The Effects of Sodium Alginate on Quality of Rainbow Trout (Oncorhynchus mykiss) Fillets Stored at 4 ± 2°C

Edible coating is a novel food packaging technology for controlling the growth of spoilage bacteria and chemical changes in ready-to-eat food products. Fresh fish are highly perishable foodstuffs and are very susceptible to spoilage. A sodium alginate coating was used to maintain the quality of rainbow trout fillets in chilled storage over a period of 20 days. Fillet samples were coated with an aqueous solution of 3% sodium alginate and then stored at chilled temperature (4 ± 2°C). The control and coated samples were analyzed periodically (every 5 days) for microbial (aerobic plate count and psychrotrophic count), chemical (total volatile basic nitrogen, thiobarbituric acid, peroxide value), and sensory characteristics. The results indicated that the sodium alginate coating helped protect the quality characteristics of treated fresh fish fillets and prolonged the shelf life during chilled storage of rainbow trout fillets.     

Chitosan Coatings Containing Mentha spicata Essential Oil and Zinc Oxide Nanoparticle for Shelf Life Extension of Rainbow Trout Fillets

ABSTRACT

The objective of the current study was to determine the effects of chitosan (CH) coatings containing Mentha spicata essential oil (MSO; 0.2 and 0.4%) and zinc oxide nanoparticle (ZnO; 0.2 and 0.4%) on chemical (total volatile basic nitrogen (TVB-N), 2-thiobarbituric acid reactive substances (TBARS) and peroxide value (PV)), microbial (total viable count, psychrotrophic count, Pseudomonas spp., and Enterobacteriaceae) and sensory (odor, color, and overall acceptability) properties of raw rainbow trout fillets during 14 days of refrigerated storage. Final microbial population of CH + MSO 0.4% + ZnO 0.4% and CH + MSO 0.4% + ZnO 0.2% retarded approximately 3–5 log CFU/g as compared to control groups (P < 0.05). At the end of storage time in control samples, TVB-N, TBARS, and PV reached 49.3 mg N/100 g, 3.31 mg malonaldehyde/kg, and 2.04 meq peroxide/kg lipid, while the values for the treated samples with MSO (0.2 and 0.4%) in combination with ZnO (0.2 and 0.4%) remained lower than 25 mg N/100 g, 2 mg malonaldehyde/kg, and 1.1 meq peroxide/kg lipid, respectively. The results indicate a potential use of CH coating containing MSO and ZnO as an effective type of antimicrobial packaging to maintain quality of rainbow trout fillets.     

Effect of different plant oils on growth performance,fatty acid composition and flesh quality of rainbow trout (Oncorhynchus mykiss)

This experiment intended to assess the effect of sesame (SO), sunflower (SFO) and linseed (LO) oils on growth performance, fatty acid composition of fillet and liver or flesh quality traits of rainbow trout. Fish fed different four iso‐nitrogenous and iso‐lipidic experimental feeds. The control feed contained only fish oil as the primary lipid source. The fillet eicosapentaenoic acid and docosahexaenoic acid levels were the highest in fish fed control feed. In contrast, the liver eicosapentaenoic acid level was the highest in fish fed LO feed. Fish fed SFO feed had the highest level of total n?6 fatty acids in fillet and liver. Fish fed SO feed had the highest level of 18:1 n?9 fatty acid in fillet and liver. During the 12 days refrigerated storage period at 1°C, thiobarbituric acid (TBA) and pH values gradually increased in all dietary groups. However, trimethylamin nitrogen (TMA‐N) values increased in all dietary groups between days 0 and 9 during the storage period. Generally, pH value in fillets of control group was slightly higher than the other fish groups during 12 days refrigerated storage. Nevertheless, the chemical indicators of spoilage, TBA, TMA‐N and pH values were in the limit of acceptability for human consumption. Results of growth performance and chemical tests in the present study showed that sesame, linseed and sunflower oils could be used in feeds for rainbow trout. Moreover, we concluded that further researches should be carried out on the partial replacement of fish oil by sesame oil in rainbow trout nutrition.     

