This study aimed to investigate the effects of different concentrations of fructooligosaccharide (FOS) instead of glucose (GLU) as the carbon source in the biofloc system. GLU was used as the carbon source in the control group, and 2.5
Fish diseases caused by parasites are considered one of the major causes of mortality in aquaculture, which can harm fish of various life stages from juvenile to adult fish. The study of fish diseases in the People's Republic of China started from the identification of a flagellated parasite Cryptobia branchiaslis Nie, 1955, which led to severe disease and death of grass carp fingerlings. During the past seventy years (1953–2023), China has made tremendous achievements in fish parasitology and developed a complete scientific system. In this paper, seventy years of research progress and achievements of freshwater fish parasitology in China are reviewed from four aspects, including pathogen biology, ecology, pharmacology, and immunology. Prospects for future development trends and cutting-edge hotspots are also discussed herein. This article provides readers majoring in fish parasitology and other related fields with comprehensive materials to fully understand the history, current status, and future development trends of fish parasitology in China.
The Yangtze River is the mother river of China. To promote the aquatic ecosystem protection of the great river, the Project of Yangtze Fisheries Resources and Environment Investigation (2017–2021) supported by the Ministry of Agriculture and Rural Affairs, P. R. China carried out by 24 institutes and universities that located in the Yangtze River basin surveys the status of (1) fish species composition and spatial distribution, (2) current fish abundance, (3) endangered fishes, (4) Yangtze finless porpoise, (5) aquatic eco-environments, (6) water-level fluctuation areas, (7) capture fisheries and recreational fisheries of the Yangtze River mainstream and 10 of its main tributaries, including Yalong River, Heng River, Min River (including Dadu River), Chishui River, Tuo River, Jialing River, Wu River, Han River, Dongting Lake and Poyang Lake. The results showed that there were 443 fish species (belonging to 163 genus, 37 families, and 18 orders) before 2017, but only 323 fish species (including 15 new recorded exotic species) were recorded in the project of 2017–2021. Among them, Cyprinus carpio, Carassius auratus, Hypophthalmichthys molitrix, Pelteobagrus fulvidraco, Coilia brachygnathus, Silurus asotus, Saurogobio dabryi, Ctenopharyngodon idellus, Pelteobagrus nitidus, Hemiculter leucisculus, Siniperca chuatsi, Coreius heterodon, Culter alburnus, Parabramis pekinensis, and Aristichthys nobilis were the dominant species across the whole Yangtze River system. It is estimated that there were 886 million individuals weighing 124.8 million kg, merely equivalent to 27.3% of the resources in 1950s, 30.9% of the resources in 1960s, or 58.7% of the resources in 1980s. In the new list of protected fishes that recorded in the Yangtze River system, only 15 of 29 were collected in this project of 2017–2021. Psephurus gladius has been affirmed to be Extinct by International Union for Conservation of Nature (IUCN). The wild individuals of Tenualosa reevesii and Luciobrama macrocephalus have disappeared for many years and maybe have been extinct already. Acipenser dabryanus has been affirmed to be Extinct in the Wild by IUCN. The natural propagations of A. sinensis, Myxocyprinus asiaticus and Trachidermus fasciatus have been interrupted for many years. The populations of Yangtze finless porpoise in the Yangtze River mainstream, Dongting Lake and Poyang Lake have steadily rising sizes and expanding distributions in 2017–2021. Parts of them migrate from one region to another with the seasons, which would result in the fluctuation of Yangtze finless porpoise population within some regions. The conventional indicators of water quality in the Yangtze River system were good and conformed to the water quality criteria of fishery in 2017–2021. In the last 40 years, the maximum surface water area in the Yangtze River basin extended to approximately 63,360 km2, the minimum surface water area covered approximately 26,396 km2, and the seasonal water-level fluctuation areas occupied approximately 36,964 km2. Compared with 1984–2000 period, the 2001–2020 period witnessed an overall decreasing trend in the frequency of surface water occurrence within about 25,869 km2 of aquatic areas. From 1984 to 2000 period to 2001–2020 period, permanent surface water has decreased by nearly 8,750 km2. In 2017, the fishermen were mainly 40–60 years old and their educational levels were mainly lower than junior high school. In 2017, most anglers were older than 40 and used hand rod and/or sea rod. Their average catch of each time was mainly less than 1 kg. Results suggested that the fishing ban in key waters of the Yangtze River basin is not only an ecological project of aquatic ecosystem conservation, but also a livelihood project for the fisherman to embrace industrial transformation and improve their living conditions. After the implementation of the fishing ban, the fisheries resources would gradually recover, and the Yangtze finless porpoise population size would also see a steady increase. However, the endangered species would remain threatened for a long time. The degraded waterbodies and water-level fluctuation areas would be the key restrictive factors for future aquatic ecosystem recovery in the Yangtze River basin. Since this survey was carried out before the fishing ban, the current results could provide a baseline for future evaluation of the effect of the Yangtze River fishing ban.
