This study was conducted to investigate the effects of Polyglycerol polyricinoleate, (PGPR; E-476) as a dietary emulsifier supplement with sunflower and linseed oil on zebrafish (Danio rerio) growth performance and feed utilization. The control diet included only fish oil whereas other experimental diets included 6% sunflower oil and linseed oil with and without PGPR at %0.06. A total of 180 zebrafish larvae were used in the experiment. At the end of the experiment, the whole body samples were taken for proximate and fatty acid analysis. The fish were fed diets that contained PGPR, S0%L0% (PGPR), S6%L0% (PGPR) and S0%L6% (PGPR), had higher values (p˂0.05) in final weight (557.1, 521.3 and 622 mg), weight gain (1982.83, 2129.5 and 2779.56%), specific growth rate (2.062, 2.099 and 2.272), digested lipids amount (127.23, 122.65 and 148.52 mg), feed conversion efficiency rate (1.683, 1.893 and 1.725), protein efficiency ratio (1.321, 1.181 and 1.31) and whole body lipid percentage (44.37, 37.9827 and 46.7063 %), respectively. The percentages of fatty acids in fish tissues that fed diet with PGPR diets, S0%L0% (PGPR), S6%L0% (PGPR) and S0%L6% (PGPR), were higher (p˂0.05); ΣSFAs (16.695, 12.732 and 14.672 %), ΣMFAs (17.748, 16.014 and 17.922%), and ΣPUFAs (9.926, 9.235 and 14.111%), respectively, which reflected a positive influence of the emulsifier on zootechnical performance variables. Briefly, the results suggest that dietary use of linseed oil with particularly PGPR appeared to be a better alternative to fish oil.

Responsible aquaculture, the farming of aquatic organisms, is a sustainable strategic sector for land and coastal communities. It significantly contributes to food security and enhancement of economic development; it provides employment opportunities and often contributes to the ecological services provided by the environment. According to the Food and Agriculture Organization of the United Nations (FAO), the contribution of aquaculture to the global food security is widely demonstrated by an astounding industry growth of 7.5% per year since 1970. In 2018, aquaculture reached the all-time highest production of 114.5 million tonnes in live weight with a total farm gate sale value of USD 263.6 billion. This makes aquaculture a key player within the Blue Growth concept and a strong contributor to some of its key Sustainable Development Goals (SDG). This is particularly true in geographical areas where dependence of local economies on fishery products is high, and yet access to sustainable landings is hampered by ecological barriers. One such area is represented by the Black Sea basin. Whilst the Black Sea annual capture fishery production has varied considerably since 1990 and its current landings are significant, growing attention is currently given to boost aquaculture development along the Black Sea bordering countries, with marine aquaculture being considered as an important contributor to the total fisheries production. Nonetheless, aquaculture development in this region is not homogenous and its development has, so far, been limited by environmental, economic, social, and more generally governance issues. This paper, for the first time, attempts to provide a comprehensive fresh outlook of the aquaculture sector in the Black Sea, stressing the importance of regional cooperation as an essential pillar to support the sustainable development of the industry. The paper addresses aquaculture in the Black Sea from different perspectives: it outlines the key characteristics of the Black Sea environment; it discusses the most common farmed aquatic species and the potential for new ones; it frames the national approaches to aquaculture development, sharing information about success stories, while shedding light on the main challenges and priorities ahead. This collective endeavour will represent a helpful contribution to Black Sea riparian countries to answer the many questions they have, and expectations they hold from the aquaculture sector.

Heavy metal exposure to biota has become a severe thread to the environment, as its bioaccumulation, toxicity and persistence is happing at an alarming rate. Heavy metal presence in water bodies has been reported by various researchers. Henceforth their exposure to aquatic organisms is certain. An investigation on the possible toxicological impact of Zinc sulphate on fish Clarias batrachus is carried out in laboratory. Histology of gall bladder was used as a marker for evaluation of toxicity after sub lethal exposure. Fish were exposed to sub-lethal concentrations of 5mg/L, 10mg/L and 15mg/L for 20 days. Simultaneous control was also maintained. Principle histological alterations were deformities in the normal structures of columnar epithelial line, muscular layer, and mucosal folds. 15mg/L and 20mg/L exposure of zinc sulphate altered the sub mucosa besides leading the formation of bile crystals, an indication of water loss. The severity of histopathology was exposure dependent. Histopathological alteration in gall bladder can be regarded as sensitive biomarkers of Zinc sulphate toxicological manifestations hence can be utilized for ecotoxicological biomonitoring of aquatic bodies.

