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A 14-week trial was undertaken to examine the effects of coenzyme Q10 (CQ10) and l -carnitine (LC) dietary supplementation, either individually or in combination, on the feed intake, growth, blood biochemistry, immunity, economic viability, and body composition of Nile tilapia fingerlings reared at a high stocking density. The study involved eight groups of 450 tilapia juveniles, with an average weight of 6.083 ± 0.09 g, assigned to different treatments. Two groups were fed a basal diet and stocked at densities of 30 and 60 fish per m3, respectively. The remaining groups were reared at a high stocking density of 60 fish/ m3 and fed diets fortified with LC at 150 mg (G3), LC at 300 mg (G4), CQ10 at 20 mg (G5), CQ10 at 40 mg (G6), LC at 150 mg + CQ10 at 20 mg (G7), or LC at 300 mg + CQ10 at 40 mg (G8) per kg of diet. The findings revealed that high stocking density had an adverse impact on tilapia growth performance. Nevertheless, the inclusion of LC and CQ10 in the diet, whether separately or in combination, significantly improved growth parameters and enhanced survival rates. The G6, G7, and G8 groups showed the most significant improvements in growth and survival. High stocking density resulted in decreased moisture and crude protein content, while LC and CQ10 supplementation increased these components and reduced crude fat and ash content. High stocking density negatively impacted blood metabolites, leading to elevated levels of aspartate aminotransferase, alanine aminotransferase, creatinine, and urea-N, as well as decreased total protein and albumin. However, supplementation with LC and CQ10 effectively alleviated these effects, improving the levels of these parameters. All supplemented groups showed enhanced lysozyme activity and IgM concentration, with the greatest improvements observed in the G6, G7, and G8 groups. Economic analysis indicated that LC and CQ10 supplementation improved final and relative margin, except in the G4 group. In conclusion, the combined supplementation of LC and CQ10 shows promise in enhancing productivity and profitability in tilapia farming under high stocking density conditions, particularly in concrete tanks. • Combined l -carnitine (LC) and coenzyme Q10 (CQ10) exhibited the highest improvements in growth and immunity. • Supplementation of fish diets with LC and/or CQ10 resulted in increased growth and a decrease in mortality rate. • The addition of LC and/or CQ10 to tilapia's diet improved the immune response and blood biochemical indicators. • Including 40 mg of CQ10 in the diet had the highest economic efficiency. [ABSTRACT FROM AUTHOR]

Non-optimum temperature results in stress in fish through different biological and physiological processes. This study investigated how early mild stress (EMS) and temperature can influence growth, hematology, blood biochemistry, immunological response, antioxidant system, liver enzymes, and stress response of juvenile oscar (Astronotus ocellatus ; 8.02 ± 0.81 g) before and after acute confinement stress (AC stress). Eight experimental treatments were 17D (farmed at 17 °C), 22D (farmed at 22 °C), 27D (farmed at 27 °C), 32D (farmed at 32 °C), 17DES (farmed at 17 °C and EMS), 22DES (farmed at 22 °C and EMS), 27DES (farmed at 27 °C and EMS), and 32DES (farmed at 32 °C and EMS). At the end of the experiment (nine weeks), there was no significant difference in survival rate, feed conversion ratio, body composition, and survival rate after the AC stress (ten weeks). The growth rates in the 17 and 32 °C groups were lower than others, showing the negative effect of temperature being too high or too low. After nine weeks, fish farmed at 32 °C had the highest hematological parameters (hematocrit, hemoglobin, red blood cells, and blood performance) and liver enzymes (lactate dehydrogenase, alanine transaminase, and aspartate transaminase). This group also has the lowest lysozyme, alternative complement pathway (ACH50), immunoglobulin, complement C3, complement C4, superoxide dismutase, and glutathione peroxidase. The EMS did not positively or negatively affect fish physiology in this study. In conclusion, the optimum temperature for oscar to achieve the best growth performance, immune response, and health status is 22–27 °C. • Excessive high (32 °C) or low (17 °C) temperatures decreased growth and survival of fish. • The early mild stress did not positively or negatively affect fish physiology in this study. • Fish farmed at 32 °C had the highest hematological parameters and liver enzymes. [ABSTRACT FROM AUTHOR]