In order to understand the effect of brackish water and fresh water culture modes on the nutrient accu-mulation of Coilia nasus cultured in pond,the muscle nutritional composition and quality of Coilia nasus ecologic-ally cultured in brackish water(salinity 10-15)and freshwater(0.4-1.0)model were investigated and analyzed by biochemical analysis methods.The results show that the muscle crude fat content(7.27%)of C.nasus cultured in brackish water mode was significantly higher than that of freshwater mode(4.30%),while the muscle moisture(72.54%)and crude ash content(1.32%)of brackish water mode were significantly lower than that of freshwater mode(76.85%and 2.06%,respectively),No significant difference in the crude protein content of muscle was found between two cultural modes.Except that no significant difference in tryptophan and cystine was found between the two cultural modes,the contents of other 16 amino acids of brackish water mode were significantly lower than those of fresh water mode;the total amino acid(TAA),total essential amino acid(EAA),total half-essential amino acid(HEAA),total non-essential amino acid(NEAA),and total delicious amino acid(DAA)con-tents of brackish water mode were significantly lower than those of fresh water mode,and there was no significant difference in the EAA/TAA and EAA/NEAA specific values of C.nasus muscle between two cultural modes,while the DAA/TAA specific value(40.32)of brackish water mode were significantly lower than that of fresh water mode(40.68).The essential amino acid index(EAAI)(58.59)of brackish water mode was lower than that of fresh water model(72.04),while the specific value of branched amino acids to aromatic amino acids(F value)(2.44)of brackish water mode was higher than that of fresh water mode(2.35).In the 28 kinds of fatty acids detec-ted,there was no significant difference in the contents of 11 kinds of fatty acid between two cultural modes.In major fatty acids,C16:0,C18:0,C18:1n9c,C22:5n3(DPA)and C22:6n3(DHA)contents of brackish water group were significantly higher than that of fresh water group,while the C18:2n6c and C18:3n3 contents of brackish water mode were significantly lower than those of fresh water mode.SFA,MUFA and EPA+DHA contents of brackish water mode were significantly higher than those of fresh water mode;∑n3PUFA/∑n6PUFA(3.93)of brackish water mode was significantly higher than that of fresh water model(2.10),this is consistent with the fact that n3PUFA/n6PUFAs of migratory fish muscle is higher in seawater and lower in freshwater.Therefore,the muscle protein of C.nasus cultured in fresh water is more nutritious and delicious,while brackish water culture is beneficial to the accumulation of fat and the retention of the MUFA(especially C18:1n9c)in C.nasus.The osmotic pressure of brackish water may be near the isotonic point of C.nasus,and this is more conducive to the accumulation of nutrients and the growth of C.nasus.It is suggested that brackish water should be used in the commercial fish culture stage of C.nasus and fresh water should be used in the intensive culture stage of C.nasus before the sales.
To explore the feeding effect of fermented formula feed in red swamp crayfish(Procambarus clarkii),unfermented and fermented feeds were fed to juvenile P.clarkii[initial body weight(4.91±0.18)g]in an indoor circulating water system for eight weeks.The effects of fermented feed on growth,muscle quality,digestion,anti-oxidant capacity,and intestinal flora structure of P.clarkii were analyzed.The results showed that,① the dissolu-tion rate of fermented feed was significantly lower than that of unfermented feed.② The fermented diet signific-antly increased weight gain rate,and specific growth rate.Furthermore,it decreased feed conversion ratio,but had no significant effect on survival rate,hepatosomatic index(HSI),flesh content,and body composition.③ The fer-mented diet significantly improved muscle hardness,elasticity,chewiness and stickiness of P.clarkii,and decreased adhesion.④ The fermented diet significantly increased the activities of trypsin and lipase in hepatopan-creas and intestinal tract,the activities of superoxide dismutase,acid phosphatase,and alkaline phosphatase in serum and hepatopancreas,and the total antioxidant capacity of the hepatopancreas.⑤ The fermented feed signi-ficantly increased the length and width of intestinal villi.⑥The fermented feed improved the intestinal microbial structure of P.clarkii,significantly increased the relative abundance of Firmicutes and Actinobacteria,and increased the diversity of intestinal flora.Overall,the fermented feed effectively improved the growth perform-ance,muscle quality,digestion,and antioxidant capacity by improving the intestinal tract tissue structure and chan-ging the structure of intestinal microorganisms of P.clarkii.
