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Tenacibaculum maritimum (formerly Cytophaga marina and Flexibacter marinus) is an opportunistic bacterial pathogen that causes a disease called 'flexibacteriosis' in marine fish. Other names that have been used for flexibacteriosis are 'gliding bacterial disease', 'eroded mouth syndrome' and 'black patch necrosis'. The disease is mainly characterised by haemorrhagic skin lesions and this condition is also associated with fin and gill disease. In a few cases, systemic forms have also been reported. Initially, T maritimum was isolated from marine fish cultured in Japan in 1979 (Hikida and others 1979). The first report in Europe was published in 1982, in Dover sole (Solea solea) (Campbell and Buswell 1982). Flexibacteriosis is currently widely spread in Europe, the USA and Japan, affecting many marine fish species (Vatsos 2007) Based on phenotypic and biochemical characteristics, T maritimum is generally considered as a homogeneous taxon. Methods for isolation and identification of the pathogen include the following: observation of accumulations of long rods in wet mounts or gram-stained preparations obtained from gills or skin lesions; isolation in various culture media, especially Anacker and Ordal, Marine Agar, Flexibacter maritimus medium (FMM; Pazos and others 1996); and PCR (Toyama and others 1996, Avendaño-Herrera and others 2004). Greece is the main producer of sea bream (Sparus aurata) and sea bass (Dicentrachus labrax) in the Mediterranean area. Flexibacteriosis is considered as one of the main bacterial diseases in these two species, especially when stressful conditions occur (Toranzo and others 2005). In the present study, several strains of T maritimum were collected from various marine farming sites in Greece, in order to investigate whether the strains present in Greece share a similar biochemical profile. This information is currently not available and is critical in many epidemiological studies. Eleven strains of T maritimum were collected from many areas of Greece (Table 1). These strains were isolated from various field samples, which were sent to the

Probiotics for freshwater fish farming can be administered as single or multiple mixtures. The expected benefits of probiotics include disease prophylaxis, improved growth, and feed conversion parameters, such as the feed conversion rate (FCR) and specific growth rate (SGR). In the current work, we review the impact of probiotics on freshwater finfish aquaculture. Data were gathered from articles published during the last decade that examined the effects of probiotics on fish growth, FCR, and water quality in freshwater fishponds/tanks. While the expected benefits of probiotics are significant, the reviewed data indicate a range in the level of effects, with an average reduction in ammonia of 50.7%, SGR increase of 17.1%, and FCR decrease of 10.7%. Despite the variability in the reported benefits, probiotics appear to offer a practical solution for sustainable freshwater aquaculture. Disease prophylaxis with probiotics can reduce the need for antibiotics and maintain gut health and feed conversion. Considering that fish feed and waste are two significant parameters of the aquaculture ecological footprint, it can be argued that probiotics can contribute to reducing the environmental impact of aquaculture. In this direction, it would be beneficial if more researchers incorporated water quality parameters in future aquaculture research and protocols to minimize aquaculture’s environmental impact.

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The parasitic fauna of the small-spotted catshark, Scyliorhinus canicula in the north-eastern Aegean Sea was investigated. Twenty-one out of the 52 (prevalence 40.4%) specimens collected were found infected with parasites; an arthropod and two nematode genera. Seven specimens (prevalence 13.5%) were infected by a Neoalbionella sp. copepod. Ten and 14 specimens were infected by the nematodes Proleptus obtusus (prevalence 19.2%) and Anisakis sp. (prevalence 26.9%), respectively. Female S. canicula specimens were significantly more heavily infected during autumn and when the whole sampling period is considered. Nematode infection was significantly related to season, becoming progressively heavier from spring to autumn. No correlation was found between TL of specimens and number of parasites for males or females, irrespective of gender. The present study provided a first record of Neoalbionella sp., P. obtusus and Anisakis sp. infections of S. canicula in the north-eastern Mediterranean. The lower prevalence of Proleptus obtusus and the higher prevalence of Anisakis sp. infection recorded in this study may be due to prey availability and parasite populations in this locality.