This study investigates the basis of the stimulatory effects of thyroxine (T4) on the growth and physiological changes in Sterlet sturgeon broodstock and their larval offspring. Groups of fish received four injections of 0, 1 or 10 mg kg BW−1 of T4 over a 170-day period. At the end of trial, blood was taken and plasma biochemical parameters, sex steroid and thyroid hormone (THs) levels were measured. Broodstock were induced to ovulate by the injection of LHRHa2 and ovarian fluid (OF) and eggs were obtained through a minimally invasive surgical technique. The eggs were fertilized and resulting larvae were assessed after 14 days of grow out. Weight gain, protein and lipid efficiency and food efficiency of broodstock in T 10 were higher than the other treatments (P < 0.05). The cholesterol, triglyceride, total protein, albumin and glucose levels in OF were higher in the T 10 group than the other groups (P < 0.05). Similarly, calcium, magnesium and phosphorus concentrations in the OF of the T 10 group were higher than the other treatments. Furthermore, plasma cholesterol, triglyceride, HDL, VLDL and calcium levels were significantly enhanced in the T 10 group compared to the other groups, while, plasma phosphorus and magnesium were not significantly affected. Additionally, the T 10 group displayed lowest LDL plasma levels (P < 0.05). The highest and lowest concentrations of testosterone and 17β-estradiol were recorded in T 10 group. Moreover, the highest levels of TH were found in T 10 , while, control group had the lowest TH concentrations. The offspring from the T 10 treatment had the lowest mortality rate at 3 dph. This study highlights that 10 mg T4 kg BW−1 promoted biochemical and metabolic changes in the adult Sterlet broodstock that were associated with enhanced egg fertility and larval survivability. • Knowledge of the effects of Thyroxine (T4) on physiological performance of sturgeon species is scared. • T4 enhanced Sterlet sturgeon growth performance. • High doses of T4 led to the increase in plasma concentrations of thyroid hormones. • T4 administration had great impacts on blood plasma biochemistry. • Fish in the high doses of T4 had significantly greater levels of ovarian fluid Ca2+, P and Mg2+ than the other experimental groups. • The findings could assist to improve the fertilization and survival rate of Sterlet sturgeon. [ABSTRACT FROM AUTHOR]

Abstract The effects of different feeding strategies on the growth rate and hematology of Lophiosilurus alexandri were investigated. An experiment was carried out at the Laboratório de Aquacultura, Universidade Federal Minas Gerais, with nine hundred juvenile L. alexandri (length 4.3 ± 0.3, weight cm 0.9 ± 0.2 g) fed exclusively extruded dry diet and kept in fifteen 30-L cultivation tanks in a recirculating aquaculture system. The design was completely randomized with five replicates of each of three feeding treatments: every day of the week (control), six days of the week (F6:1) and five days of the week (F5:2). The following were calculated at the end of the experiment: survival, daily weight gain (DWG), total length (TL), daily feed intake (DFI), feed conversion rate (FCR), specific growth rate (SGR), final body weight (FBW), condition factor (K), protein efficiency ratio (PER), nitrogen retention (NR) and the hepatosomatic index (HSI). Blood samples were taken after 42 days (prior to feed restriction) and at 45 days (after feed restriction of one or two days), and levels of hematocrit, total plasma, hemoglobin, erythrocytes, leukocytes glucose, cholesterol and triglycerides determined. Data were submitted to ANOVA and means compared by the Tukey test (5%). No significant differences were found for survival, FCR, DWG, TL, FBW, K, and SGR. The highest DFI and HSI values were recorded in the control treatment, while PER and NR were highest in the F5.2 treatment. The highest hematocrit values were observed for the control and F6:1 treatments. In all treatments, the values for hematocrit, total protein, leukocytes and glucose were lower after fasting. The highest values for leukocytes were for the control and F6.1 treatments prior to fasting, while after fasting the control treatment was highest. For the F5:2 treatment, the highest value for erythrocytes was after fasting. The highest values for cholesterol were after fasting for all treatments. In conclusion, L. alexandri exhibits compensatory growth in relation to the two short-term food restriction treatments tested. The species adapted to dietary strategies and maintained hematological and biochemical parameters close to those of the control groups when returned to feeding. Highlights • Studies about feed restriction are essential for enhancing fish farms; • L. alexandri experienced compensatory growth after the two short-lived feed restriction regimens tested; • The species demonstrated adaptation to different dietary strategies; • The animals are able to maintain hematological and biochemical parameters close to those of the control treatment; • Individuals of this species can be fed five times a week without negative effects on growth and survival. [ABSTRACT FROM AUTHOR]

