FOREWORD

1. INTRODUCTION

Feed expenses represent the largest operational cost in intensive aquaculture systems, accounting for over half of total production expenditures. Traditional reliance on fishmeal as the primary protein source faces economic challenges due to rising prices and competition from livestock feed industries. Plant-based ingredients have emerged as viable alternatives, offering cost advantages and greater availability (Cai et al., 2013; Gatlin et al., 2007; Van Vo et al., 2020). However, their incorporation faces limitations, including amino acid deficiencies, antinutritional factors, and reduced feed appeal. Notably, many aquatic species demonstrate greater tolerance for plant-derived proteins compared to land animals (Van Vo et al., 2020).

Among plant-based protein sources, soybean meal has become the predominant choice for animal feed formulations owing to its optimal protein content, balanced amino acid composition, and reliable supply (Trosvik et al., 2012). In aquaculture feed formulations, SBM typically constitutes 20-60% of the total dietary composition, with the exact inclusion level varying according to species-specific nutritional requirements (Junior et al., 2016; Koch et al., 2016). However, its cost significantly raises feed prices because of sustainability and external dependency (Hossain et al., 2012). Therefore, it is necessary to determine alternative, available, and sustainable plant protein sources that do not negatively affect the growth performance of fish. Vegetable protein sources, such as canola, sesame, cottonseed, pea, wheat gluten, and peanut meals, have been used instead of soybean meal in several fish-feeding experiments with positive outcomes (Collins et al., 2013; Dernekbaşı et al., 2021; Guo et al., 2011; Hosseini Shekarabi et al., 2021; Li et al., 2023; Yue & Zhou, 2008; Zhou & Yue, 2010; Kleemann et al., 2011; Ustaoğlu Tırıl & Kerim, 2015; Tunca, 2019; Kumar et al., 2020).

The peanut, Arachis hypogaea L., is the fourth-largest oilseed crop in the world, with approximately 51.5 million tons produced worldwide (USDA, 2024). In addition to being high in fat and protein, peanut meal (PNM) is a good source of iron, calcium, selenium, salt, manganese, phosphorus, potassium, copper, and zinc (Ayoola et al., 2012; Davis & Dean, 2016; Hasan et al., 2013; Jonnala et al., 2006; Sales & Resurreccion, 2010; Zhang et al., 2017). PNMs are becoming increasingly popular as a protein source to replace SBM in animal feeds because of their lower cost per unit of protein than SBM (Batal et al., 2005; Dernekbaşı et al., 2021; Goes et al., 2004;).

This research indicates that while studies have been conducted on the use of PNM in rainbow trout diets (Adelizi et al., 1998; Acar & Türker, 2018; Dernekbaşı et al., 2021), no studies have been conducted to assess the elemental values and biomagnification factor of the fish. In this regard, the study sought to ascertain the impact of PNM used at varying rates in rainbow diets on fish fillets' element and biomagnification values.

2. MATERIAL AND METHOD

Experimental trials were carried out at Sinop University's Faculty of Fisheries Research and Application Center in Sinop (Türkiye). Juvenile rainbow trout (Oncorhynchus mykiss) specimens were sourced from Kuzey Su Ürünleri A.Ş., a commercial aquaculture operation located in Samsun, Turkey. Prior to experimentation, fish underwent a 10-day acclimatization period while being maintained on a commercial diet (Black Sea Feed). Following this adjustment phase, specimens were individually weighed and randomly allocated across 15 fiberglass rearing tanks (300 L capacity each), with stocking densities maintained at 20 fish per experimental unit. All tanks featured continuous flow-through water exchange and supplemental aeration systems.

The 12-week nutritional trial employed a completely randomized design with five dietary treatments; each replicated three times. Juvenile rainbow trout (initial mean weight = 89.73 ± 0.08 g) were stocked in experimental tanks at equal densities. Four isonitrogenous (45% crude protein) and isolipidic (17% crude fat) test diets were formulated with graded peanut meal (PNM) inclusion levels: 0% (control, C), 50% (PNM50), 75% (PNM75), and 100% (PNM100). A fifth treatment group received commercial feed (CF) as an industry reference. Both the CF and C groups served as experimental controls for comparative analysis. All formulated diets were nutritionally balanced to match the proximate composition of the commercial reference feed.

Throughout the 12-week experimental period, fish received hand-fed rations twice daily (09:00 and 15:30 hours) to apparent satiation. Water quality parameters were monitored twice per day using a Thermo Scientific Orion 4 Star multiparameter instrument, recording mean values of:

Temperature: 15.98 ± 0.02°C, Dissolved oxygen: 6.12 ± 0.04 mg/L, and pH: 8.15 ± 0.02. For biological sampling, specimens (n=5 per time point) were humanely euthanized at both the initiation and termination of the trial using clove oil anesthetic at concentrations sufficient to ensure rapid loss of consciousness. All collected tissue samples were immediately flash-frozen and maintained at -80°C in a WiseCryo WUF-D500 ultra-low temperature freezer until subsequent.

