Growth Performance Of Fish Research Articles

High-efficiency expression of a novel antimicrobial peptide I20 with superior bactericidal ability and biocompatibility in Pichia pastoris and its efficiency enhancement to aquaculture

One of the major constraints on aquaculture is the susceptibility of farmed fish to diseases or slow growing. Antimicrobial peptide I20, as a novel feed additive, is used to cope with these limiting factors. In the current study, the Pichia pastoris expression system was used to produce I20 in large quantities, thereby reducing its application cost. In terms of molecular strategy, the I20 expression codon was optimized according to the preference of P. pastoris codon. Through traditional strategy optimization (expression strain, time, methanol concentration, temperature, and pH), the expression level of I20 in shaking bottles was 21.09 ± 1.10 mg/L. Surprisingly, the expression level of I20 in a 20 L high-cell-density cultivation was 514.78 ± 22.07 mg/L after methanol induction of 72 h. Comprehensive analyses using a series of fluorescence and microscopy revealed that I20 killed bacteria by increasing bacterial membrane permeability and binding bacterial DNA. I20 effectively killed a variety of pathogenic bacteria (Aeromonas hydrophila, Aeromonas veronii, Elizabethkingia miricola, Flavobacterium columnare, Edwardsiella ictaluri, Vibrio parahaemolyticus, Streptococcus agalactiae, Nocardia seriolae, Escherichia coli, and Staphylococcus aureus). I20 was found to have excellent biocompatibility after both feeding and injection studies. Grass carp were fed I20 diet supplemented with 200 mg/Kg I20 for 8 weeks. I20 can effectively promote intestinal villus length, secretion of digestive enzymes, and expression of growth genes to improve growth performance. I20 significantly promotes immune response to reduce tissue damage and bacterial load, enhancing survival after Aeromonas hydrophila infection. In conclusion, we systematically optimized the expression of antimicrobial peptide I20 in P. pastoris, and achieved a satisfactory efficiency for producing antimicrobial peptide I20 by integrating several strategies. The results herein showed that I20-feed promoted growth performance and disease resistance in fish, suggesting a feed supplement with great potential applications for aquaculture.

Docosahexaenoic acid (DHA) promotes grass carp (Ctenopharyngodon idella) muscle fiber development by activating MEK/ERK pathway in vitro and in vivo

Docosahexaenoic acid (DHA) is an essential nutrient for aquatic animals and plays a key role in promoting the growth performance of fish. This study was designed to evaluate the effect of DHA on the development of grass carp muscle fiber in vitro and in vivo. In vitro, myoblasts isolated from grass carp were incubated with 50 μM DHA for 24 h. EDU (5-ethynyl-2′ -deoxyuridine) fluorescence staining showed that 50 μM DHA increased the proportion of EDU-positive cells (P < 0.05). And flow cytometry analysis indicated 50 μM DHA also significantly increased the ratio of S and G2 phase cells and decreased the ratio of G1 phase cells (P < 0.05). In addition, expression analysis of proliferation-related genes further showed that 50 μM DHA promoted the proliferation of myoblasts (P < 0.05). Subsequent transcriptome analysis found that the MEK/ERK signaling pathway was activated during this process. Furthermore, the MEK inhibitor trametinib (Tra) inhibited the proliferative effect of DHA on myoblasts, confirming the causal involvement of this pathway. In vivo, 270 fish (initial weight: 27.92 ± 0.02 g) were randomly fed one of the 3 diets for 8 weeks (each diet had 3 replicates): control diet (Con), 1% DHA diet (1% DHA) and the diet supplement with both 1% DHA and 50 mg/kg trametinib (DHA + Tra). The final body weight, specific growth rate, and protein efficiency were significantly increased in the 1% DHA group (P < 0.05). No significant differences were found in crude protein, ash, crude lipid, and moisture levels of the whole body among the 3 groups, whereas the crude protein content in muscle was significantly increased in the 1% DHA group (P < 0.05), suggesting that the increase of FBW was due to muscle growth. Importantly, the fiber density and sarcomere lengths in the 1% DHA group was significantly higher than those of the control and 1% DHA + Tra groups (P < 0.05). The principal component analysis (PCA) on muscle amino acid and fatty acid well separated the DHA group from the control group, and the total weight rank of the muscle amino acid in DHA group appeared to be optimal. The mRNA expression of MEK, ERK and genes related to muscle development significantly increased in the 1% DHA group compared to the control and 1% DHA + Tra groups (P < 0.05). Similarly, the protein expression of myosin heavy chain (MyHc), myoblast determination protein (Myod) and myogenin (Myog) significantly increased in the 1% DHA group. Together, these results suggest that DHA promotes the muscle fiber development likely via the activation of MEK/ERK pathway in grass carp.