Artemia salina cysts harvested from the Sebkha of Sidi El Hani were hatched and cultivated in the laboratory. The obtained nauplii were acclimated at 90 ppt and fed with Dunaliella salina microalgae until the adult stage called generation 1 (G1) was reached. Ten couples were isolated and acclimated in the same conditions. Observations of the offspring lasted for a maximum of 60 days. Cysts obtained from G1 were collected and counted. Cyst diameter, chorion thickness and hatching percentage were established. Nauplii obtained from G1 were labelled G2. The third (G3) and the fourth (G4) generations were studied similarly. A significant variation of untreated cyst diameter between G1 (234.7±14.1 µm) and the subsequent generations, notably G3 (210.9±14 µm) were registered. Decapsulated cyst diameter delayed significantly from 218.5±12.8 (G1) to 190.8±10.1 (G3). The chorion thickness ranged between 8.1 (G1) and 10.5 (G2). Therefore, an interesting boost of untreated cysts hatching percentage was observed from 69±2.3% (G1) to 76±3.7% (G4). These results highlighted the variability of cyst diameter across successive generations, even cultivated under laboratory scale. An improvement of hatching quality was detected when environmental conditions became favorable.

Nile tilapia (Oreochromis niloticus) culture has been faced by challenges of prolific breeding and early maturity of mixed-sex tilapia that can be solved by the culture of all-male tilapia. A study was conducted to compare the growth performance, survival and condition factor of genetically male tilapia (GMT), sex-reversed tilapia (SRT) and mixed-sex tilapia (MST) cultured in earthen ponds. Fingerlings of initial weights ranging from 0.41 to 0.91 g for GMT, SRT and MST were stocked in 150 m2 earthen ponds in triplicates at 3 fish m-2 and fed on a 35% crude protein diet. After 180 days culture period, the final body weights of SRT (202.82±7.30 g) was significantly higher than GMT (174.34±3.71 g) and MST (148.06±4.60 g) (P<0.05). The survival of MST (74.11±4.73%) was higher than GMT (67.22±9.72%) and SRT (65.22±2.94%) but no significant differences were observed (P>0.05). The condition factor of all the fish was above 1 and was significantly different between the groups (P<0.05). This study demonstrates that SRT has superior growth performance than GMT and MST hence sex reversal should be used for improved Nile tilapia production.

The study tested a new feeding protocol to find out the best program using cheap and available products to enhancement the mass culture and the nutritional value of B. plicatilis. The feeding regime was six artificial treatments formulated from dried yeast (Saccharomyces cervisiae) with sucrose sugar and yeast with molasses in different concentrations. Additionally, a live Cyclotella sp. had been applied as supplementary food to each treatment and as independent treatment (control). B. plicatilis was cultured in small scale to find the best food regime and technique to apply it in the large one. B. plicatilis attained its highest density in the small scale culture (370 Ind.ml1 ) with T1 (30 % yeast, 70 % sugar and Cyclotella sp.) at the 12th day, while the highest population growth rate (PGR) (0.65) was calculated at the 9th day. According to the analysis of variance (ANOVA) and PGR, T1 had been applied in the large scale culture. B. plicatilis samples were composed of 51.6% total protein with 16 amino acids and 33.01% total lipid with 19 identified fatty acids. The study concluded that the treatment (T1) is a suitable diet for enrichment the mass culture and the nutritional value of B. plicatilis.

Aquaponics is an emerging area of ecological aquaculture comprising diverse technologies that converge on integrating recirculating aquaculture and hydroponics in one production unit. It has made possible to simultaneously produce fish and vegetables with nutrient cascading and water conservation as among its core concepts. While production of these food items is the material output of the system, there is a complexity of processes involved which opens a vast scope for innovations. Production of fish and plants integrated in the aquaponics fluctuates depending on the various biodynamic links that influence the nutrient turnover and water quality across the unit. A successful operation of aquaponics production unit, therefore, requires a thorough understanding of the whole system as a functioning ecosystem comprising fish, plant and the nitrifying bacteria. These biological components differ in their optimum requirements but the overall homoeostasis of the composite system can be maintained through regulating the water quality and nutrient profiles by way of adaptive interventions for acceptable tradeoffs. Balancing of nutrients by appropriate rates of stocking of fed and extractor species, feeding based on nutrient composition and anticipated excreted nutrients are essential for sustainability of aquaponics. It deserves emphasis that with so many variables in the system, there is obviously a vast scope for unlimited diversification and innovations to improve the production efficiency and sustainability. Regions facing water stress or where conservation of water is a priority will particularly benefit from aquaponics.