Changing trends in fish feed formulation, with progressively higher inclusion levels of plant ingredients, are invariably introducing more fibre despite the fact that this component cannot be utilized by most fish. The effects of increasing insoluble dietary fibre level on growth, nutrient utilisation, blood parameters and gut health in European sea bass ( Dicentrarchus labrax L.) were studied over a period of 117 days. Moreover, investigation on digesta transit time through gastrointestinal evacuation pattern and digesta characteristics (moisture of digesta) were studied. Five isoproteic diets were formulated to contain increasing insoluble fibre levels, neutral detergent fibre, NDF (7.2, 8.9, 11.5, 13.1 and 15.5%) derived by the inclusion of sunflower hulls and soybean hulls. No significant differences due to fibre inclusion levels were observed in final body weight, specific growth rate, feed intake, feed conversion rate, protein and lipid efficiency. No significant differences in serum total protein, glucose, triglycerides, alkaline phosphatase and inorganic phosphorous were found. All the histological sections showed normal intestinal architecture, and inflammatory and/or degenerative changes were not present in any histological section from all subjects examined. The investigation into gastrointestinal evacuation pattern revealed no significant differences between treatments, however higher dietary fibre levels seem to increase the time required to empty the stomach while the time required to empty 90% of the hindgut content was similar in all the treatments: around 46–47 h. No differences were found between diets in the moisture content of digesta along the digestive tracts. We can conclude that the different insoluble fibre levels tested in this trial have no effects on overall performances and feed efficiency in European sea bass. Results from blood biochemistry profile and histology confirm good nutritional and health status of fish under all feeding treatments. The inclusion of fibre had no influence on digesta transit time. In formulation of feed for the on-growing of European sea bass insoluble fibre derived from sunflower hulls and soybean hulls can be included at a level of up to 15.5%. [ABSTRACT FROM AUTHOR]

In this study, an 8-week feeding trial was performed to evaluate the effects of dietary metformin inclusion on the growth performance, body composition, glucose homeostasis and liver histology of juvenile largemouth bass Micropterus salmoides (LMB) fed high starch diets. Using a 2 × 2 factorial design, four isoproteinic (50%) and isolipidic (13%) diets were formulated with two starch levels (9% and 14%) with or without 0.25% metformin inclusion at each starch level. Each diet was assigned to triplicate tanks of LMB with an initial body weight of 10.8 g. The results showed that an increase of dietary starch from 9% to 14% retarded the growth performance (weight gain ratio and specific growth rate) of LMB through impairing feed utilization (feed efficiency ratio, protein efficiency ratio and protein productive value). Though feed consumption increased, the growth performance of LMB did not benefit from dietary metformin administration as a result of the impaired feed utilization. Both the glucose homeostasis (fasting blood glucose) and glucose tolerance of LMB were impaired with increasing dietary starch from 9% to 14%. However, LMB metabolically adapted well to high starch diets through stimulating glycolysis and glycogen synthesis while inhibiting gluconeogenesis in the liver at the molecular level. Moreover, an increase of dietary starch from 9% to 14% upregulated hepatic lipogenic capacities while down-regulated fatty acid oxidation thereby promoting lipid deposition in the liver and whole fish. Dietary metformin improved the glucose homeostasis and glucose tolerance of LMB through promoting glycolysis and de novo lipogenesis rather than glycogen deposition in the liver. However, dietary metformin did not mitigate the liver injuries (the activities of alanine aminotransferase and aspartate aminotransferase in the plasma along with histological appearance) in LMB fed high starch diets. In conclusion, our results demonstrated that dietary metformin inclusion did not mitigate the growth retardation and liver injury of LMB fed high starch diets, but improved the glucose homeostasis and glucose tolerance through promoting the glycolytic and lipogenic pathways in the liver. • Feeding high starch diets induced growth retardation and liver injury in LMB. • At the molecular level, hepatic glycolipid metabolism of LMB adapted well to high starch diets. • Dietary metformin improved postprandial glucose homeostasis of LMB through promoting hepatic glycolysis and lipogenesis. • Dietary metformin did not mitigate the liver injury of LMB fed high starch diets. [ABSTRACT FROM AUTHOR]