Genetically superior European sea bass (Dicentrarchus labrax) and nutritional innovations: Effects of functional feeds on fish immune response, disease resistance, and gut microbiota

The objective of this study was to determine if selected fish genotypes could benefit from the use of functional additives in novel aqua feed formulations to improve growth performance, gut microbiota, immune response, and disease resistance in fish. Two batches of juvenile European sea bass selected for high growth (HG; selected sires x selected dams), and wild types (WT; wild sires x selected females) were fed a “future diet” coated with three different functional additives for 12 weeks as follows: (i) 2 weeks with a high dose, followed by (ii) 10 weeks with a low dose. The functional additives tested were a mixture of probiotics (PROB), organic acids (ORG), and phytogens (PHYTO). A pathogen challenge test (Vibrio anguillarum) and a stress condition (overcrowding) were performed after each dose. At the end of the feeding experiment, fish from the HG group performed better than fish from the WT group in terms of body weight, relative growth, SGR, and DGI. The results of the two challenge tests performed after two weeks of high dose and ten weeks of low dose showed a significant effect of diet on fish survival. GALT-associated gene expression analysis revealed an interaction between the genotype and diet for il-1β in the distal gut. Finally, regarding the gut microbiota, discriminant analysis showed no clear separation between fish fed the future diet and those fed the same diet with experimental additives. Nevertheless, the relative abundance of certain taxa varied between experimental groups. For example, fish fed the ORG diet had higher relative abundance of Streptococcus in both genotypes, whereas fish fed the PHYTO diet had higher abundance of Lactobacillales. In contrast, fish fed PROB had lower abundance of Pseudomonas and Acinetobacter.

Effects of dietary fiber on growth, feed efficiency and nutrient utilization of tinfoil barb (Barbonymus schwanenfeldii, Bleeker 1853) fry

An 8-week feeding trial was conducted to determine dietary fiber utilization level in Barbonymus schwanenfeldii fry based on the growth, feed efficiency and nutrient utilization. Intestinal α-amylase activity and liver and intestinal histology were used to evaluate the growth performance of fish. Five isonitrogenous (48% crude protein) and isocaloric (20.1 kJ g⁻¹ gross energy) diets were prepared with different fiber levels (0.9%, 3.18%, 5.97%, 8.34% and 10.73%). Each diet was randomly assigned to triplicate groups of fish (0.557 ± 0.001 g) at 20 fry per 100 L glass aquarium. Results revealed that tinfoil barb fry tolerated 10.73% dietary fiber without compromising their growth. Average daily feed intake and feed conversion ratio linearly decreased with increasing fiber levels (P = 0.02). Protein efficiency had a positive association with dietary fiber levels (P = 0.03). Although whole body protein, ash and fiber contents were not related to dietary fiber levels, energy and lipid content linearly decreased with increased dietary fiber levels (P = 0.03). Retention of dietary protein and carbohydrate positively related to dietary fiber levels (P = 0.03). However, lipid and energy retentions were independent of dietary fiber concentrations. Intestinal α-amylase activity showed a unique association with dietary fiber intake in intestinal bulb (P < 0.0001) and hindgut (P = 0.01). However, irrespective of higher midgut amylase activity, its specific content was independent of dietary fiber levels. Besides, there were not any histopathological signs on the gut and liver of fish fed 0.9–10.73% dietary fiber. Meanwhile, condition factor and viscerosomatic index were independent of dietary fiber. Since feeding 10.73% dietary fiber did not affect the growth performance and nutrient utilization, it was concluded that B. schwanenfeldii fry could tolerate 10.73% crude fiber in their practical diet. However, future studies are warranted to determine maximum tolerability of fiber by the fish using further increase in dietary fiber level.