Effect of Fish Gelatin Coating Enriched with Oregano Essential Oil on the Quality of Refrigerated Rainbow Trout Fillet

ABSTRACT

In the present study, the effect of fish gelatin coating (FG; 4%, w/v) containing oregano (Origanum vulgare L.) essential oil (OEO; 1.2% w/v) on shelf-life extension of rainbow trout (Oncorhynchus mykiss) fillet stored under refrigerated storage (4 ± 1ºC) was investigated. The control and the treated fish samples were analyzed periodically for chemical (pH; total volatile basic nitrogen, TVB-N; peroxide value, PV; thiobarbituric acid, TBA) and microbiological (total viable count, TVC; psychrotrophic count) characteristics. The FG + OEO treatment produced significantly lower (p < 0.05) TVB-N values as compared to control and FG-coated samples after Day 6 and until the end of the storage period. The TBA values remained low and were found to fluctuate during storage. Results showed that TVC exceeded 6 log CFU g^?1 on Day 8 of storage for control and FG-coated samples and Day 12 for samples coated with FG + OEO. The reduction of 1.05 and 0.83 log CFU g^?1 of psychrotrophic counts was achieved by FG + OEO coating in trout fillet (p < 0.05) as compared with control and FG-coated samples, respectively. Therefore, the incorporation of OEO into FG coating may be a promising method of maintaining the storage quality of the rainbow trout fillet stored at refrigerated temperature.     

Assessment of the Antibacterial Effect of Chitosan Coated with Heracleum persicum Oil on Rainbow Trout Quality

Today, due to the rapid spoilage of fish, the use of natural preservatives is a priority over those of synthetic varieties. Also, the natural antimicrobial effects of essential oils can help to increase shelf life. There are very few studies concerning the use of essential oils in this regard. In the present study, the antibacterial effect of chitosan coated with Heracleum persicum oil was investigated on the quality of rainbow trout. The control and the coated fish samples were analyzed periodically by generalized estimating equation (GEE) for total viable count (TVC), psychrophilic bacteria, total volatile base nitrogen (TVB-N), polyunsaturated fatty acids (PUFA), texture, taste, odor, and overall acceptance parameters. The results showed that by increasing the amount of chitosan, TVC, psychrophilic bacteria, and TVB-N decreased while PUFA, texture, taste, odor, and overall acceptance parameters increased.     

The Effect of Sodium Caseinate Coating Incorporated with Zataria moltiflora Essential Oil on the Quality and Shelf Life of Rainbow Trout During Refrigerated Storage

ABSTRACT

In the present study, aqueous solutions of sodium caseinate (SC) 8% (w/w) were provided in the form of four treatments—including SC without any essential oil (EO) as well as SC with 0.25, 0.5, and 1% (v/w) concentrations of Zataria moltiflora EO. Fish samples were treated with aqueous solutions and stored at 4 ± 1°C for 20 days. The control and treated fish samples were analyzed for chemical (total volatile basic nitrogen, pH, thiobarbituric acid, peroxide value), microbiological (total viable count and psychrotrophic count), and sensory analyses every 4 days. Based on results, SC edible coating had no antimicrobial effect but acted like a barrier against the fish flesh contamination. Moreover, incorporating Zataria moltiflora EO with SC edible coating reduces peroxide value and thiobarbituric acid-reactive substances values as well as the chemical and microbiological spoilage of refrigerated ?sh samples. Furthermore, sensory evaluation results showed that the presence of thyme oil improved the sensory quality of the rainbow trout.     

Antimicrobial Activity of Selected Essential Oils on Pseudomonas Species Associated with Spoilage of Fish with Emphasis on Cinnamon Essential Oil

ABSTRACT

Eight plant essential oils (cardamom, cinnamon, clove, eucalyptus, lemongrass, lime, nutmeg and rosemary) were evaluated for their antimicrobial activity against three Pseudomonas species associated with microbial spoilage of refrigerated tilapia. In vitro test of the essential oils, using disc-diffusion method, showed various degrees of antimicrobial activity against the Pseudomonas species. Cinnamon essential oil (CEO) had the highest antimicrobial activity, followed by clove essential oil. The remaining essential oils showed consistently weak activity. The antimicrobial efficiency of CEO against the Pseudomonas species was confirmed by potential minimum inhibitory concentration and minimum bactericidal concentration values, ranging between 0.125 and 0.375 µL/mL and 0.250–0.500 µL/mL, respectively. The anti-Pseudomonas activity of CEO was also tested in fish extract model at refrigeration temperature. The essential oil reduced the Pseudomonas viable count in fish extract but to a lesser extent than when it was applied at the same concentrations in culture medium. The chemical composition of CEO showed that the oil contained 79.1% cinnamaldehyde, which was suggested to be responsible for its antimicrobial activity. These results revealed the potential of CEO as a promising natural antimicrobial agent that could efficiently contribute to the control of spoilage bacteria and retard microbial spoilage of fresh fish.     