All elemental analyses were conducted at SUBITAM (Sinop University Scientific and Technological Research Center) following established protocols. Tissue sample preparation followed EPA Method 200.3 for spectrochemical determination of recoverable elements in biological matrices. Fillet samples underwent microwave-assisted acid digestion (Milestone Systems Start D 260) using Suprapur® grade nitric acid, following the manufacturer's HPR-FO-67 protocol for animal tissues. Quantification of elements was performed using an Agilent Technologies 7700X ICP-MS system operated by an accredited scanning electron microscopy laboratory. The analytical protocol incorporated: Three replicate measurements per sample, Certified reference material (Lobster TORT-2) for quality control, Multi-element calibration standards (Agilent 8500-6940 series), and Continuous internal standard monitoring (1 ppm Agilent 5188-6525). Method validation demonstrated: Analytical precision ≤ ±10% RSD, CRM recovery rates of 90-100%, and Results expressed as mean ± standard error.

The biomagnification factor (BMF) is defined as the ratio of the concentration of a given element in fish tissue to its concentration in the fish’s diet. In this study, BMF was calculated using the following equation (Kelly et al., 2008; Majid et al., 2019)

BMF=𝐶_fish/𝐶_diet

where 𝐶_fishrepresents the concentration of an element in the fillets of rainbow trout exhibiting different reproductive characteristics, and 𝐶_dietdenotes the concentration of the same elements in the administered diet

Data processing utilized IBM SPSS Statistics 21 software. Normal distribution was verified using Anderson-Darling tests, while group variance homogeneity was assessed with Levene's test. Intergroup differences were determined through one-way ANOVA with appropriate post-hoc testing.

3. RESULTS

Table 1 shows the live weight initially and at the end of the 12-week study. The control (C) group attained the best weight at the end of the trial. While no statistical difference was observed between the final weights of the groups administered peanut-containing diets (PNM50, PNM75, PNM100) (p>0.05), there was a significant difference between the live weights of the commercial feed (CF) and C groups (p<0.05).

Table 2: The selected element values in the experimental diets (mg/kg)

*Diets (mg/kg)*	Experimental groups
*Diets (mg/kg)*	CF	C	PNM₅₀	PNM₇₅	PNM₁₀₀
Calcium (Ca)	63847.27±1018.21^d	14638.72±39.86^a	19634.98±152.64^b	18367.75±186.89^b	24930.56±127.94^c
Iron (Fe)	585.21±4.48^b	208.36±1.36^a	880.39±0.52^c	1187.43±7.49^d	1460.21±12.45^e
Potassium (K)	26043.13±337.70^a	30958.28±121.36^c	29237.77±196.84^c	27452.13±197.10^b	27943.45±147.26^b
Magnesium (Mg)	6033.03±123.46^b	5781.58±35.76^a	6430.50±34.54^c	6850.06±60.39^d	7150.61±36.19^e
Sodium (Na)	13974.22±224.56^c	4474.52±16.77^a	9944.33±68.67^b	10494.38±113.74^b	17935.96±118.42^d
Phosphorus (P)	41249.02±727.44^d	19392.83±2.10^a	20917.33±176.87^b	19784.59±224.29^a	23406.57±99.17^c
Manganese (Mn)	103.67±0.56^b	93.50±0.84^a	102.89±0.65^b	114.47±0.30^d	107.44±0.20^c
Zinc (Zn)	265.16±2.12^a	329.14±2.58^c	303.37±0.51^b	333.11±0.90^d	372.74±1.27^e
Selenium (Se)	2.31±0.08^d	1.93±0.05^b	1.76±0.06^a	1.79±0.05^a	2.14±0.12^c
Copper (Cu)	24.02±0.17^a	29.25±0.14^b	32.81±0.10^c	38.12±0.18^e	35.32±0.13^d
Ca/P	1.55	0.75	0.85	0.66	0.96

Each value means mean±standard error. Values expressed with different exponential letters on the same line are statistically different from each other (p<0.05).

Figure 1: Selected element values determined in the fillets of the experimental groups (mg/kg)

Figure 2 depicts the biomagnification factor (BMF) of selected elements in the fillets of rainbow trout after the 12-week experimental period. The BMF of K, Mg, Mn, and Cu elements was to be high in rainbow trout fillets given commercial feed (CF group) at the end of the study. The BMF of Se, Fe, Ca, and Na were high in rainbow trout fillets given to the C group. The fillets in the group-fed feed containing 75% peanut meal (PNM₇₅)had a high BMF of the P element.