Effect of fish density on biological production in aquaponics combining lettuce hydroponics and loach aquaculture for controlled ecological life support systems in space

There is a need to develop production technology that effectively uses limited water and other resources to create a stable food supply in space. Aquaponics, which combine hydroponics and aquaculture, is expected to be an efficient system for producing crops and animal proteins. This system sustains the reuse of water and balances nutrient elements between both cultures using dissolved elements in fish excrement for plant growth. To evaluate the effect of fish density on biological production and nitrogen usage efficiency in aquaponics combining lettuce hydroponics and loach aquaculture, we investigated the growth performance of lettuce plants and loach fish. We focused on the balance of nutrient elements, especially nitrogen flow in the system. As a result, we found that lettuce grew in aquaponics with a half-strength standard solution with an optimal combination of the number of plants and fish as well as hydroponics with a standard solution. Increasing the density of loach fish and lettuce plants can increase the total biological production of fish and plants. However, it will be important to control both fish and plant densities to increase nitrogen recovery in aquaponics with a high fish density.

Nanopeptide C[sbnd]I20 remarkably enhances growth performance and disease resistances by improving the mucosal structure, antioxidant capacity, and immunity in mandarin fish (Siniperca chuatsi)

Soybean meal, excessively used in place of fish meal (FM) in aquaculture, has a detrimental impact on fish. In this study, the nanopeptide CI20, which was created by conjugating antimicrobial peptide gcIFN-20H and CMCS, were evaluated the feeding effect in mandarin fish (Siniperca chuatsi). Compared with the control group, 150 mg/kg C-I20-fed fish showed the second highest growth performance with no significant changes in body composition. C-I20-fed fish showed more goblet cells and thicker mucin after feeding. The 150 mg/kg CI20 diet boosted the antioxidant capacity, immunity, and digestive enzymes. After Aeromonas hydrophila and infection spleen and kidney necrosis virus infection, the survival rates in the 150 mg/kg CI20 group were highest. Meanwhile, many tissues in the 150 mg/kg CI20 group had significantly lower pathogen loads than the other groups. Treatment with 150 mg/kg CI20 was effective in increasing antioxidant capacity and immunity. The minimum tissue lesions were observed in the 150 mg/kg CI20 group. The goblet cell number and mucin thickness were significantly increased by CI20 treatment after infection. The study results herein showed that a reasonable dietary concentration of CI20 feed promoted growth performance and disease resistances in fish, suggesting a prospective nano antimicrobial peptide for the aquaculture.

Effect of dietary gamma aminobutyric acid (GABA) modulated the growth performance, immune and antioxidant capacity, digestive enzymes, intestinal histology and gene expression of Nile tilapia (Oreochromisniloticus)

Dietary GABA plays an important role in a variety of physiological functions in animals, but this has been rarely reported in fish. This study investigated the effects of dietary supplementation with GABA on growth, serum antioxidant indicators, digestive enzyme activities, intestinal morphology, and the gene expression of Nile tilapia. Diets containing three different GABA concentrations, 0 (control), 200 mg/kg (GABA200), and 500 mg/kg (GABA500), were fed to Nile tilapia (6.97 ± 0.34 g) for 56 days. The present study found that increasing dietary GABA content could increase the fish growth performance including final body weight, weight gain, specific growth rate, average daily gain, protein efficiency ratio, and feed efficiency compared to the control diet. Interestingly, the feed conversion ratio was improved by dietary GABA supplementation. The antioxidant enzyme activities against ammonia stress of fish fed the GABA diets were significantly higher than the corresponding control group throughout the 96-h ammonia exposure. Moreover, significant increases in digestive enzyme activities including protease, amylase and lipase were found in fish fed the GABA diets. Intestinal morphology analysis revealed increased heights and widths of intestinal villi as well as thickness of the intestinal muscularis in fish fed the GABA diets compared to the control diet. The supplementation of diets with GABA significantly increased the expression level of immune- and growth-related genes. The above results indicate that dietary GABA can modulate the growth, improve their immune response and antioxidant status, gut health and morphology and gene expression of Nile tilapia. Therefore, GABA is a promising feed additive for Nile tilapia aquaculture.

