Comparison of Vibrio spp. populations found in seawater, in exhibition aquaria, in fish intestine and in fish feed.

AIMS: Vibrio populations in the seawater supply and the water of seven exhibition aquaria that simulate various Mediterranean and tropical ecosystems were compared. The similarity of Vibrio populations in the intestine of various fish species, feed and water was examined. Resistance to the antibiotics used in fish health management was analysed for the dominant Vibrio isolates. METHODS AND RESULTS: Samples were collected for 1 year from seven exhibition tanks reproducing different ecosystems. The diversity and population similarity among vibrios were determined using a miniaturized biochemical phenotyping method. Similar Vibrio populations were found in the water supply and in the water of the Mediterranean ecosystems. However, different Vibrio populations were found in the water of tanks with tropical ecosystems. Vibrio populations in the water seemed to have a greater effect on the composition of intestinal Vibrio populations than those in feed. No resistance to antibiotics was observed, indicating their appropriate use for health management. CONCLUSIONS: Water characteristics have a greater impact on the composition of Vibrio populations in aquaria and fish intestinal microbiota than bacteria in feed. SIGNIFICANCE AND IMPACT OF THE STUDY: The microbiological monitoring water could provide valuable information for managing the health of exhibition aquaria.

Diversity of Vibrio spp. populations in several exhibition aquaria with a shared water supply.

AIMS: Abiotic factors may influence the settlement of bacterial populations in similar marine environments. Exhibition aquaria are a model for the study of the settlement of bacteria in different environment. Vibrio populations in the seawater reservoir, the Mediterranean tank and the Tropical tank from an exhibition aquarium on the western coast of the Mediterranean were compared and the effect of abiotic factors on the structure of these populations was considered. METHODS AND RESULTS: High diversity indexes and similar Vibrio populations were found in the water of the reservoir and of the Mediterranean tank, whereas a lower diversity and different main populations were found in the water of the Tropical tank. The antibiotic resistance profiles of the most representative strains, presented a number of differences depending on the origin of the sample. CONCLUSION: Abiotic conditions, mainly temperature, may determine the structure and composition of Vibrio populations in exhibition aquaria. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacterial monitoring of water could be useful for health management of aquatic environments.

Myxidium leei (Myxozoa) infections in aquarium-reared Mediterranean fish species.

An episode of parasitic enteritis causing trickling mortalities at an exhibition aquarium reproducing Mediterranean ecosystems was found to be caused by the myxozoan parasite Myxidium leei Diamant, Lom & Dykova 1994. The myxozoan was recorded in 25 different fish species belonging to 16 Genera, 10 Families and 4 Orders. It was mainly detected in the intestine of affected fish, and was responsible for severe chronic enteritis. The parasite was probably introduced into the facilities with infected wild fish, and transmitted directly from fish to fish by cohabitation, transfer of infected material and necrophagia. Fish belonging to the Families Labridae and Blenniidae appeared as most susceptible, and the incidence of infections in members of the Sparidae was low. This study significantly widens the host spectrum for this virulent parasite and now includes many ubiquitous coastal Mediterranean species. Wild fish may have a significant role in the transmission of myxidiosis of cultured sparid fish.