4. DIscussIon

This study determined selected element values and biomagnification factors in fillets of rainbow trout fed with feeds containing different amounts of peanut meal (50, 75, and 100%) instead of soybean meal. Rainbow trout with initial weights of 89.68±0.05 g reached the highest value with 274.90±9.52g in the control group (C) after 90 days, followed by the PNM₁₀₀ group with 268.37±21.03g. The final weight of the group fed with commercial feed (CF) was 261.42±20.57g. In the study, using peanut meal instead of soybean meal did not have an adverse effect on fish weights. Since the subject of the study was fillet element values and biomagnification values, no discussion was made on growth performances.

Table 2 lists the selected element values of the diets used in the research. The results showed that the element contents in the diets used were different. These differences can be attributed to the differences in the raw materials in both the commercial and experimental feeds. Ca, P, and Se were more dominant in the commercial diet mixtures studied. The progressive incorporation of peanut meal (PNM) in formulated feeds demonstrated a corresponding elevation in calcium (Ca), iron (Fe), magnesium (Mg), and sodium (Na) concentrations. Current findings align with established nutritional benchmarks, where Watanabe (1988) and Goddard (1995) identified optimal dietary mineral requirements for rainbow trout as 30 mg/kg Fe, 3 mg/kg Cu, 13 mg/kg Mn, and 30 mg/kg Zn. However, commercial aquaculture practices often exceed these recommendations, as evidenced by Tacon and De Silva's (1983) documentation of European salmonid diets containing 80-540 mg/kg Fe, 35-100 mg/kg Mn, 5-40 mg/kg Cu, and 50-260 mg/kg Zn - representing 2-11 fold increases above standard requirements. More recent analyses by Sissener et al. (2013) further confirm this variability, reporting typical dietary ranges of 65-493 mg/kg Fe, 2.5-21 mg/kg Cu, 36-330 mg/kg Zn, 4.4-226 mg/kg Mn, and 0.39-4.1 mg/kg Se. These micronutrients play indispensable roles in biological systems, supporting critical physiological processes including growth performance, reproductive success, and metabolic regulation across aquatic species (Fallah et al., 2011; Roy & Lall, 2006; Yıldız et al., 2008;). Analytical evaluation confirms that the mineral profiles of the experimental diets in this investigation satisfy the essential nutritional requirements for rainbow trout cultivation.

Compared to proteins, lipids, and carbohydrates, research on elemental nutrition in fish remains limited, primarily due to the complex interactions between dietary intake and environmental uptake (Antony Jesu Prabhu et al., 2016). Like all organisms, fish require essential elements for critical physiological functions, but unlike terrestrial animals, they can absorb minerals directly from water—except for elements like phosphorus and iodine, which are often present in insufficient concentrations (Kaushik & Lall, 2021). For rainbow trout, established dietary requirements include: Macroelements: Phosphorus (0.07%), magnesium (0.05%). Trace elements: Copper (5 mg/kg), manganese (10 mg/kg), selenium (0.15 mg/kg), zinc (37 mg/kg) (NRC, 2012). Even when elements are present in culture water, studies suggest that dietary supplementation remains crucial for certain minerals, such as calcium, to prevent deficiencies (Vielma et al., 1998). Additionally, metabolic demands may necessitate higher selenium intake than growth requirements alone, as this element supports enzyme function (Fontagné-Dicharry et al., 2015). Traditionally, fishmeal-rich diets provided sufficient minerals, reducing the need for supplementation (Kamalam et al., 2020). However, as fishmeal inclusion decreases in modern aquafeeds, ensuring adequate dietary supply of both macro- and trace elements—with consideration for bioavailability—has become increasingly important (Antony Jesu Prabhu et al., 2016). This research examined the concentrations of Fe, Mn, Ca, Cu, Mg, P, Zn, K, Na, and Se in rainbow trout fillets to assess: Elemental utilization efficiency from diets with varying peanut meal inclusion and Tissue retention patterns to determine storage and metabolic allocation.