Effects of Dietary Vitamin C on the Growth Performance, Antioxidant Activity and Disease Resistance of Fish: A Review

Vitamin C is an essential micronutrient that cannot be synthesized by fish and must be present in fish diets for proper functioning of the physiological conditions. It is required for the biosynthesis of the collagen which is a pre-requisite for the formation of connective tissue and increases the absorption of iron in fish. It prevents various diseases; it is soluble in water and is easily oxidated by heat, light and metal. Most animals can generate vitamin C in sufficient quantities for normal growth and function, but many fish cannot because they lack the enzyme L-gulonolactone oxidase for its manufacture. Vitamin C facilitates the absorption of iron and is necessary for a maximum rate of immune responses and enables a good response to stressors. This updated review presents a general outline of the possible physiological function of vitamin C for fish, with an emphasis on the information on growth performance, antioxidant activity, immune response and disease prevention of fish as well as the synergistic effects of vitamin C with other micronutrients. The diets supplemented with vitamin C promote the growth performance, improve the structure of the intestinal mucosal epithelium, and have a positive impact on the hematological parameter. The addition of different dietary vitamin C to the basal diets significantly improved the growth performance, antioxidant activity, immune response and disease resistance of fish. vitamin C in the aquaculture, having a solid understanding of the positive functions and mechanisms that vitamin C possesses is of the utmost significance.

Effect of different feed nitrogen on nutrient flow, performance, and productivity in the minapadi system

Cultivation with the minapadi method can increase the availability of nutrients and soil organic matter from the decomposition of feed residues and weeds. This system implements environmentally friendly cultivation and creates a sustainable ecosystem because rice plants use fish waste as a source of nutrients, and fish use weeds and pests in rice as a food source. This study aims to find the best feed formula in the minapadi system based on differences in nitrogen content and to analyze the effect of nitrogen from the artificial feed given on nitrogen flow, performance, and productivity in the minapadi system. Using a randomized block design method with four treatments of different feed doses repeated three times to obtain twelve experimental plot units, feed production using local raw materials that are cheap and easy to obtain, soil quality, water, and growth performance are the parameters observed. The results showed that the soil and water quality at the study site was quite good, so the growth performance of rice plants and fish was also good. The treatment of the feed doses given showed that the feed with the highest nitrogen content, namely 9%, gave the best growth performance for rice plants, while 7% nitrogen content gave the best growth for tilapia. The excessive levels of protein are not suitable for fish. However, they are handy for rice plants in the Minapadi system because nutrients that dissolve in water, nutrients from fish feces and urine, and nutrients that are sedimentation on the soil surface, are utilized by rice plants as a nutrient source.

Zooplankton Abundance and Growth of Carps in Farm-Ponds of Different Agro-Climatic Zones of Karnataka

Availability of planktons / natural fish food plays an important role in getting better growth of fish from farm ponds. Study was carried out to evaluate the zooplankton community and growth performance of Carp fishes in farm ponds of coastal and malnad agro-climatic regions of Karnataka. All the ponds were manured with cowdung and poultry manure @ 2000 kg/ha. for the production of planktons. Catla, Rohu and common carp fingerlings were stocked in all the ponds @ 10,000 nos. /ha in 1:1:1 ratio and fishes were fed with groundnut oil cake and rice bran (in 1:1 ratio) @ 5% of the body weight every day. The water samples from all the ponds were collected and filtered for zooplanktons using nylon bolting cloth (60 µm). The growth of fishes in terms of weight was recorded. The analyzed zooplankton planktons were classified into 5 class’s viz., Rotifera, Protozoa, Copepoda, Cladocera and Ostracod. Among zooplanktons observed, copepod contributed maximum to zooplankton community followed by rotifers, cladocerans and ostracod. In coastal ponds the average maximum number of zooplankton 10,368 Cells/m3 and minimum number of 176 Cells/m3 were observed. In Malnad ponds the average maximum number of zooplankton 21,797 Cells/m3 and minimum number of 1579 Cells/m3 were observed. The average maximum growth of Catla, Rohu and Common carp was observed in coastal ponds were 884.42, 640.1 and 692.27 gms respectively and in Malnad farm ponds 1080.71, 954.19 and 1023.18 gms respectively. Use of cowdung and poultry manure in combination was found useful for getting better growth in farm ponds of both the regions.

Dietary Inclusion of Halobacterium salinarum Modulates Growth Performances and Immune Responses in Farmed Gilthead Seabream (Sparus aurata L.).

