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Elasmobranchii shows particular characteristics that make them susceptible to the impacts caused by fishing pressure, especially bottom trawling, which mostly affect rays, as they have demersal habits. Based on food availability and feeding ability, Polychaeta and Sipunculiforme are the bases of Brazilian electric ray Narcine brasiliensis diet. Morphologically, the digestion starts in the oesophagus with acid mucines action. The existence of acid and neutral mucines in the posterior intestine prevents lesions in the mucosa and favours the passage of faeces and shell residues. Thus, this study shows the interaction between their habitat, the organisms and their morphophysiology. [ABSTRACT FROM AUTHOR]

Abstract: A 10-week feeding trial in seawater floating cages (1.5×1.5×2.0m) was conducted to investigate the effects of dietary canola meal (CM) levels on growth, survival, digestion and selected immune parameters of Japanese seabass (initial average weight 8.3±0.15g). Six isonitrogenous (crude protein 43%) and isoenergetic (20kJg− 1) practical diets were formulated by replacing 0 (the control), 10, 20, 30, 40, and 50% of protein from fish meal with CM. Each diet was randomly fed to triplicate groups of fish, and each cage was stocked with 20 fish. Fish were fed twice daily (06:30 and 16:30) to apparent satiation. The results showed that with increasing dietary CM levels, the survival, specific growth rate (SGR) and feed efficiency (FE) decreased. The survival was significantly lower compared to the control group (P <0.05) with a 40% substitution level. Fish fed the diet with 20% or more protein from CM had significantly lower SGR than the control group (P <0.05), but there was no significant difference in FE at this level (P >0.05). The activities of digestive enzymes and apparent digestibility coefficients of dry matter, protein, lipid and phosphorus significantly decreased with increasing dietary CM level. A similar trend was observed in the immune response where lysozyme activity significantly decreased compared with the control group when the substitution level was more than 20%. Results of the present study indicated that protein from CM could substitute less than 20% for fish meal protein without influencing the growth of Japanese seabass. The higher substitution levels of CM induced negative influences on growth, survival and serum lysozyme of Japanese seabass. [Copyright &y& Elsevier]

The article discusses research done on feeding habits and niche separation among several deep-sea chimaeroid fishes found in Chatham Rise, New Zealand, including Hydrolagus (H.) novaezealandiae, H. bemisi and Harriotta (H.) raleighana. The study procedure included the examination of the digestive tract contents of the fishes, which were fed on benthic infauna and epifauna. Results revealed that the diets of H. novaezealandiae, H. bemisi and H. raleighana were characterized by crabs and sea urchins, by crabs and polychaetes, and by polychaetes and molluscs, respectively.

Five iso-nitrogenous (300 g crude protein kg−1 diet) semi-purified diets with graded levels of carbohydrate at 220 (D-1), 260 (D-2), 300 (D-3), 340 (D-4) and 380 (D-5) g kg−1 diet were fed ad libitum to Puntius gonionotus fingerlings (average weight 0.59±0.01 g) in triplicate groups (20 fish replicate−1) for a period of 90 days to determine the effect of the dietary carbohydrate level on the growth, nutrient utilization, digestibility, gut enzyme activity and whole-body composition of fish. Fifteen flow-through cement tanks of 100 L capacity with a flow rate of 0.5 L min−1 were used for rearing the fish. The maximum weight gain, specific growth rate, protein efficiency ratio, RNA:DNA ratio, whole-body protein content, protease activity, protein and energy digestibility and minimum feed conversion ratio (FCR) were found in the D-2 group fed with 260 g carbohydrate kg−1 diet. The highest protein and energy retention was also recorded in the same group. However, from the second-order polynomial regression analysis, the maximum growth and nutrient utilization of P. gonionotus fingerlings was 291.3–298.3 g carbohydrate kg−1 diet at a dietary protein level of 300 g kg−1 with a protein/energy (P/E) ratio of 20.58 −20.75 g protein MJ−1. [ABSTRACT FROM AUTHOR]

Examines the effects of diet on gastrointestinal microbial community of fish. Number of viable aerobic and facultative aerobic bacteria associated with the digestive tract; Isolation of the bacterial species; Influence of dietary manipulation on the species composition of carnobacteria.