Finally, the highest element values, except Cu and Zn, in rainbow trout fillets were obtained from the group fed with commercial feed (CF) (Figure 1). The peanut meal in the diet was increased, and the Na, P, Mg, and K values of fish fillets increased. The Ca, Fe, Mg, Zn, and Cu values of the fillets of the experimental groups were obtained from the groups fed with feed containing 75% peanut meal. The number of studies on fillet element values using different amounts of peanut meal in fish diets is limited. For example, it was reported that using different amounts of peanut flour in feeds affects the elemental values of tilapia fillets (Yılmaz, 2022). Apart from this, Antony Jesu Prabhu et al. (2018) reported that if completely plant-based meals are to be used in rainbow trout diets, mineral supplements should be made to meet the needs of the fish. The current study added the same amount of mineral mix to all experimental diets except the commercial feed (CF). Apart from all these evaluations, the element values of rainbow trout fillets in this study portion weight (250g) were within the ranges reported by USDA (2019).

Selected elements' biomagnification factor values were less than 1 after the 12-week study. When all fillets were evaluated in general, the element with the highest BMF was determined to be K in all groups. Except for the group fed with CF, the BMF value increased as the peanut meal ratio in the trial feeds increased. While no such increase is observed in the K values of the diet (Table 2), it has been determined that there is a parallelism between the K element values in fish fillets (Figure 1) and the BMF of K. Table 2 and Figure 1 demonstrate that the element levels in each of the study experimental diets were higher than those found in fish fillets. Analogous to the current study, Jiang et al. (2016) found that all the elements in the diets they utilized were two to three times higher than in the fillets and that the diets significantly impacted the biomagnification factor measured in fish. According to Varol et al. (2017), variations in the concentrations of certain elements in wild and farmed fish may also be directly related to variations in the amounts of those elements in typical and commercial fish diets. Several studies have shown that the changes in elements used in diet formulation and the addition of varied percentages of mineral premix to diet mixes result in differences in the amounts of elements in commercial feeds (Dadar et al., 2016; Kaya Öztürk, 2022; Kaya Öztürk, 2023 ; Majlesi et al., 2019). The finding that rainbow trout fed varying quantities of PNM had Biomagnification factor values <1 is significant when analyzed in terms of selected elements.

CONCLUSION

This study is the first to evaluate the elemental composition and biomagnification factors in the fillets of rainbow trout fed diets containing peanut meal (PNM) as a replacement for soybean meal. The results showed a parallel relationship between the dietary inclusion level of PNM and the biomagnification values of various elements. In conclusion, substituting soybean meal with PNM in rainbow trout diets did not significantly affect the elemental concentrations in the fillets.

Acknowledgments:

This study was carried out in parallel with the project no SUF-1901-21-010, 2022, supported by the Sinop University Scientific Research Coordination Unit.

Ethical statement:

This study was conducted in compliance with the rules for animal experiments for scientific purposes, and permission was given by the Sinop University, Animal Experiments Local Ethics Committee with permission No. 2020/02 on February 17th, 2020.

Author Contributions:

All authors have reviewed the final version to be published and agreed to be accountable for all aspects of the work.

Concept and design: Dilara Kaya Öztürk, Seval Dernekbaşı, İsmihan Karayücel, Keriman Yürüten Özdemir.

Acquisition, analysis, or interpretation of data: Dilara Kaya Öztürk, Seval Dernekbaşı.

Drafting of the manuscript: Dilara Kaya Öztürk

REFERENCES

Abbas, M. M. M., Shehata, S. M., Talab, A. S., & Mohamed, M. H. (2021). Effect of traditional processing methods on the cultivated fish species, Egypt. Part I. Mineral and heavy metal concentrations. Biological Trace Element Research, 200:2391–2405 DOI: 10.1007/s12011-021-02840-w

Acar, Ü., & Türker, A. (2018). The effects of using peanut meal in rainbow trout (Oncorhynchus mykiss) diets on the growth performance and some blood parameters. Aquaculture Studies, 18(2), 5-13. DOI: 10.4194/2618-6381-v18_2_02

Adelizi, P. D., Rosati, R. R., Warner, K., Wu, Y. V., Muench, T.R., Whıte, M.R. & Brown, P. B. (1998). Evaluation of fish‐meal free diets for rainbow trout, Oncorhynchus mykiss. Aquaculture Nutrition, 4(4), 255-262. DOI: 10.1046/j.1365-2095.1998.00077.x

Antony Jesu Prabhu, P., Schrama, J. W., & Kaushik, S. J. (2016). Mineral requirements of fish: a systematic review. Reviews in Aquaculture, 8(2), 172-219. DOI: 10.1111/raq.12090

Antony Jesu Prabhu, P., Schrama, J. W., Fontagné‐Dicharry, S., Mariojouls, C., Surget, A., Bueno, M., ... & Kaushik, S. J. (2018). Evaluating dietary supply of microminerals as a premix in a complete plant ingredient‐based diet to juvenile rainbow trout (Oncorhynchus mykiss). Aquaculture Nutrition, 24(1), 539-547. DOI: 10.1111/anu.12586

