Natural Suppression of the Aquatic Weed Salvinia molesta D.S. Mitchell, by Two Previously Unreported Fungal Pathogens

Salvinia molesta D. S. Mitchell (Salviniaceae), variously called giant salvinia, water fern or African payal, is a vegetatively reproducing, perennial, free-floating, aquatic weed, native to southeastern Brazil (Waterhouse and Norris 1987). It (hereafter called salvinia) is a very serious weed in most regions outside its native range (Harley and Mitchell 1981) including India. The purpose of this paper is to report on two fungal pathogens that were found to be the cause of a sudden decline in salvinia in Bangalore.(PDF has 4 pages.)

Survey of fungal infestation of some fish species from Tagwai dam, Minna, Niger State

Survey of Fungal infestation of some species of fish in Tagwai Dam Minna was carried out from March to June 2002. Fungi were isolated from the scale/skin, gills and fins. Twenty-one fungi species were identified from 18 species of fish microbial growth was measured by direct cell count using Stuart colony counter. Most of the fungi encountered were of the mould group and infestation occurred among all the species sampled. The infestation was predominantly by Aspergillus species and the scale/skin was most widely affected. The study showed the identified fungi in order of frequency to be as follows. Aspergillius niger. Rrhizopus spp. Mmucor spp Aspergilus flavum. Aspergillus parasitous. Aspergillus fumigatus, Microsporum canis. Penicillum virridicalumand Fusarium spp respectively. Aspergillus niger occurred on all the species of fish sampled. Barrilius spa and Chrysichrhy auratus longifilis had significantly higher (P<0.05) mean fungal load on their fins and gills. There was no significant difference (P>0.05) in the mean fungal load in different parts of the body of other fish species sampled

Fungal and protozoan parasites and their importance in the ecology of the phytoplankton

The presence of fungi on the phytoplankton of Lake Windermere was first noted by the author in 1943. Surveys into the fungal and protozoan parasites of the planktonic algae of the English Lake District and elsewhere were carried out. This article discusses the descriptive studies, epidemics and culture work, which was carried out in connection with these studies.

Strain comparisons in aquaculture species: a manual

When different strains or breeds of a particular species are available, the best choice is seldom immediately obvious for producers. Scientists are also interested in the relative performance of different strains because it provides a basis for recommendations to producers and it often stimulates the conduct of work aimed at unraveling the underlying biological mechanisms involved in the expression of such differences. Hence, strain or breed comparisons of some sort are frequently conducted. This manual is designed to provide general guidelines for the design of strain comparison trials in aquaculture species. Example analyzes are provided using SAS and SPSS. The manual is intended to serve a wide range of readers from developing countries with limited access to information. The users, however, are expected to have a basic knowledge of quantitative genetics and experience in statistical methods and data analysis as well as familiarity with computer software. The manual mainly focuses on the practical aspects of design and data analysis, and interpretation of results.

Comparative studies on growth of fry of GIFT and Existing strain of Nile tilapia (Oreochromis niloticus L.)

Comparative study on growth of fry in nursery system of Genetically Improved Farmed Tilapia (GIFT) and Existing strain of Nile tilapia (Oreochromis niloticus) was performed. The trials were conducted in a series of hapa for two months. The initial mean weight of GIFT and Existing strains of tilapia were 1.03 and 1.12g, respectively and the stocking density for both the strains was maintained at 150/m³. Fishes were fed with supplementary feed 31.29% of protein level. After two months the final cumulative mean weight of GIFT and Existing strain were observed to be 8.38 and 5.51g, respectively. The net gain for weight of GIFT and existing strain were estimated to be 666% and 368% and the mean survival were 95.75% and 81.25%, respectively. The GIFT strain showed significantly (P<0.05) higher net gain in growth in weight and also higher (P<0.01) survival than that of existing strain.

Breeding biology and monosex male seed production of Genetically Improved Farmed Tilapia (GIFT) strain of Oreochromis niloticus L. in Bangladesh

A study on the breeding biology of the GIFT strain of Nile tilapia, Oreochromis niloticus, was conducted for a period of five months. The sex ratio of the parent individuals was optimized for performance in spawn production, where the best results were obtained with a sex ratio of female to male of 4:1 compared to those of 3:1 and 2:1. The diameter of eggs obtained from the GIFT stock had major and minor axes of 2.19±0.09 and 1.72±0.07 mm, respectively, with no significant differences between the treatments. The average number of eggs produced was 392±22 per female, with fertilization and hatching rates ranging between 94-96% and 85-88%, respectively. No significant variation was observed between the treatments. Breeding frequencies per female in the three treatment groups ranged between 10-40 days and the highest value was obtained at a female to male sex ratio of 4: l. In an other experiment, l7 aMethyltestosterone (MT) was applied orally to the fry at their first feeding stage with treatments- 1, 2, 3 and 4 at the dosage of 100, 80, 60 and 40 mg/kg feed respectively, for the period of 28 days. The mean percentage of males obtained in treatments, 1, 2, 3 and 4 were 98, 97, 95 and 68, respectively. Treatments-1, 2 and 3 did not differ significantly (P>0.05) from each other but treatment 4 showed significant variation (P<0.05) from other treatments. The results showed that MT-100, 80 and 60 mg/kg feed administered for 28 days produced close to cent percent male population of the GIFT strains in aquaria.