The use of natural immunostimulants is considered the most promising alternative to promote fish health, productive performance and quality, increasing the aquaculture profitability, sustainability and social acceptance. The purpose of this study was to evaluate the effect of the integration of a potential probiotic strain, Halobacterium salinarum, belonging to the Archaea domain, in the formulated diets of farmed gilthead seabream (Sparus aurata L.) in terms of growth performances and immunity responses. The experiment was set up to test two different levels of inclusion of the bacteria in the diet: 0.05% (D1) and 0.1% (D2). The effects on fish growth performances; humoral (peroxidase, protease, antiprotease and IgM levels) and cellular immunity parameters (phagocytosis, respiratory burst and myeloperoxidase), along with bactericidal activity, were evaluated after 15 and 30 days of experimental feeding. The obtained results showed that the inclusion of H. salinarum at the highest concentration (D2 0.1%) improved growth performances, bactericidal activity against Vibrio anguillarum and some parameters related both to the humoral and cellular immune response, suggesting exploring other aspects of welfare in view of future supplementations of this probiotic strain in the diet of S. aurata.

Effects of humic acid on nutrient removal efficiency of aquatic duckweed (Lemna minor) and both growth performance, and hemato-biochemical parameters of Nile tilapia (Oreochromis niloticus) cultured in water recirculating system

This study was carried out to evaluate the effects of humic acid (HA) on the nutrient removal efficiencies of aquatic duckweed plant (Lemna minor) from a water recirculating system used to culture Nile tilapia (Oreochromis niloticus) fish for 30 days. The HA was added to water at three concentrations of 0 (Control), 1.5, and 3 mg/L in triplicate. Water quality parameters, growth performance, and some hemato-biochemical parameters of the fish in variable HA concentrations were compared. The total ammonia nitrogen (TAN) and total phosphorous (TP) removal efficiency of L. minor increased with increasing the HA concentration from 0 mg/L to 3 mg/L (p < 0.05). The concentration of nitrate (NO3 −) in the HA-3 mg/L was higher than that in the other groups on days 20 and 30 of the fish cultivation period (p < 0.05). The growth performance of fish improved in the HA-3 mg/L compared to the other groups. The addition of different concentrations of HA to water had no adverse effect on the hematological properties of the Nile tilapia. The plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) levels in the HA-0 mg/L and HA-1.5 mg/L groups were higher than in the HA-3 mg/L (p < 0.05). No significant differences in the plasma glucose and cholesterol levels were observed between the HA-groups (p > 0.05), while the triglyceride level increased in the HA-3 mg/L compared to the control (p < 0.05). These results indicated that adding HA to water could be an effective method to enhance the bioremediation performance of the aquatic duckweed plants as biofilter and thus improve water quality, subsequently, fish growth performance in RASs.

Stimulatory effect of dietary alpha-lipoic acid on growth performance, antioxidant capacity, liver enzymes, immunity and protection of African catfish, Clarias gariepinus (B.), Edwardsiella tarda infection.

Edwardsiella tarda is one of the most common causes of fish diseases that hinder aquaculture. Oxidative stress in farm animals can induce a number of pathological disorders, productionand general animal welfare. The use of exogenous dietary nonenzymatic antioxidants such as alpha-lipoic acid (ALA) can stop a pro-oxidant state and thus appears to have the potential to modulate the immune system and protect fish from bacterial infection. Thus, this study investigates the stimulatory effect of dietary ALA on growth performance, antioxidant capacity, liver enzymes, immunityand protection of African catfish, Clarias gariepinus (B.), against an infection with E. tarda. Five isonitrogenous and isocaloric diets (400 g/kg of crude protein) containing ALA at doses of 0.0 (control), 500, 1000, 1500or 2000 mg/kg diet were served to 300 juveniles of African catfish (mean weight = 8.2 ± 0.2 g) adequately thrice per day for 12 weeks. Thereafter, 0.1 mL of E. tarda (ATCC 15947; 1.0 × 108 CFU/mL) was intraperitoneally injected into 10 fish from each tank and was monitored for 14 days. The results showed that ALA-fortified diets significantly boosted the fish growth, feed consumption and utilizationand feed conversion ratio but no did not affect fish survival rate. The highest final fish weight (g), weight growth (g)and weight gain (%) were all considerably higher in fish fed with ALA-fortified diets (p < 0.05), especially from 1000 to 200 mg/kg ALA than the control group. Also, an enhanced hemato-biochemical, antioxidantand immune indices were noticed in African catfish-fed ALA-enriched diets. In a dose-dependent order, the levels of haematological indices such Ht, Hb, RBCs, WBCsand platelets were markedly increased (p < 0.05). Additionally, fish fed with ALA-based diets showed substantial (p < 0.05) declines in aspartate and alanine aminotransferase values, with the lowest values being found in the 2000 mg/kg diet while control group had highest values. Further, African catfish fed the feed fortified with 2000 mg ALA/kg diet showed the highest levels of lysozyme, respiratory burst, proteasesand esterase activities (p < 0.05). Following exposure of fish to E. tarda infection, a significant reduction in the mortality was obtained in African catfish fed with ALA-based diets, especially from 1500 to 2000 mg ALA/kg diet (3.3%); while fish fed with the control diet had highest mortality (86.7%). Therefore, diets supplemented with ALA evoked fish growth performance, antioxidantsand nonspecific immunity of African catfish. Also, resistance of African catfish to E. Tarda infection were raised when fed ALA-fortified diets at optimum inclusion rate of 1300 mg ALA/kg diet.