Determination of Lipid Peroxidation and Fatty Acid Compositions in the Caviars of Rainbow Trout and Carp

In this study, roes obtained from carp (Cyprinus carpio carpio) that were caught in Keban Dam Lake (Turkey) and cultured rainbow trout (Oncorhynchus mykiss) were processed as caviar, and the products were stored at + 4 C°. Lipid peroxidation and the compositions of fatty acids of these products were assessed during production and storage period. The result of fatty analyses showed that palmitic acid (16:0), stearic acid (18:0), palmitoleic acid (16:1), oleic acid (18:1), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), which are all essential fatty acids, were determined in the caviars of the roes obtained from rainbow trout and carp. According to results of chemical analyses, there were no significant differences in thiobarbituric acid reactive substances (TBARs) between rainbow trout and carp caviars (p > 0.05), but malondialdehyde (MDA) levels were found to be statistically significant (p < 0.01). It can be concluded that caviars obtained from both rainbow trout and carp roes are rich in fatty acids and take a part in a balanced and healthy diet.     

Control of Listeria Monocytogenes and Escherichia coli O157:H7 Inoculated on Fish Fillets Using Alginate Coating Containing Lactoperoxidase System and Zataria multiflora Boiss Essential Oil

The present study was conducted to investigate the inhibitory effect of alginate coating incorporated with Zataria multiflora Boiss essential oil (ZEO) and lactoperoxidase system (LPOS), individually and in combination, in order to control inoculated Listeria monocytogenes and Escherichia coli O₁₅₇:H₇ in rainbow trout fillets during 16days of storage at 4°C. The antibacterial activity of ZEO was evaluated against Listeria monocytogenes and E. coli O₁₅₇:H₇ through determination of minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC). In vivo study was performed by inoculating four strains of L. monocytogenes as culture cocktail and one strain of E. coli O₁₅₇:H₇ on trout fillets for their survival evaluation during the 16-day storage. Results indicated that ZEO and LPOS, when used in combination in alginate solution, had a stronger effect on the control of mentioned bacteria in trout fillets; however, their individual use could significantly inhibit their growth, when compared to the control. Moreover, it has been implicated that alginate coating, when used with no antimicrobial agent, had a supportive effect on the growth of these pathogenic bacteria. Therefore, the application of alginate coating containing ZEO and LPOS is recommended in foods, especially fish and fish products.     

Comparison of NADH-dependent cytochrome b5 reductase activity and in vitro methemoglobin induction by sodium nitrite in Oncorhynchus mykiss, Salmo salar, and Salvelinus fontinalis

Methemoglobin is hemoglobin containing ferric iron. Methemoglobin cannot bind to oxygen and at high concentrations causes tissue hypoxia. Brook trout (Salvelinus fontinalis) develop significantly greater methemoglobinemia than Atlantic salmon (Salmo salar) or rainbow trout (Oncorhynchus mykiss) following general anesthesia with benzocaine or tricaine methanesulfonate. The objective of this study was to compare the activity of the major methemoglobin reducing enzyme, NADH-dependent cytochrome b5 reductase (CB5R), in brook trout erythrocytes to the activity of CB5R in Atlantic salmon and rainbow trout erythrocytes. Methemoglobin levels were compared using co-oximetry following in vitro incubation of erythrocytes with sodium nitrite (NaNO₂). The CB5R activity was measured using a ferricyanide assay. There was significantly greater methemoglobin at time 0 in brook trout erythrocytes than in rainbow trout or Atlantic salmon erythrocytes (2.79 ± 0.29 %, 2.19 ± 0.23 %, 2.08 ± 0.14 %), (P < 0.001). There was significantly greater methemoglobin induction by NaNO₂ in brook trout erythrocytes (33.14 ± 3.32 %) than in rainbow trout or Atlantic salmon erythrocytes (28.73 ± 2.92 % and 24.85 ± 1.40 %, respectively), (P < 0.001). The CB5R activity was significantly less in brook trout erythrocytes (median of 3.05 μmol/min/μl) than in rainbow trout erythrocytes (median of 6.73 μmol/min/μl). The CB5R activity in Atlantic salmon erythrocytes (median 4.09 μmol/min/μl) was not significantly different than in brook or rainbow trout erythrocytes. Total methemoglobin at any one time is a balance between induction by oxidants and reduction by antioxidants. Lower CB5R activity in brook trout erythrocytes may contribute to a species-specific sensitivity to methemoglobin induction; however, there are likely additional factors.     

