production. A survey of the dried fish from the Cochin markets had revealed that they do carry fungal infestations and their chances of mycotoxin production cannot be ruled out as the strains of Aspergillus flavus, Aspergillus ochraceus and Fusarium spp. have been isolated.

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.

Evaluation and comparison of ozone, hydrogen peroxide and physical treatment on fungal infection prevention and hatching rate of Iranian sturgeon (Acipenser persicus)

Ozone due to having low half-life and devoid of environmental harmful effects is recognized as one of the most effective disinfectant and fungicide in aquaculture. The objective of this study is to consider the effects of periodicay ozonation, hydrogen peroxide treatment, and physical treatment capability in hatching rate enhancement. Three concentrations of 0.05, 0.1 and 0.15 ppm ozone (10 min) and peroxide hydrogen with dose of 500 and 1000 ppm in two procedures accompanied with physical treatment and without physical treatment were examined on hatching rate. In the first year, Egg ozonation (0.1 ppm) with physical treatment have been resulted the greatest hatching rate (81.4%). In the second year, egg treatment with 1000 ppm hydrogen peroxide with physical treatment have been showed the greatest hatching rate (78%). Average hatching rate for the blank control treatment (without disinfectin and physical treatment) was 32.7%. From the economic viewpoint, 0.05 ppm ozone with physical treatment, due to considerable minimizing at consumption energy and ozonation system retention costs, indicated as the best treatment than other ozone treatments for fungal control. Very low correlation (r=-0.14) have been observed between hatchery water temperature and fungal infection percentage in control treatment.

Containing the diseases in aquaculture

A brief discussion is presented on epizootics and their containment in the aquaculture industry, in the form of a question-and-answer interview. Particular reference is made to activities carried out by the OIE (Office International des Epizooties), whose main activities include the provision of guidelines and standards for health protection applicable to international trade in live animals and their products. It has devised an early warning system to apprise its member countries of the occurence of disease outbreaks that would have serious repercussions on public health or the economics of animal products. URI

Parasitic fish diseases and their impact on potential fish production in East Africa

Protein deficient diets are a standard way of life in many parts of East Africa;this of course tends to result in shorter life expectancy and chronic ill-health. Population increase is sufficiently high to outdistance the economic gains that may be made in various fields. With recurrent shortages of basic commodities not only in East Africa, but in many parts of the world, it is becoming increasingly clear that agricultural production practices must be maximised rapidly in order to meet the world's constantly expanding need for food. Here in East Africa, while our food requirements can be met most of the time, our protein requirements are far from being met. Yields from traditional fishery resources, must therefore be increased. The farming of fish (aquaculture)adds a new dimension to food production in general and high quality protein production in particular, in that it can be incorporated into other agricultural production activities.