Ayoola, P. B., Adeyeye, A., & Onawumi, O. O. (2012). Chemical evaluation of food value of groundnut (Arachi hypogaea) seeds. American Journal of Food And Nutrition, 2(3), 55-57. 7, DOI: 10.5251/ajfn.2012.2.3.55.57

Batal, A., Dale, N., & Café, M. (2005). Nutrient composition of peanut meal. Journal of applied poultry research, 14(2), 254-257. DOI: 10.1093/japr/14.2.254

Cai, C., Song, L., Wang, Y., Wu, P., Ye, Y., Zhang, Z., & Yang, C. (2013). Assessment of the feasibility of including high levels of rapeseed meal and peanut meal in diets of juvenile crucian carp (Carassius auratus gibelio♀× Cyprinus carpio♂): Growth, immunity, intestinal morphology, and microflora. Aquaculture, 410, 203-215. DOI: 10.1016/j.aquaculture.2013.07.006

Chen, Y. C., Tou, J. C., & Jaczynski, J. (2007). Amino acid, fatty acid, and mineral profiles of materials recovered from rainbow trout (Oncorhynchus mykiss) processing by‐products using isoelectric solubilization/precipitation. Journal of food science, 72(9), 527-535. DOI: 10.1111/j.1750-3841.2007.00522.x.

Collins, S. A., Øverland, M., Skrede, A., & Drew, M. D. (2013). Effect of plant protein sources on growth rate in salmonids: Meta-analysis of dietary inclusion of soybean, pea and canola/rapeseed meals and protein concentrates. Aquaculture, 400, 85-100. DOI: 10.1016/j.aquaculture.2013.03.006

Dadar, M.; Adel, M.; Ferrante, M.; Nasrollahzadeh Saravi, H.; Copat, C.; Oliveri Conti, G. Potential Risk Assessment of Trace Metals Accumulation in Food, Water and Edible Tissue of Rainbow Trout (Oncorhynchus mykiss) Farmed in Haraz River, Northern Iran. Toxin Reviews 2016, 35(3–4), 141– 146. DOI: 10.1080/15569543.2016.1217023.

Davis, J. P., & Dean, L. L. (2016). Peanut composition, flavor and nutrition. In Peanuts (pp. 289-345). Editor(s): H. Thomas Stalker, Richard F. Wilson AOCS Press,

Dernekbaşı, S., Öztürk, D. K., & Karayücel, İ. (2021). The Effects of Using Peanut Meal (Arachis hypogaea L.) Instead of Soybean Meal in Rainbow Trout (Oncorhynchus mykiss Walbaum, 1792) Feeds on Growth, Biochemical Composition and Fillet Color. Journal of Anatolian Environmental and Animal Sciences, 6(1), 135-141. DOI: 10.35229/jaes.854972

European Food Safety Authority (EFSA). (2017). Dietary reference values for nutrients summary report (Vol. 14, No. 12, p. e15121E). DOI: 10.2903/sp.efsa.2017.

Fallah, A. A., Saei-Dehkordi, S. S., Nematollahi, A., & Jafari, T. (2011). Comparative study of heavy metal and trace element accumulation in edible tissues of farmed and wild rainbow trout (Oncorhynchus mykiss) using ICP-OES technique. Microchemical Journal, 98(2), 275-279. DOI: 10.1016/j.microc.2011.02.007

Fontagné-Dicharry, S., Godin, S., Liu, H., Prabhu, P. A. J., Bouyssiere, B., Bueno, M., ... & Kaushik, S. J. (2015). Influence of the forms and levels of dietary selenium on antioxidant status and oxidative stress-related parameters in rainbow trout (Oncorhynchus mykiss) fry. British journal of nutrition, 113(12), 1876-1887. DOI: 10.1017/S0007114515001300

Gatlin III, D. M., Barrows, F. T., Brown, P., Dabrowski, K., Gaylord, T. G., Hardy, R. W., ... & Wurtele, E. (2007). Expanding the utilization of sustainable plant products in aquafeeds: a review. Aquaculture research, 38(6), 551-579. DOI: 10.1111/j.1365-2109.2007.01704.x

Goddard, S. (1995). Feed management in intensive aquaculture. Springer Science & Business Media. p. 194.