Growth and nutritional health of Pterophyllum scalare juveniles: Unleashing the benefits of feeding with Artemia sp. in aquariums

Pterophyllum scalare is a popular ornamental fish species, but current rearing methods result in high mortality, low fertility, disease incidence, and slow growth in aquarium conditions. Research on co-feeding for ornamental fish at the juvenile or adult stage needs to be completed. This study implemented a “snacking” feeding strategy using Artemia sp. to evaluate changes in fish survival rate, growth performance, and enzyme activity related to digestion, antioxidants, and immunity in a recirculating aquaculture system. Two feeding strategies were tested: one group was fed a commercial diet plus Artemia sp. (0.1% of diet) as “snacking,” and another group was fed only the commercial diet as normal. “Snacking” with Artemia sp. enhanced fish’s survival and growth performance, with higher relative weight rate, standard length, and total length than the control group. Specific growth rates for weight, standard length, and total length were also more significant in the supplemented group compared to the control group. The activity of amylase, superoxide dismutase, and glutathione peroxidase was substantially higher in the supplemented group. Adding Artemia sp. as a supplement under a “snacking” feeding strategy to the control diet was beneficial for P. scalare juvenile rearing and can guide managing recirculating farming activities.

The Protective Effect of a Dietary Extract of Mulberry (Morus alba L.) Leaves against a High Stocking Density, Copper and Trichlorfon in Crucian Carp (Carassius auratus).

This study was designed to examine the protective effects of the extract of mulberry (Morus alba L.) leaves (EML) on crucian carp (Carassius auratus) against a high stocking density, Cu exposure and trichlorfon exposure, which adversely impact fish growth performance, feed intake and fish locomotion. High stocking densities decreased the activities of amylase, lipase, trypsin, Na+/K+-ATPase and alkaline phosphatase (AKP), and increased the content of malonaldehyde (MDA) in fish digestive organs, indicating an impairment of the digestive function and a disturbance of the antioxidant status. Cu exposure increased the activities of glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) in fish digestive organs, suggesting the activation of amino acid metabolism. Furthermore, trichlorfon exposure reduced the activities of lactate dehydrogenase (LDH), glutathione reductase (GR), GOT and GPT, and the capacities of the anti-superoxide anion (ASA) and anti-hydroxyl radical (AHR) in fish muscles, indicating a disruption of the bioenergetic homeostasis and antioxidant status. Our present study indicates that dietary EML supplementation relieved the detrimental effects induced by these stressors.

