Larval nematodes in stomach wall granulomas of smelt Osmerus eperlanus from the German North Sea coast

Occurrence of stomach wall granulomas in European smelt was studled at 6 locations along the German North Sea coast. Identification of larval nematodes inhabiting these granulomas is provided for the first time. Three species, isolated by pepsin-HC1 digestion, are involved: Hysterothylacium cf. cornutum, Cosmocephalus obvelatus and Paracuaria tridentata. 72% of all stomachs examined were affected. The ratio of number of granulomas to number of the 3 larval species free in the mesentery was 1:1.3. Differences in prevalences and intensities were significant among all locations. Granuloma abundance was highest in samples from the Elbe estuary decreasing in the other locations relative to their distance from the Elbe. There was no relationship between the number of larvae encapsulated on the stomach wall and the number of larval P decipjens in the musculature (r = 0.3). Host condition factor could not be related to number of granulomas. Smelt appaears to be an important transmitter of spiruroid nematode larvae to marine birds in this region

Preliminary Evaluation of Jackbean (Canavalia ensiformis L.DC) Seed Meal as a Substitute for Fishmeal in diets for Clarias gariepinus (Burchell, 1822)

Jackbean (Canavalia ensiformis) is an under-utilized legume with crude protein content and amino acid profile that make it a potential ingredient in the tropics as substitute for fish meal in fish diets. This study assesses the potentials of Jackbean seed meal (JBSM) for partial replacement of fish meal in diets of Clarias gariepinus. Fishmeal in control diet was replaced progressively (10%, 20% 40% and 60%) by raw JBSM, 30-and 60-minute boiled JBSM. Test fish in each tank were fed 3% of their biomass twice daily for 56 days. Fish fed control diet had the best performance (Specific growth rate 1.6; Feed conversion ratio 1.88: Protein efficiency ratio 1.74). Specific growth ratio and PER of fish groups fed test diets were inversely related to the dietary levels of JBSM. The same trend applied to protein and fat contents of the fish carcass. Feed conversion ratio however had the reverse trend. Fish fed diets with up to 20% fishmeal substituted by 60 minute boiled JBSM had protein content similar to those fed the control diets (

Can Myxosporean parasites compromise fish and amphibian reproduction?

Research into fish and amphibian reproduction has increased exponentially in recent years owing to the expansion of the aquaculture industry, the need to recover fishery populations, the impact of endocrine disruptors on the aquatic environment and the global decline of amphibian populations. This review focuses on a group of parasites, the Myxozoa, that affect fish and amphibian reproduction. Lists of the myxosporeans that specifically infect gonads are provided. Most of these are parasitic of freshwater hosts, and most amphibian cases are reported from testes. Sex specificity and sex reversal are discussed in relation to gonadal parasitism. The immune response of the fish to the infection is described, and the contribution of the immunoprivilege of gonads to host invasion is emphasized. The pathological effect of these parasites can be significant, especially in aquacultured broodstocks, on some occasions, leading to parasitic castration. Although myxosporean parasites are currently not very frequent in gonads, their impact could increase in the future owing to the transactions in the global market. Their easy release into the aquatic environment with spawning could make their spreading even more feasible. In the absence of commercial drugs or vaccines to treat and prevent these infections, there is an urgent need to develop specific, rapid and reliable diagnostic tools to control and manage animal movements. In addition, much effort is still to be made on deciphering the life cycle of these organisms, their invasion strategies and their immune evasion mechanisms

Diseases and Mortalities of Fishes and Other Animals In the Gulf of Mexico

Most mortality results from natural causes including red tide which is primarily restricted to West Florida and cold-kills that have greater influence in the warmer regions of South Texas and South Florida, but also kill a significant amount of fish and other animals in the northern Gulf. With the exception of red tide and other harmful algal blooms, the health of the Gulf has not been systematically studied. Mexico has only recently started to evaluate the health of its coastlines. Mortalities of marine animals, particularly fishes, in the Gulf caused by natural and anthropogenic events seem to interact with infectious disease agents and noninfectious diseases, but the mortalities are often attributed to the disease agents alone. “Events” that cause mortalities include eutrophication; hypoxia; algal blooms; temperature, salinity, and weather extremes; and chemical and sediment pollution. “Diseases” include those caused by infectious agents, parasites, neoplasms, and developmental abnormalities. Interactions of the effects of diseases and stressful events are considered important but little investigated