Goes, R. H. D. T., Mancio, A. B., Valadares Filho, S. D. C., & Lana, R. D. P. (2004). Degradação ruminal da matéria seca e proteína bruta, de alimentos concentrados utilizados como suplementos para novilhos. Ciência e Agrotecnologia, 28, 167-173. DOI: 10.1590/S1413-70542004000100022

Guo, Y. X., Dong, X. H., Tan, B. P., Chi, S. Y., Yang, Q. H., Chen, G., & Zhang, L. (2011). Partial replacement of soybean meal by sesame meal in diets of juvenile Nile tilapia, Oreochromis niloticus L. Aquaculture Research, 42(9), 1298-1307. DOI: 10.1111/j.1365-2109.2010.02718.x

Hardy, R. W. (2010). Utilization of plant proteins in fish diets: effects of global demand and supplies of fishmeal. Aquaculture research, 41(5), 770-776. DOI: 10.1111/j.1365-2109.2009.02349.x

Hasan M M, Cha M, Bajpai V K & Baek K H (2013). Production of a major stilbene phytoalexin, resveratrol in peanut (Arachis hypogaea) and peanut products: A mini review. Reviews in Environmental Science and Biotechnology 12, 209-221. DOI:10.1007/s11157-012-9294-7

Hossain, M. A., Sultana, Z., Kibria, A. S. M., & Azimuddin, K. M. (2012). Optimum dietary protein requirement of a Thai strain of climbing perch, Anabas testudineus (Bloch, 1792) fry. Turkish Journal of Fisheries and Aquatic Sciences, 12(2), 217-224 DOI: 10.4194/1303-2712-v12_1_04

Hosseini Shekarabi, S. P., Shamsaie Mehrgan, M., Banavreh, A., & Foroudi, F. (2021). Partial replacement of fishmeal with corn protein concentrate in diets for rainbow trout (Oncorhynchus mykiss): Effects on growth performance, physiometabolic responses, and fillet quality. Aquaculture Research, 52(1), 249-259. DOI: 10.1111/are.14887

Jiang, H., Qin, D., Mou, Z., Zhao, J., Tang, S., Wu, S., & Gao, L. (2016). Trace elements in farmed fish (Cyprinus carpio, Ctenopharyngodon idella and Oncorhynchus mykiss) from Beijing: implication from feed. Food Additives & Contaminants: Part B, 9(2), 132-141. DOI: 10.1080/19393210.2016.1152597.

Jonnala, R. S., Dunford, N. T., & Chenault, K. (2005). Nutritional composition of genetically modified peanut varieties. Journal of Food Science, 70(4), 254-256. DOI: 10.1111/j.1365-2621.2005.tb07198.x

Junior, A. C. F., de Carvalho, P. L. P. F., Pezzato, L. E., Koch, J. F. A., Teixeira, C. P., Cintra, F. T., ... & Barros, M. M. (2016). The effect of digestible protein to digestible energy ratio and choline supplementation on growth, hematological parameters, liver steatosis and size-sorting stress response in Nile tilapia under field condition. Aquaculture, 456, 83-93. DOI: 10.1016/j.aquaculture.2016.02.001

Kaliniak, A., Florek,M., Skałecki, P., (2015) Profile of fatty acids in meat, roe, and liver of fish, Zywn. Nauka Technol. Jak. 2 29–46 http://www.pttz.org/zyw/wyd/czas/2015,%202(99)/03_Kaliniak.pdf. (Accessed 29.11.2023),

Kamalam, B. S., Rajesh, M., & Kaushik, S. (2020). Nutrition and Feeding of Rainbow Trout (Oncorhynchus mykiss). In Fish nutrition and its relevance to human health (pp. 299-332). CRC Press.

Kaya Öztürk D. (2022) Element Concentrations of Cultured Fish in The Black Sea: Selenium-Mercury Balance and The Risk Assessments for Consumer Health. Environmental Science and Pollution Research, 29(58), 87998–88007. DOI: 10.1007/s11356-022-21914-3

Kaya Öztürk, D. (2023) Element concentrations of large rainbow trout (Oncorhynchus mykiss) in the Black Sea: selenium-mercury balance and therisk assessments for consumer health, Spectroscopy Letters, 56(6), 343-352 DOI: 10.1080/00387010.2023.2221327

Kelly, B. C., Ikonomou, M. G., Higgs, D. A., Oakes, J., & Dubetz, C. (2008). Mercury and other trace elements in farmed and wild salmon from British Columbia, Canada. Environmental Toxicology and Chemistry, 27(6), 1361-1370.

Kleemann, G. K., Silva, M. D. P., Pezzato, L. E., Teixeira, C. P., Padovani, C. R., & Barros, M. M. (2011). Farelo de algodão como sucedâneo do farelo de soja em rações para tilápia do Nilo. Revista Brasileira de Saúde e Produção Animal, 805-818.