This work aims to evaluate the tolerance, growth, metabolism, hematology and blood biochemistry of juvenile Lophiosilurs alexandri exposed to different water salinities. In Experiment 1, juveniles (28.6 ± 1.3 g weight and 12.8 ± 1.8 cm length) were transferred directly from freshwater to water with salinities of 0 (freshwater), 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0 g of salt/L, and observed for 96 h. In Experiment 2, juveniles (15.5 ± 0.8 g weight and 11.0 ± 1.0 cm length) were subjected to saline treatments of 0 (freshwater), 2.5, 5.0, 7.5 and 10.0 g of salt/L for 28 days with, juveniles being acclimated gradually every 6 h, to reach the desired salinity levels in 24 h. In Experiment 1, at 24 h of osmotic shock, the CL 50 -24 h was estimated to be 11.6 g of salt/L. At the end of 96 h, the survival rate was 100% up to salinity 7.5 g of salt/L, while at 10.0 g of salt/L it was 58.3%. Total mortality occurred with 12.5 and 15 g of salt/L. At 24 h, changes in glucose, hemoglobin, osmolarity, hematocrit, cortisol, alanine aminotransferase and chloride ions were recorded. However, there were no significant differences in total plasmatic protein, triglycerides, cholesterol and albumin (p > 0.05). In Experiment 2, there was total mortality on the 21st day of the experiment with 10 g of salt/L. At 28 days, the survival rate was 100% between freshwater and 5 g of salt/L. In terms of biomass gain and feed conversion, a quadratic response with higher estimated levels at 2.01 and 2.45 g of salt/L were recorded, respectively. Weight gain, daily weight gain and specific growth rate were constant until the estimated values of 2.64, 2.63 and 2.83 g of salt/L, respectively, then decreasing in higher salinities. For whole fish composition, phosphorus and protein exhibited a quadratic response with the highest level estimated at 3.24 g of salt/L and the lowest estimated level at 0.98 g of salt/L, respectively. Constant values for energy were recorded until the estimated salinity at 2.15 g of salt/L. Comparing the hematological and biochemical data between 24 h and 28 days, several differences were found relating to time, salinity and the interaction between these factors, depending on the variable analyzed. Water salinity has direct implications for hematological, biochemical, performance and carcass composition of juvenile L. alexandri . Salinities up to 7.5 g salt/L for short time periods (96 h) to diseases treatments or transport and 2.5 g/L in longer time periods (28 days) to cultivation indoor can be used for juvenile L. alexandri . [ABSTRACT FROM AUTHOR]

Four isoproteic/isolipidic plant protein-based diets were formulated to assess the lasting effects of feed additives and low fish meal (FM) and fish oil (FO) diet formulations on gilthead sea bream growth performance. FM was included at 23% in the control diet (D1) and at 3% in the other three diets (D2, D3, D4). Added oil was either FO (D1) or a blend of vegetable oils replacing 58% (D2) and 84% (D3, D4 diets) of FO. A commercial sodium butyrate preparation (NOREL, 70-BP) was added to the D4 diet at 0.4%. Each diet was allocated to triplicate groups of juvenile fish fed to satiety over an 8-month feeding trial (May–December). All fish grew efficiently from 15 g of initial body weight to 296–320 g with an overall feed efficiency (FE) of 0.95–1.01, although fish fed D3 and D4 diets showed transient growth impairments over the course of the first four weeks of the trial. Data on biometric indexes, whole body composition, haematology and blood biochemistry revealed a strong effect of sampling time in fish sampled at mid-summer (August) and late autumn (December). In contrast, the diet effect was mostly reduced to a few blood parameters. Low inclusion levels of FM reduced plasma haemoglobin levels (D2, D3), but these effects were reversed by butyrate supplementation (D4). The same phenomena occurred for total cholesterol with the highest circulating concentration of choline and IGF-I in fish fed the D4 diet during their summer growth spurt. At the transcriptional level, gene expression profiling of liver and skeletal muscle with a PCR-array of 87 growth markers provided additional evidence for an overall well-growth condition in all of the experimental groups. Up to 73 genes were found at detectable levels in the liver tissue, but only 13 were differentially expressed. Likewise, 84 genes were actively transcribed in the skeletal muscle, but only nine were differentially expressed in at least one experimental group. Butyrate supplementation reversed the up-regulated expression of inflammatory cytokines (TNFα) and muscle markers of cellular morphogenesis and protein breakdown (CDH15, CAPN3, PSMA5, PSMB1, UBE2N) in the muscle of fish fed the extreme D3 diet. These results support the use of low FM/FO diets alone or supplemented with feed additives, which have the potential to improve or reverse metabolic steady-states. Statement of relevance Butyrate effect on low fish meal/fish oil diets. [ABSTRACT FROM AUTHOR]