Impact of black soldier fly (Hermetia illucens) fresh meal on the growth performance, digestive enzymes, hematology, and intestinal histology of cork fish (Channa striata)

Impact of black soldier fly (Hermetia illucens) fresh meal on the growth performance, digestive enzymes, hematology, and intestinal histology of cork fish (Channa striata)

Partial and full replacement of dietary fish oil by poultry fat feeds in rainbow trout, Oncorhynchus mykiss

ABSTRACT The study investigated the effects of dietary fish oil replacement by poultry fat on growth performance, fillet quality, and serum enzymatic activities in rainbow trout, Oncorhynchus mykiss. The fish were fed three diets (0%, 50%, and 100% replacement) for 2 months with or without a washout period. No significant effects were observed among treatments on growth performance and viscerosomatic index or on fillet moisture, fat, protein, and ash contents (p > .05). Increased poultry fat led to decrease in ω-3 fatty acids and increase in ω-6 fatty acids and monounsaturated fatty acids. The washout period restored most of the changes in fillet fatty acid profiles and serum enzymatic activity in the fish feed containing poultry fat. In conclusion, replacement of dietary fish oil by poultry fat had no detrimental effects on fish growth performance, but reduced fish fillet ω-3 fatty acids, which can be restored via a washout period.

Effects of elevated temperature and microplastic exposure on growth and predatory performance of a freshwater fish

AbstractFreshwater ecosystems are increasingly exposed to co‐occurring anthropogenic stressors that can alter food web interactions and organismal life histories. We examined the individual and combined effects of climate warming and microplastic pollution on the growth rate and predatory performance of an invasive freshwater fish, the round goby (Neogobius melanostomus). In temperature‐controlled chambers, we exposed 160 juvenile gobies to one of six scenarios over 37 d, combining three environmentally relevant concentrations of microplastics (63–75 μm polyethylene microbeads) with two temperature regimes representing contemporary (18°C) and projected mean summer maxima (26°C) in their current range in the Great Lakes–St. Lawrence River basin. Exposure to elevated temperature reduced the growth and predatory performance of round gobies. Their decline in predatory performance was greatest at the highest microplastic concentration, regardless of temperature. The effects of environmentally relevant microplastic concentrations on the growth and performance of gobies were weaker than the effects of thermal stress. Given that the round goby is an abundant and widely distributed bottom‐dwelling fish in nearshore areas of the Great Lakes–St. Lawrence River basin, its responses to these co‐occurring stressors could have cascading effects on food webs.

Growth performance and fatty acids profile of common carp fed with raw black soldier fly larvae and honey bee drone brood

Abstract The present study aimed to compare the growth performance and liver and muscle fatty acid (FA) profile of juvenile common carp fed with raw black soldier fly (BSFL; Hermetia illucens) and honey bee drone brood (BDB; Apis mellifera), a novel insect in aquaculture, with a commercial carp diet (CCF). After 6 weeks, the weight gain and specific growth rate were significantly higher in fish fed with CCF, followed by the BDB-fed and BSFL-fed fish, with significant differences among groups. The essential FA contents in feeds were disproportionally mirrored in fish livers and muscles, suggesting feed-dependant biosynthesis ability in common carp. In conclusion, the results suggest that dietary FAs affect the muscle FA composition of common carp. Yet, the composition of dietary essential FAs content did not mirror the essential FA content in muscle, confirming the biosynthesis of essential FAs. The BDB appeared to be a viable alternative or supplement to CCF compliant with circular bioeconomy without compromising the FA profile of common carp muscles. Despite the low growth performance of fish fed with BSFL, this diet indicated good nutritional qualities regarding the FA profiles.

Calanus finmarchicus hydrolysate improves growth performance in feeding trial with European sea bass juveniles and increases skeletal muscle growth in cell studies

The world will be dependent on the development of novel feed ingredients from renewable sources to ensure sustainable growth of the aquaculture industry. Zooplankton like Calanus finmarchicus are viable new raw material candidates, as they have optimal nutrient profiles for aquatic animals and may be sustainably harvested in large volumes. In this study, the aim was to investigate if a protein hydrolysate of C. finmarchicus was able to influence the growth performance of fish. The effect of dietary inclusion of hydrolysates was tested in a feeding trial with European sea bass (Dicentrarchus labrax) juveniles, benchmarking calanus hydrolysate (CH) against commercially available hydrolysates. The diet with CH inclusion yielded increased growth, with significantly higher body weight than hydrolysates of sardine and tuna fish at the end of the trial. The observed growth-promoting effects were further examined using an in vitro model with skeletal muscle cells from Atlantic salmon. Through bioactivity experiments with muscle cells grown in media containing CH, low-molecular fractions were found to have the greatest positive effect on proliferation, viability, and expression of muscle-specific genes. Characterization of the most potent fraction revealed an abundance of small peptides, along with amino acids and marine metabolites associated with increased muscle growth.