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Carbohydrate utilization by fish varies with feeding habits and feed processing. Extruded aquafeeds have increased digestibility of carbohydrate sources resulting from the cooking and gelatinization of this nutrient, making it readily available for all aquatic species. This study aimed at determining the effects of extrusion cooking of feeds in the digestibility of different dietary carbohydrate sources for dourado. Isonitrogenous and isoenergetic diets (530 g kg−1 crude protein and 20.80 MJ kg−1 gross energy) containing either corn, toasted cassava flour, wheat flour, broken rice, cassava starch, or corn starch, in extruded or pelletized form and added of chromic oxide as inert marker, were fed to groups of juvenile dourado (73.97 ± 12.0 g; n = 40) stocked in 500-L polyethylene tanks. Extrusion cooking improved the digestibility of energy and/or starch of corn, cassava starch, wheat flour, rice and corn starch ( P < 0.05), but did not affect digestibility of toasted cassava flour ( P > 0.05). It is thus fair to infer that dourado, despite being a carnivorous species, is properly fit to digest wheat flour, rice and corn starch in natural form. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the impact of diets with different plant protein ingredients on proximate composition, tissue metabolites and tissue fatty acid composition, as well as hepatic and intestinal histological modifications in Senegalese sole ( Solea senegalensis). Fish (21.5 ± 2.8 g body weight) were fed six isonitrogenous and isoenergetic diets during 11 weeks. A control diet containing fish meal as the main protein source was compared with five experimental diets replacing 30% fish meal protein by different plant protein sources: soybean meal ( SBM), soybean protein concentrate ( SPC), soybean protein isolate ( SPI), wheat gluten meal ( WGM) or pea protein concentrate ( PPC). The inclusion of different plant protein did not significantly affect growth and proximate composition of fish. The hepatosomatic index was not significantly different to the control group; however, utilization of WGM significantly increased hepatocyte size. Plasma protein values and muscle triglycerides were influenced by the inclusion of SBM and WGM in the diets respectively. Feeding fish on SBM, WGM and PPC diets significantly enhanced n-6 fatty acid levels in muscle, particularly linoleic acid. None of the plant protein ingredient used in the diets decreased arachidonic, eicosapentaenoic as well as docosahexaenoic acid values in liver and muscle. Overall, histological studies did not reveal the existence of any intestinal alterations induced by the inclusion of different plant proteins. Despite moderate changes produced by SBM, SPC and WGM, inclusion of dietary plant protein ingredients has no major impact on growth, tissue and blood biochemistry, fatty acid profile and gut integrity of Senegalese sole juveniles. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the ontogenetic development of the digestive tract and its accessory structures (liver, pancreas, and gall bladder) in agastric larval Chinese sucker Myxocyprinus asiaticus with the histological and ultrastructural approaches from hatching to 56 days after hatching ( DAH). On the basis of its feeding mode, and analyzing the main histological features of the digestive system, larval development in Chinese sucker was divided into three stages from hatching: stage 1 (endotrophic period): 1-6 DAH; stage 2 (endoexotrophic period): 7-14 DAH; stage 3 (exclusively exotrophic period): from 15 DAH onward. At hatching, the digestive tract of the larvae consisted of an undifferentiated straight tube. At 4 DAH, the mouth opened, and the digestive tract was differentiated into buccopharyngeal cavity, esophagus and intestine. At 7 DAH, fish started to feed exogenously. Yolk sac was completely exhausted at 15 DAH. Until 56 DAH, the digestive tract of the larvae displayed regularly arranged microvilli, abundant vacuoles, and protein inclusion bodies. The pancreas, liver, and gall bladder were functional from 6 DAH, which enabled larvae to ingest, digest, and assimilate the first exogenous food. In comparison with teleosts that have a stomach, the development of the digestive tract of the agastric Chinese sucker seemed relatively slow. [ABSTRACT FROM AUTHOR]

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.

The article presents a research on the ontogenetic dietary shift of yellowstripe goatfish Mulloidichthys flavolineatus from a coral reef at Reunion Island, Southwestern Indian Ocean. The study aims to analyze the muscle composition and the contents of the stomach to look into the size-related dietary changes and habitat partitioning. The goatfishes are widely spread into shallow-water ecosystems. Accordingly, the study utilized juveniles, young adults and adult goatfish wherein they demonstrated a diet gap between the juveniles and young adult. Moreover, the static isotopes indicate that there is prevailing amount of macrofauna because of the possible selective breeding of the goatfishes.