Koch, J. F., Rawles, S. D., Webster, C. D., Cummins, V., Kobayashi, Y., Thompson, K. R., ... & Hyde, N. M. (2016). Optimizing fish meal-free commercial diets for Nile tilapia, Oreochromis niloticus. Aquaculture, 452, 357-366. DOI: 10.1016/j.aquaculture.2015.11.017

Kumar, V., Lee, S., Cleveland, B. M., Romano, N., Lalgudi, R. S., Benito, M. R., ... & Hardy, R. W. (2020). Comparative evaluation of processed soybean meal (EnzoMealTM) vs. regular soybean meal as a fishmeal replacement in diets of rainbow trout (Oncorhynchus mykiss): Effects on growth performance and growth-related genes. Aquaculture, 516, 734652. DOI: 10.1016/j.aquaculture.2019.734652

Lall, S. P., & Kaushik, S. J. (2021). Nutrition and metabolism of minerals in fish. Animals, 11(09), 2711. DOI: /10.3390/ani11092711

Li, B., Su, L., Sun, Y., Huang, H., Deng, J., & Cao, Z. (2023). Evaluation of Cottonseed Meal as an Alternative to Fish Meal in Diet for Juvenile Asian Red‐Tailed Catfish Hemibagrus wyckioides. Aquaculture Nutrition, 2023(1), 1741724. DOI: 10.1155/2023/1741724

Majid, M., Janmohammad, M., Enayat, B., & Akbartabar, T. M. (2019). Heavy metal content in farmed rainbow trout in relation to aquaculture area and feed pellets. Foods and Raw materials, 7(2), 329-338.

Majlesi, M.; Janmohammad, M.; Enayat, B.; Akbartabar, T.M. Heavy Metal Content in Farmed Rainbow Trout in Relation to Aquaculture Area and Feed Pellets. Foods and Raw Materials 2019, 7(2), 329–338. DOI: 10.21603/2308-4057-2019-2-329-338.

National Research Council (NRC) (2012). Nutrient requirements of fish and shrimp. Aquacult Int 20, 601–602 DOI: 10.1007/s10499-011-9480-6

Rebolé, A., Velasco, S., Rodríguez, M. L., Treviño, J., Alzueta, C., Tejedor, J. L., & Ortiz, L. T. (2015). Nutrient content in the muscle and skin of fillets from farmed rainbow trout (Oncorhynchus mykiss). Food Chemistry, 174, 614-620. DOI: 10.1016/j.foodchem.2014.11.072.

Roy, P. K., & Lall, S. P. (2006). Mineral nutrition of haddock Melanogrammus aeglefinus (L.): a comparison of wild and cultured stock. Journal of Fish Biology, 68(5), 1460-1472. DOI: 10.1111/j.0022-1112.2006.001031.x

Ruxton, C. H. (2011). The benefits of fish consumption. Nutrition Bulletin, 36(1), 6-19. DOI: 10.1111/j.1467-3010.2010.01869.x.

Sales J M & Resurreccion A V A (2010). Phenolic profile, antioxidants, and sensory acceptance of bioactive-enhanced peanuts using ultrasound and UV. Food Chemistry 122(3), 795-803. DOI: 10.1016/j.foodchem.2010.03.058

Shalini, S., Arya, Akshata, R., Chauhan, Salve, 2015. Peanuts as functional food: a review. J. Food Sci. Technol. 53, 31–41. DOI:.1007/s13197-015-2007-9

Sissener, N. H., Julshamn, K., Espe, M., Lunestad, B. T., Hemre, G. I., Waagbø, R., & Måge, A. (2013). Surveillance of selected nutrients, additives and undesirables in commercial N orwegian fish feeds in the years 2000–2010. Aquaculture Nutrition, 19(4), 555-572. DOI: 10.1111/anu.12007

Skałecki, P., Florek, M., Kędzierska-Matysek, M., Poleszak, E., Domaradzki, P., & Kaliniak-Dziura, A. (2020). Mineral and trace element composition of the roe and muscle tissue of farmed rainbow trout (Oncorhynchus mykiss) with respect to nutrient requirements: Elements in rainbow trout products. Journal of Trace Elements in Medicine and Biology, 62, 126619. DOI: 10.1016/j.jtemb.2020.126619

Tacon, A. G. J., & De Silva, S. S. (1983). Mineral composition of some commercial fish feeds available in Europe. Aquaculture, 31(1), 11-20. DOI: /10.1016/0044-8486(83)90253-3

Trosvik, K. A., Rawles, S. D., Thompson, K. R., Metts, L. A., Gannam, A., Twibell, R., & Webster, C. D. (2012). Growth and body composition of Nile tilapia, Oreochromis niloticus, fry fed organic diets containing yeast extract and soybean meal as replacements for fish meal, with and without supplemental lysine and methionine. Journal of the World Aquaculture Society, 43(5), 635-647. DOI: 10.1111/j.1749-7345.2012.00595.x

Tunca, T. (2019). The effects fish meal substitution by pea protein and wheat gluten on sea bass’s (Dicentrarchus labrax Linnaeus, 1758) growth performance and feed efficiency raitos. Izmir Katip Celebi University (Turkey) Master Theses, in Türkiye

Türkmen, M., & Ciminli, C. (2007). Determination of metals in fish and mussel species by inductively coupled plasma-atomic emission spectrometry. Food Chemistry, 103(2), 670-675. DOI: 10.1016/j.foodchem.2006.07.054.