Effects of Chitosan Coatings Enriched with Different Antioxidants on Preservation of Grass Carp (Ctenopharyngodon idellus) During Cold Storage

To investigate the effects of chitosan composite coatings for maintaining the quality of grass carp portions, indictors of microbiology (total bacteria count, TBC), chemistry (pH; total volatile basic nitrogen, TVB-N; 2-thiobarbituric acid, TBA; K-value), and sensory characteristics were analyzed periodically. The results showed that chitosan (1.5%, w/v) + acetic acid (1.0%, v/v) + tea polyphenol (TP, 0.5%, w/v) coating significantly (p ≤ 0.05) reduced growth of microorganisms as reflected in TBC, lipid oxidation as displayed in TBA, chemical spoilage as reflected in pH, TVB-N, K-value, and sensory characteristic scores compared to the control samples. The effect of chitosan (1.5%, w/v) + acetic acid (1.0%, v/v) + vitamin C (VC, 0.5%, w/v) coating was better than chitosan (1.5%, w/v) + acetic acid (1.0%, v/v) coating. Chitosan together with acetic acid and TP can be used as a type of preservative coating for grass carp portions under chilled storage.     

Determination of growth performance,meat quality and colour attributes of large rainbow trout (Oncorhynchus mykiss) in the southern Black Sea coasts of Turkey

The aim of this study was to determine the growth performance, meat quality and colour attributes of large rainbow trout (Oncorhynchus mykiss) in net cage systems in the southern Black Sea coasts of Turkey. In the study, large rainbow trout with an initial weight of 1,322.07 ± 57.72 g were reached to 3,385.30 ± 140.98 g and the survival rates were 95.69 ± 1.32% in 5‐month production period. Crude protein and crude fat values of fish meat were ranged between 16.75 ± 0.07–20.18 ± 0.90% and 9.22 ± 0.15–12.29 ± 0.42%, respectively (p < .05). The essential and non‐essential amino acid values were between 12.92 ± 0.02–13.09 ± 0.01 g/100 g and 11.97 ± 0.14–11.47 ± 0.01 g/100 g, respectively (p > .05). C20:5n‐3, C22:6n‐3, ?3 and ?6 values in fish meat were between 4.32 ± 0.02–4.30 ± 0.08% (p < .05), 8.31 ± 0.10–7.72 ± 0.15% (p < .05), 13.41 ± 0.10–12.93 ± 0.23% (p < .05) and 21.85 ± 0.06%‐19.74 ± 0.36 (p < .05), respectively. As a result, it can be concluded that large rainbow trout cultured in the southern Black Sea coasts of Turkey is a rich source of food in terms of fatty and amino acid compositions and atherogenicity index, thrombogenicity index and hypocholesterolaemic/hypercholesterolaemic values.     

The Impact of Diets Supplemented with Different Forms of Rosemary and BHA on Chemical,Microbial and Sensory Properties of Rainbow Trout Fillet

The objective of this study was to evaluate the effect of different forms and doses of rosemary on chemical, microbial, and sensory properties of rainbow trout fed nine different diets: control (C), 20 g.kg^?1 rosemary powder (20RP), 40 g.kg^?1 rosemary powder (40RP), 0.3 g.kg^?1 rosemary extract (0.3RE), 0.6 g.kg^?1 rosemary extract (0.6RE), 0.15 g.kg^?1 rosemary nanopowder (0.15RNP), 0.3 g.kg^?1 rosemary nanopowder (0.3RNP), 0.15 g.kg^?1 butylated hydroxyanisole (BHA) (0.15BHA), and 0.3 g.kg^?1 BHA (0.3BHA). After 8 weeks’ feeding, the fish fillets were sampled on the 1st, 4th, 8th, 12th, and 16th days and then stored on 4°C. Lower value of pH, peroxide value (PV), total volatile base nitrogen (TVB-N), free fatty acids (FFA), and thiobarbituric acid (TBA) were reported in fish fed with RP, RE, RNP, and BHA; among them, RNP groups had the lowest properties (p < 0.05). Furthermore, lower total viable aerobic bacterial counts (TVC) and psychotropic counts (PTC) were observed in the fillets of the fish fed with rosemary treatments, especially in RNP treatments (7.52–9.41 log₁₀ CFU.g^?1), along with a slower spoilage in terms of sensory factors (texture, color, odor, and overall) on the 16th day. Finally, use of natural antioxidant nanorosemary in the diet may positively affect fish fillet quality and delay post-mortem deterioration.     