Growth performance, recovery rate and fish yield of GIFT strain at various water depths under rice-fish culture systems

Effect of water depth on recovery rate, growth performance and fish yield of GIFT in the rice-fish production systems was studies in experimental plots of 123 m2 with a pond refuge of I meter deep which covered 10% of the total land area. Mortality rate of fish was very low ranging from 0.81-1.63%. However, at harvest, recovery rate ranged from 76.69-82.93% with the highest recovery at 11-15 em of water depth. Significantly the highest absolute growth (99.97) and specific growth rate (2.42%) were found at 21-25 cm water depth. The same treatment also produced significantly higher fish yield (909.76 kg/ha) although statistically similar to the fish yield (862.60 kg/ha) obtained at ll-15 em of water depth. Results also suggested that higher water depth can produce bigger fish but no significant effects of water depth was found on fish yield in the treatments 11-15 cm and 21-25 cm water depths of this experiment.

Establishment of satellite nucleus of genetically improved farmed tilapia (GIFT strain) in Bangladesh

The aim of this study was to evaluate growth performance of the GIFT (Genetically Improved Farmed Tilapia) strain after one generation of selection for increased body weight at Bangladesh Fisheries Research Institute. Founder stock comprised of 30 families having 300 individuals of the GIFT strain were introduced from Malaysia through \X!orldFish Center in March 2005. The founder stock was reared in 100 m2 hapa for three months and then individually tagged using Passive Integrated Transponder (PIT) at the weight between 30 and 40 g. After tagging, all the fish were communally grown out in pond until harvest. Breeding value for body weight was estimated using SAS and ASREML ranging from 4.17 to 9.70 g for males and 4.24 to 9.36 g for females. The best 40 females and 40 males from the founder stock were then selected to produce progeny of the first generation (F-1). From each family 25 female and 25 male fingerlings were sampled and tagged using PIT. A total of 2,000 tagged fish from 40 families were stocked in a pond (1000 m2) for a continuation of the selection program. In addition, surplus fish after tagging were also reared together with progeny of the founder stock in cistern ecology for growth evaluation. The mean weight of the F-1 generation of GIFT fish was 7.2% greater than that of the founder population (non selected population).

Removal of fungus and prevention of fungal reinfestation in stored dry salted fish

A simple and effective method is described for converting dry fish products infested with fungus and red halophilic bacteria to acceptable ones. Washing, drying and then smearing with a mixture of 3% sodium propionate in dry, refined salt in a ratio of 1 part mixture: 10 parts dry fish resulted in the fish having a shelf life of 5 months.

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.

Studies on the fungal diseases in crustaceans. I. Lagenidum scyllae sp. nov. isolated from cultivated ova and larvae of the mangrove crab (Scylla serrata)

Lagenidium scyllae , a marine mastigomycete from the ova and larvae of the mangrove crab, is described and illustrated as new. The fungus grew at a temperature range of 16-42 C, with an optimum at 22.5-31.8 C. It grew well in peptone-yeast-glucose (PYG) broth containing 2-3% NaCl. In PYG-sea water medium, it grew at a pH range of 5-11.

Some observations on the growth and cyst production characteristics of the brine shrimp Artemia sp. (Gujarat strain) in pond culture and its potential for import substitution

Experimental culture of the brine shrimp Artemia sp. (Gujarat strain) and production of cyst is discussed. The qualitative and quantitative aspects of the cyst and its economic potential for import substitution are highlighted.

Temperature effects on pathogenicity of selected Edwardsiella tarda strain to Japanese eel, Anguilla japonica

Temperature effect on the pathogenicity of selected Edwardsiella tarda V-1 strain to Japanese eel, Anguilla japonica was investigated. To evaluate the effects of both pathogen incubation temperature and fish cultivation temperature on pathogen pathogenicity a two-factor design was conducted. E. tarda was incubated at 15, 20, 25, 30 and 37±1°C, and the fish (mean weight: 100g) were reared at 15, 20, 25 and 28±1°C respectively. The fish reared at different temperatures were infected with the E. tarda incubated at different temperatures. The results of a 4-day LD50 test showed that temperature significantly affected the pathogenicity of E. tarda (p<0.01) and the interaction between the two factors was also significant (p<0.01). For fish reared at 20°C the pathogenicity of E. tarda was the highest at 30°C of pathogen incubation. When the fish rearing temperature was raised to 25 and 28°C, the pathogenicity of E. tarda incubated at all temperatures increased. Isolation testing demonstrated results similar to those of LD50. The selected isolate was virulent to eel, but pathogenicity varied with temperature.