Fishmeal replacement with soy protein hydrolysate in diets for juvenile starry flounder ( Platichthys stellatus ) has been reported recently, but its application is limited due to high price and low yield. Whether it is feasible to replace dietary fishmeal protein (FMP) with cheap soy protein concentrate (SPC) for this fish remains uncertain. A feeding trial was conducted to investigate the effect of diets containing SPC on growth performance, oxidation resistance, health status, feed digestion and nutritional composition of juvenile starry flounder. Six isonitrogenous and isolipidic diets were formulated with SPC to replace 0% (S0, control), 20% (S20), 40% (S40), 60% (S60), 80% (S80) and 100% (S100) of FMP. Each diet was randomly assigned to triplicate tanks with 80 fish (initial weight 12.76 ± 0.2 g) per tank in a circulating water system. Fish were fed twice daily to apparent satiation for 10 weeks. At the end of the feeding trial, weight gain, specific growth rate, daily feed intake and survival rate were lower in fish fed diets S80 and S100 than in the other treatments. Feed efficiency ratio, protein efficiency ratio and condition factor were reduced by total FMP replacement (S100) compared to the control. The maximum FMP replacement for weight gain and protein efficiency ratio was estimated to be 54.86–59.02% using broken-line models. Moreover, serum lysozyme and superoxide dismutase activities decreased in fish fed diets S60, S80 and S100 versus S0, while aspartate aminotransferase, alanine transaminase and gamma-glutamyl transferase activities followed a reverse trend. Lower serum glutathione peroxidase corresponded to higher alkaline phosphatase activity in fish fed diets S80 and S100 versus S0. Serum total protein and albumin contents were reduced by total FMP replacement (S100), whereas cholesterol and low- and high-density lipoprotein cholesterol contents decreased with any diets containing SPC compared to S0. Pepsin and trypsin activities in the stomach, foregut and hindgut increased in fish fed S40 but decreased in fish fed S100. Amylase activity in the foregut was elevated by replacing at least 40% of FMP with SPC, while that in the hindgut increased with any diets containing SPC. Additionally, total FMP replacement reduced protein and fat contents but increased ash content of the whole fish compared to other treatments. These results indicated that SPC could be utilized effectively by juvenile starry flounder. FMP replacement with SPC by less than 40% is recommended for satisfactory fish growth and health. Statement of relevance Our work has proved that soy protein concentrate could be utilized effectively by juvenile starry flounder and less than 40% fishmeal could be replaced by soy protein concentrate with satisfactory fish growth and health. Present paper assesses the feasibility of replacement fishmeal with soy protein concentrate in diet for juvenile starry flounder. These results provided a basis for the formulation of a low-fishmeal diet in flatfish aquaculture. [ABSTRACT FROM AUTHOR]

Cyprinus carpio is a commercially important fish in the aquaculture of the Czech Republic, while Carassius gibelio is an invasive species combining sexual and gynogenetic reproduction and often entering breeding ponds. The occurrence of F1 hybrids of these two phylogenetically closely-related fish has recently been reported. The objective of this study was to investigate selected aspects of physiology, immunity and blood biochemistry (i.e. parameters reflecting health status and condition) in both parental species and their F1 hybrids, all of the same age. The morphology was intermediate between parental species. The majority of biochemical, physiological and immune parameters were primarily affected by sampling period. For these parameters, hybrids achieved an intermediate character between parental species, but for biochemical and immune parameters they were still more similar to common carp, i.e. the species in the paternal position. The intermediate glucose and cholesterol levels together with the intermediate intestine–body size index in hybrids suggest the role of genetic introgression in determining the range of food utilizable for C. carpio × C. gibelio hybrids as well as their nutritional status, metabolic activity, and energy intake. In spring, females of gibel carp and hybrids reached higher GSI when compared to common carp; however, no spring increase in calcium (important for egg development) was found in hybrid females. Leukocyte count and complement activity in hybrids were intermediate between parental species. IgM level was significantly higher in females in both sampling periods, probably reflecting the different costs of reproductive investment between genders. We propose that the intermediality of traits associated with health and condition status in hybrids resulting from genetic introgression may potentially represent some advantage for hybrid vigor. Our results also highlight the good condition status of C. gibelio and may indicate a potential risk of competition between this invasive species and the economically important C. carpio in breeding ponds. [ABSTRACT FROM AUTHOR]

This study evaluated the use of two chemotypes of the essential oil of Thymus vulgaris (EOTV) as anesthetics for Colossoma macropomum and their influence on physiology and feed consumption. Three experiments were performed using thymol (EOTV-T) and linalool (EOTV-L) chemotypes. Experiment 1 determined anesthesia induction and recovery times for juveniles exposed to different concentrations of EOTV-T and EOTV-L (0, 50, 100, 150, 200 and 300 mg/L). Based on the results of Experiment 1, two more experiments were performed. Experiment 2 evaluated the effects of 0 mg/L EO (only the solvent ethanol), 50 mg/L EOTV-T and 100 mg/L EOTV-L on blood parameters after induction and one hour after recovery. Experiment 3 evaluated the effects of 0 mg/L EO, 50 mg/L EOTV-T and 100 mg/L EOTV-L on feed consumption after handling. No mortality was observed in any of the experiments. In Experiment 1, increasing concentrations of EOTV-T and EOTV-L reduced anesthesia induction time and increased recovery time; EOTV-T induced anesthesia faster than EOTV-L. Experiment 2 found control hemoglobin levels to be above baseline after one hour of recovery; no difference was observed for hematocrit and total plasma protein. Soon after induction, the control treatment had higher glucose levels than the other treatments. After one hour of recovery, the EOTV-T and EOTV-L treatments had increased glucose levels, while those of the control treatment were reduced. Soon after anesthesia, juveniles anesthetized with EOTV-L had the lowest cholesterol level, while those anesthetized with EOTV-T had the highest level of triglycerides. Experiment 3 found no difference in feed consumption among treatments. The lowest feed consumption was in the first days after handling for all treatments, which increased over subsequent days of the experiment. It was concluded that EOTV-T and EOTV-L are promising anesthetics for juvenile C. macropomum and that the use of 50 mg/L EOTV-T and 100 mg/L EOTV-L causes anesthesia in these juveniles within ideal induction and recovery intervals. The use of EOTV-T and EOTV-L did not greatly influence blood parameters and did not affect feed consumption after handling. • Thymol and linalool chemotypes Thymus vulgaris caused anesthesia of L. Colossoma macropomum. • Thymol and linalool chemotypes T. vulgaris did not greatly influence blood parameters. • Thymol and linalool chemotypes T. vulgaris did not affect feed consumption after handling. [ABSTRACT FROM AUTHOR]