The Effect of Whey Protein Isolate Coating Enriched with Thyme Essential Oils on Trout Quality at Refrigerated Storage (4 ± 2°C)

ABSTRACT

The present study evaluated the effect of whey protein isolate (WPI) coating enriched with thyme essential oil (EO; 3, 5, and 7%, v/v) on whole trout chemical and microbial quality during refrigerated storage at 4 ± 2°C. As a result of this study, the addition of thyme essential oil to WPI coatings enhanced quality significantly better than that of the control and WPI coating without thyme essential oil during refrigerated storage, and this effect increased with an increase in the thyme EO concentration in WPI coating.     

Effects of feed processing method (extrusion and expansion-compression pelleting) on water quality and growth of rainbow trout in a commercial setting

To determine the effects of feed processing method (extrusion or expansion followed by compression pelleting) on feed physicochemical characteristics, fecal stability, water quality, and growth performance in rainbow trout, three types of feed pellets (expanded sinking [EpS], extruded sinking [ExS], extruded floating [ExF]) were prepared, analyzed, and fed to juvenile rainbow trout (initial weight = 285.8 ± 15.2 g) at three feeding rates based on feeding rate curves developed at Snake River Farm (Buhl, Idaho, USA) (median rates [%BW] for feeding rate 1: 0.85; feeding rate 2: 0.95; feeding rate 3: 1.05) for 124 days. Results showed that all feeds had similar chemical composition, but the degree of starch gelatinization (as % of starch) was significantly higher in ExS (90.01 ± 0.26) and ExF (84.82 ± 0.63) than in the EpS (9.09 ± 0.41) feed, which led to extruded feeds having much higher water stability, fecal durability, and lower phosphorus discharge. The ExF feed produced better growth (% increase; 154.4 ± 18.5) and feed conversion (1.06 ± 0.06) compared to EpS (126.3 ± 12.4 and 1.26 ± 0.14) and ExS (121.7 ± 7.8 and 1.22 ± 0.04) in rainbow trout. Growth (% increase) improved as feeding rate increased (feeding rate 1: 125.6 ± 10.3; feeding rate 2: 140.8 ± 16.0), but further improvements were not observed at the highest feeding rate (feeding rate 3: 135.9 ± 22.8). The present study is the first to show that the extrusion process not only produces pellets having better quality than the expansion-compressed pelleting method but also improves fecal size and durability in water, and therefore, use of extruded feeds has the potential to improve waste collection and removal and reduce contribution to pollution in effluent.     

Effect of Chitosan-Gelatin Composite and Bi-Layer Coating Combined with Pomegranate Peel Extract on Quality Properties of Belanger’s Croaker (Johnius Belangerii) Stored in Refrigerator

The aim of this study was to evaluate the effects of chitosan-gelatin coating with two different methods (composite and bi-layer) in combination with pomegranate peel extract (PPE) on the microbiological (mesophilic bacteria, psychrotrophic bacteria, and Enterobacteriaceae) and chemical (total volatile bases-nitrogen (TVB-N), pH, thiobarbituric acid (TBA), and free fatty acid (FFA)) properties of Belanger’s croaker (Johnius belangerii) fillets during refrigerated storage (4 ± 1°C). In this study, composite coating (CC), bilayer coating (BC), CC+PPE, and BC+PPE led to 6.88, 7.00, 6.52, and 6.32 log₁₀ CFU/g reduction in mesophilic bacteria, 6.67, 7.02, 5.35, and 4.21 log₁₀ CFU/g in PTC and 2.99, 2.71, 2.37, and 2.41 log₁₀ CFU/g, compared with control sample for 16 days storage time, respectively. Chitosan-gelatin coating enriched with PPE has retarding effects on spoilage of fish samples, thus extending the shelf life during refrigerated storage. The quality characteristics of croaker treated with chitosan-gelatin coating combined with PPE were better than those treated by chitosan-gelatin coating or PPE alone during the storage, exhibiting that there is a synergistic effect between chitosan-gelatin coating and PPE. The bi-layer coating was better than one composite coating in combination with PPE in reducing lipid oxidation of fillets.     