USDA (2019). USDA National Nutrient Database for Standard Reference. https://fdc.nal.usda.gov/fdc-app.html#/food-details/173717/nutrients (Accessed 15/10/2024).

USDA (2024). Foreign Agriculture Service. https://ipad.fas.usda.gov/cropexplorer/cropview/commodityView.aspx?cropid=2221000 (Accessed 08/08/2024).

Ustaoğlu Tiril, S., & Kerim, M. (2015). Evaluation of safflower meal as a protein source in diets of rainbow trout [Oncorhynchus mykiss, Walbaum, 1792)]. Journal of Applied Ichthyology, 31(5), 895-899. DOI: 10.1111/jai.12807

Van Vo, B., Siddik, M. A., Fotedar, R., Chaklader, M. R., Foysal, M. J., & Pham, H. D. (2020). Digestibility and water quality investigations on the processed peanut (Arachis hypogaea) meal fed barramundi (Lates calcarifer) at various inclusion levels. Aquaculture Reports, 18, 100474. DOI: 10.1016/j.aqrep.2020.100474

Varol, M., Kaya, G. K., & Alp, A. (2017). Heavy metal and arsenic concentrations in rainbow trout (Oncorhynchus mykiss) farmed in a dam reservoir on the Firat (Euphrates) River: Risk-based consumption advisories. Science of the Total Environment, 599, 1288-1296. DOI: 10.1016/j.scitotenv.2017.05.052

Vielma, J., Lall, S. P., Koskela, J., Schöner, F. J., & Mattila, P. (1998). Effects of dietary phytase and cholecalciferol on phosphorus bioavailability in rainbow trout (Oncorhynchus mykiss). Aquaculture, 163(3-4), 309-323. DOI: 10.1016/S0044-8486(98)00240-3

Watanabe, T. (1988). Nutrition and growth–In: Intensive Fish Farming (Eds) CJ Shepherd, NR Borage. 174–177

Weichselbaum, E., Coe, S., Buttriss, J., & Stanner, S. (2013). Fish in the diet: A review. Nutrition Bulletin, 38(2), 128-177. DOI: 10.1111/nbu.12021

Yildiz, M., Şener, E., & Timur, M. (2008). Effects of differences in diet and seasonal changes on the fatty acid composition in fillets from farmed and wild sea bream (Sparus aurata L.) and sea bass (Dicentrarchus labrax L.). International journal of food science & technology, 43(5), 853-858. DOI: 10.1111/j.1365-2621.2007.01526.x

Yılmaz, Ö. (2022). The effects of groundnut cake used partially instead of fish meal on development, nutritional profile and some physiological parameters in Nil Tilapias (Oreochromis niloticus, Linnaeus 1758). Cukurova University PhD Thesis

Yue, Y. R., & Zhou, Q. C. (2008). Effect of replacing soybean meal with cottonseed meal on growth, feed utilization, and hematological indexes for juvenile hybrid tilapia, Oreochromis niloticus× O. aureus. Aquaculture, 284(1-4), 185-189. DOI: 10.1016/j.aquaculture.2008.07.030

Zhang Bin, Z. B., Sun LanPing, S. L., Wu YaHua, W. Y., Xu Hui, X. H., & Tu Kang, T. K. (2017). Adsorption kinetics of flavonoids from peanut hull by macroporous resin. China Oils and Fats, 42(3), 122-126.

Zhou, Q. C., & Yue, Y. R. (2010). Effect of replacing soybean meal with canola meal on growth, feed utilization and haematological indices of juvenile hybrid tilapia, Oreochromis niloticus× Oreochromis aureus. Aquaculture Research, 41(7), 982-990. DOI:/j.1365-2109.2009.02381.x

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	CF		C	PNM₅₀	PNM₇₅	PNM₁₀₀
Initial (g)		89.7±0.15^a	89.5±0.12^a	89.7±0.12^a	89.7±0.25^a	89.8±0.24^a
Final (g)		261.42±20.57^c	274.90±9.52^a	265.10±16.83^b	266.74±8.04^b	268.37±21.03^b