This study investigated the effects of photoperiod duration on growth, heamatological and blood biochemical parameters, and antioxidant capacity of largemouth bass (Micropterus salmoides). Triplicate groups of juvenile fish (33.22 ± 4.68 g) were kept in a recirculating aquaculture system and exposed to five different photoperiods [light/dark (L/D), h] as follows: 8L:16D; 12L:12D; 16L:8D; 20L:4D and 24L:0D. All the fish were fed a commercial diet at a fixed ratio of 1% body mass with daily inspection of the consumed feed. The experiment lasted 16 weeks and fish growth was monitored at 4-week intervals. The results revealed the significant effect of photoperiod duration on growth rate and feed utilization. The constant light exposure (24L:0D) benefited weight gain (WG) only during the first four weeks while thereafter negative impacts were noticed. At the end of the feeding trial, the highest WG and specific growth rate were obtained in the 8L:16D group which significantly differed from those of the 12L:12D and 16L:8D groups. Although fish feed intake was not influenced by photoperiod duration, better feed conversion ratio was found in the 8L:16D group. Moreover, the same group exhibited the highest hepatosomatic and gonadosomatic indices, and haemoglobin concentration. The highest plasma total protein and globulin concentrations were recorded for the 16L:8D group. Plasma glucose concentration decreased by prolongation of light duration while opposite trends were observed for plasma ammonia concentration and creatinine kinase activity. The highest alanine aminotransferase and aspartate aminotransferase activities were found in 20L:4D and 12L:12D groups, respectively. Moreover, plasma alkaline phosphatase activity significantly decreased in 12L:12D and 16L:8D groups. Longer light duration led to remarkable increase of thiobarbituric acid reactive substances (TBARS) concentration in fish liver, brain and gill indicating the incidence of oxidative stress. Likewise, boosted antioxidant responses were found in liver [glutathione (GSH) and glutathione S-transferase (GST)], brain (GST) and kidney (superoxide dismutase) as light duration extended. These findings suggest that 8 L:16D is favouring better growth, organosomatic index and antioxidant capacity of largemouth bass juveniles reared in RAS. • Growth, physiological status and antioxidant response in largemouth bass are significantly affected by different photoperiods • Constant light duration has limited benefits for the biomass boost of largemouth bass juveniles • Shorter light duration benefited growth and health status of largemouth bass juveniles during moderate period of culture. • Suitable photoperiod can be effectively used to increase efficiency of largemouth bass aquaculture. [ABSTRACT FROM AUTHOR]

In this study, barberry fruit extract (BFE) was used as an herbal feed additive at 0 (control), 150, 300, 600, and 750 mg/kg to evaluate growth performance, physiometabolic responses, and gene expression related to growth and appetite in Siberian sturgeon. The fish (N = 150; 29.7 ± 2.2 g) were fed with the experimental diets for 56 days. Upon the completion of the feeding trial, the fish fed with BFE at 750 mg/kg showed higher growth indices than the control fish and the lowest feed conversion ratio (P < 0.05). The highest levels of red blood cell, hemoglobin, and hematocrit were observed in the group fed with 750 mg/kg BFE (P < 0.05). Different dietary levels of BFE had no significant effect on the levels of alkaline phosphatase and alanine aminotransferase in the serum samples (P > 0.05), while a decreasing trend was seen in aspartate aminotransferase, lactate dehydrogenase, glucose, and triglyceride contents by increasing in the dietary levels of BFE. The activities of lipase, amylase, and protease in the BFE-added groups were higher than the control group (P < 0.05). The highest expression of growth hormone gene was recorded in 600 and 750 mg/kg BFE treatments (P < 0.05). The transcription of insulin-like growth factor-I gene was significantly up-regulated in 750 mg/kg BFE treatment compared to others (P < 0.05). Ghrelin gene expression was significantly elevated in both brain and stomach tissue samples by increasing dietary levels of BFE. Overall, dietary BFE markedly at 750 mg/kg exerts growth-promoting effects in Siberian sturgeon. • Dietary effect of barberry fruit extract (BFE) in Siberian sturgeon was evaluated. • Growth rate and feed utilization of the fish fed with BFE were improved. • Hematological and serum biochemical parameters were positively affected by dietary levels of BFE. • The transcriptions of GH , IGF-1 , ghrelin genes were upregulated by supplementing the fish diet with BFE. • The best dietary dose of BFE was 750 mg/kg to achieve maximum performance. [ABSTRACT FROM AUTHOR]