Production Characteristics of Rainbow Trout,Oncorhynchus mykiss and Brook Trout,Salvelinus fontinalis Under Seasonal Pond Conditions

Abstract

The production characteristics of juvenile rainbow trout, Oncorhynchus mykiss and brook trout, Salvelinus fontinalis were compared under winter pond conditions. Juvenile rainbow trout (55.1 ±1.5 g) and brook trout (28.9 ±0.4 g) were stocked at a density of 8,750 fish/ha into six 0.04-ha ponds. After 163 days, survival, growth, and feed conversion were similar (P >0.05). The results of this study suggest that brook trout may attain growth rates similar to rainbow trout under winter pond conditions in temperate regions of North America.     

Structural and Rheological Characteristics of Alginate from Sargassum cristaefolium Extracted by Twin Screw Extruder

This study aimed to investigate the effects of process extrusion on the characteristics of Sargassum cristaefolium sodium alginate (SCSA) extracted using twin-screw extruder. Box-Behnken Design (BBD) from response surface methodology (RSM) was established to understand the effects of temperature, screw speed, and pH on the multiple-responses of alginate characteristics including intrinsic viscosity, yield, and molecular weight. The results revealed that temperature, screw speed, and pH significantly affected (P < .05) all responses. The optimum extraction condition was found at temperature of 58.18°C, screw speed of 77.99 rpm, and pH 10.11. At this condition, the response of residence time distribution was 7.07 ± 0.029 min, yield of 34.01 ± 0.12%, intrinsic viscosity of 460.13 ± 14.75 mL/g, and molecular weight of 217.94 ± 7.14 × 10³ g/mol. This alginate had mannuronic acid to guluronic acid (M/G) ratio of 0.28, and the L-guluronic acid block was 0.78, which was higher than the D-mannuronic acid block. Rheological characterization of SCSA in aqueous solution was shear-thinning pseudoplastic, and alginate gel in 1 M CaCl₂ was more elastic than liquid.     

Effects of Black Cumin Oil (Nigella sativa) on Sensory,Chemical and Microbiological Properties of Rainbow Trout During 23 Days of Storage at 2 ± 1°C

In the present study, black cumin oil in the rates of 0.00 % (the control), 0.10 %, 0.40 %, 0.70 %, 1.00 % and 1.30% was added to rainbow trout feed for 144 days. After the feeding process, trout were harvested and stored at 2 ± 1°C in ice, and changes in chemical, microbiological, and sensory parameters were examined periodically. According to sensory analyses, black cumin oil used in fish meat did not cause a perceptible sensory change for all groups. Chemical analyses showed that the addition of black cumin oil to fish feed led to higher total volatile basic nitrogen content in the fish flesh. During the storage period, the highest peroxide values were observed in the groups with 1.0% and 1.3% black cumin oil added, and the lowest were in the groups with 0.0% and 0.1% added oil. The highest microbial count value was observed in the control group.     

Effects of Dietary Savory and Myrtle Essential Oils on Growth,Survival, Nutritional Indices,Serum Biochemistry,and Hematology of Farmed Rainbow Trout,Oncorhynchus mykiss,Fry

The effects of diets containing different levels of essential oils from savory Satureja khuzestanica Jamzad and myrtle Myrtus communis L and an immunity complement were investigated on growth, survival, nutritional indices, serum biochemistry, and hematology of farmed rainbow trout, Oncorhynchus mykiss, fry (n = 4500; 5 ± 2 g). The essential oils were dosed as 300 and 500 mg/kg diet. After 60 d, the fish fed 300 mg/kg of the essential oils showed the highest counts of white blood cells (P < 0.05). The same treatment revealed the greatest levels of hematocrit, total protein, and albumin, but glucose and cholesterol values significantly decreased compared with the control (P < 0.05). Feeding fish with 300 mg/kg of the essential oils led to highest records of specific growth rate and survival rate but the lowest feed conversion ratio (FCR), and those fed with immunity complement attained the lowest values of growth parameters. The fry fed with immunity complement and 300 mg/kg of myrtle essential oil achieved the highest and lowest FCR values, respectively. The results indicate that dietary supplementation of 300 mg/kg of the above essential oils exert positive impacts on the growth performance, feeding efficiency, and hematological factors in O. mykiss.