The proportion of remaining stomach meal (PSR), gastric evacuation model, serum cortisol and glucose levels, intestinal lipase, amylase, and chymotrypsin activities and the expression levels of neuropeptide Y (npy), orexin (ore) and leptins (lepa , lepb) of the hybrid grouper (Epinephelus moara ♀ × E. lanceolatus ♂) during gastric evacuation were evaluated to determine the optimal feeding interval. Results showed that PSR significantly decreased by more than 60%, 70%, and 90% at postprandial 6 h, 9 h and 12 h, respectively. The cubic root curve was the most supported model and fitted all PSR data. The cortisol and glucose levels were significantly varied, and the highest values were obtained at postprandial 6 h. Cortisol and the glucose levels then gradually decreased from postprandial 9 h to postprandial 12 h. Intestinal lipase and chymotrypsin activities showed similar results to cortisol, whereas the amylase activity was not significantly different during gastric evacuation. The hypothalamic npy and ore mRNA levels were gradually up-regulated within postprandial 6 h, and then significantly down-regulated from postprandial 9 to postprandial 12 h. By contrast, hepatic lepa and lepb mRNA levels remained high levels within postprandial 6 h and significantly decreased from postprandial 9 to postprandial 12 h. These results indicated that food digestion in the intestine peaked at postprandial 6 h. Afterward, appetite returned and fully recovered at about postprandial 12 h. Therefore, on the basis of the aforementioned results and considering the fish management, postprandial 12 h is the optimal feeding interval of hybrid grouper (Epinephelus moara ♀ × E. lanceolatus ♂). This feeding interval offers potential savings in time and labor spent in cultivating hybrid grouper in captivity. • 90% gastric evacuation of hybrid grouper occurred at postprandial 12 h. • Blood cortisol and glucose peaked at postprandial 6 h and decreased from 9 h to 12 h. • Intestinal lipase and chymotrypsin activity showed the similar results to cortisol. • ore, npy , lepa , lepb showed different expression manners during gastric evacuation. • Postprandial 12 h recommend the optimal feed interval for hybrid grouper. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate performance, biochemical, hematological and tissue parameters in tambaqui Colossoma macropomum juveniles with initial average weight of 18.0 ± 4.0 g submitted to feed restriction. Three feeding protocols were tested for 56 days: continuous feeding (control); feeding for six days and feed restriction for one day a week (F6R1); and feeding for five days and restriction for two days a week (F5R2). Growth performance was evaluated as weight (W), feed intake (FI), feed conversion ratio (FCR), specific growth rate (SGR) and protein efficiency ratio (PER) at 28 days and from 29 to 56 days of experiment. Blood samples were collected at 28 days (after restriction period in F5R2 and F6R1) and before (at 54 days) and after feed restriction period (at 56 days) to determine hematocrit, hemoglobin, plasma glucose, triglycerides, cholesterol and protein levels. Liver and muscle lipid concentrations, the hepatosomatic index and the mesenteric fat index were evaluated after 28 and 56 days. After 28 days there was a decrease in W, FI and SGR and a better FCR for F5R2, when compared to the control. From day 29 to day 56 there was a decrease in W, FI and a better FCR for F5R2, when compared to the control, while SGR and PER of restricted groups were similar to the control. After 28 days there was a decrease in hematocrit and triglycerides for F5R2, while there was no significant difference in hemoglobin, glucose, cholesterol and protein. Hematocrit was significantly lower in F5R2 group, while there was no treatment, period (54 and 56 days) and interaction between them for hemoglobin concentrations. For glucose, there was an effect of the treatment, as well as an effect of the period but there was no interaction between them. For triglycerides levels there was an effect of treatment, period and interaction between them. Protein and cholesterol levels were influenced only by period and both variables showed an increase in their levels at 56 days, compared to 54 days. After 28 days there was no significant difference for liver lipid levels, muscle lipid and the mesenteric fat index in all treatments; however, there was a decrease in the hepatosomatic index in F5R2. After 56 days there was a decrease in liver lipid levels and the hepatosomatic index with the increase in the restriction period, but there was no significant difference for muscle lipid levels and the mesenteric fat index. Juveniles of C. macropomum submitted to feed restriction for one day a week (F6R1), maintained their body reserves and hematological and biochemistry variables (except for triglycerides at 56 days) unchanged and showed good performance, similar to animals continuously fed for 56 days. However, due to the great heterogeneity of the animals, obtained mainly at the end of the experimental period (56 days), it is recommended to carry out periodic weight classifications for the production of this species in RAS. • Recirculating aquaculture system is efficient for C. macropomum production subjected to one day of feed restriction per week. • One day of feed restriction per week showed good growth performance in C. macropomum. • Juveniles of C. macropomum subjected to one feed restriction day a week maintained their body reserves. [ABSTRACT FROM AUTHOR]

Tiger puffer (Takifugu rubripes) is one of the most commercially important fish species cultivated and consumed in East Asian countries, including Japan, South Korea and China. In this study, the hepatic glycolysis, and lipogenesis, and serum biochemistry of tiger puffers subjected to short-term culture in offshore sea cage aquaculture system (OSCS) and recirculating aquaculture system (RAS) were evaluated. Results showed that the activity of hepatic phosphofructokinase, and lipoprotein lipase, ATP level, and serum cortisol content of the male tiger puffers reared in OSCS were significantly higher than those of female tiger puffers reared in OSCS and those of fish reared in RAS. The lowest hepatic fatty acid synthetase activity, lipid droplet number, serum aspartate aminotransferase activity, Na+ and Cl− concentrations were observed in male tiger puffers reared in OSCS. However, serum glucose, triglyceride, total cholesterol, K+ concentrations and alanine aminotransferase activity of tiger puffers reared in RAS and OSCS showed no significant differences. Hepatic glycolysis and lipogenesis were profoundly affected by rearing system and gender. The interaction effect of gender and rearing system on hepatic lipoprotein lipase activity, lipid droplet number and serum Na+ level was observed. These results indicate male tiger puffers exhibited different metabolic status in hepatic glycolysis, lipogenesis, and serum biochemical parameters when reared under two different culture systems. These findings will provide important information for improving tiger puffer (Takifugu rubripes) farming and profitable production using the RAS and OSCS aquaculture systems in the north coast of China. • Male fish glycolysis-limited enzymes activity in the OSCS were higher than RAS. • Male fish lipogenesis-related enzymes activity in the OSCS different from RAS. • Hepatic lipid droplets number of male fish in the OSCS obtained the lowest values. • Serum biochemical indices of fish in the OSCS significantly different from RAS. • Interaction of gender and rearing system cause above difference in tiger puffer. [ABSTRACT FROM AUTHOR]

This study investigated the possible effects of using Pediococcus pentosaceus in common carp (Cyprinus carpio) diet on the growth performance, digestive enzyme activities, haematological indices, and innate immune response s. Four diets were prepared, including a control diet and three diets supplemented with P. pentosaceus at 107, 108, and 109 CFU g−1. After 45 days, fish fed P. pentosaceus at 108 CFU g−1 had significantly higher final body weight, weight gain, and specific growth rate when compared to the control group (P < 0.05). Furthermore, fish fed P. pentosaceus at 108 CFU g−1 had mainly enhanced the digestive enzyme activities, respect to the control fish (P < 0.05). However, the total viable heterotrophic aerobic bacteria were significantly elevated after feeding low dose of P. pentosaceus (P < 0.05). Among haematological parameters, red blood cells (RBCs), white blood cells (WBCs), hemoglobin (Hb), and hematocrit (HCT) were significantly (P < 0.05) increased in fish fed 108, and 109 CFU g−1 of P. pentosaceus. Serum total antibody level, alternative complement, protease, and lysozyme activities, as well as antibacterial activity, were significantly enhanced in fish fed with different doses of P. pentosaceus in comparison with the control group (P < 0.05). The obtained results revealed that P. pentosaceus could be used as a beneficial probiotic to improve the growth performance, digestive enzymes activity, and haemato-immunological responses in common carp culture. • This study investigates the possible effects of using Pediococcus pentosaceus for common carp. • P. pentosaceus significantly improved the growth performance and digestive enzymes activity. • The total viable heterotrophic aerobic bacteria were elevated after feeding P. pentosaceus. • Serum immune responses were significantly enhanced in fish fed with P. pentosaceus. • Also P. pentosaceus enhanced the antibacterial activity against Aeromonas hydrophila in carp. [ABSTRACT FROM AUTHOR]