Document Type : Original Article


1 Department of Fisheries, Faculty of Marine Natural resources, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran;

2 Department of Fisheries, Faculty of Marine Natural resources, Khorramshahr University of Marine Science and Technology, Khorramshahr,

3 Coldwater Fishes Genetic and Breeding Research Center, Iranian Fisheries Research Organization, Yasuj, Iran


Aloe vera has been used worldwide in pharmaceutical, food and cosmetic industries due to the plethora of biological activities of its constituents. This study was done to evaluate the effects of dietary aloe vera on growth and lipid peroxidation in rainbow trout (Oncorhynchus mykiss). A total number of 480 O. mykiss (mean weight 9.50 ± 0.85 g) were randomized into four experimental groups including one control and three experimental groups that aloe vera was incorporated in their diet at 0.5, 1.0 and 2.0 g kg-1. Trial was done for eight weeks. Then biometry and blood sampling were done. Plasma malondialdehyde, ferric reducing ability of plasma and growth index were estimated at the end of study. The results showed that aloe vera extract did not affect growth indices. Malondialdehyde was increased in the experimental group compared to the control group but ferric reducing ability of plasma showed a decrease in experimental groups (p < 0.05) compared to the control group. Our findings showed that dietary aloe vera have adverse effects on antioxidant defense system in O. mykiss.




Aloe barbadensis Miller (Aloe vera) is a tropical or subtropical plant characterized by lance-shaped leaves with jagged edges and sharp points that belongs to Liliaceae or Aloeaceae family.1 The leaves are 30 to 50 cm long and 10 cm broad at the base. Color is pea-green, white spotted while young, and has bright yellow tubular flowers, 25 to 35 cm in length arranged in a slender loose spike. It contains a colorless mucilaginous gel called aloe vera gel.2 Several biological effects of aloe vera including immuno-stimulation, increasing growth performance, improvement of wound healing in fish have been reported.3- 5

Reactive oxygen species (ROS) are continually produced in animals during normal aerobic metabolism that can damage most cellular components leading to cell death.6 Fish like other vertebrates possess an antioxidant defense system to reduce the negative effects of ROS. Main enzymes involved in this system are superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), glucose-6-phosphate dehydro-genase (G6PD) and glutathione S-transferase (GST).7 Fish like all aerobic organisms are susceptible to ROS,8 however, most of data about oxidative defense in fish are focused on natural and anthropogenic toxicological aspects especially environmental factors and xenobiotics.9 In different studies effect of different diets on fish antioxidant defense had been assayed.10,11 In vivo antioxidant capacity of organic extracts of aloe vera leaf had been shown.12,13 Therefore, this study was performed to evaluate effects of aloe vera on growth and lipid peroxidation in rainbow trout, Oncorhynchus mykiss.


Materials and Methods


Diets. Basal diet based on formulation of 48.25% protein, 18.86% lipid, 8.23% carbohydrates and 9.36% moisture was prepared (Table 1). Experimental diets were produced adding appropriate amount of aloe vera gel (Barij Essence Pharmaceutical Co., Kashan, Iran) to make experimental diets as follows: 0.5, 1.0 and 2.0 g kg-1 meal, respectively, in groups 1, 2 and 3. Feeds were dried in the oven separately and then were sent to oiling process to be covered with fish oil. In control group aloe vera was not added to basal diet. The composition of the diets is shown in Table 1.


Table 1. Proximate composition of the basal diets fed to Oncorhynchus mykiss.

Diet ingredient


Protein (%)


Fat (%)


Moisture (%)


Ash (%)


Carbohydrate (%)


Energy (KJ kg-1)




Experimental design. A total number of 480 rainbow trout were acclimatized for one week in 300 L aquaria. After this period fish (average body weight of 9.50 ± 0.85 g; average length 9.46 ± 1.10 cm) were randomly divided into 12 aquariums (300 L) each containing 40 fish, arranged in a flow-through system. Each treatment was done in triplicate. The fish were kept for eight weeks in controlled condition (Temperature 11.30 ± 0.80 ˚C, pH = 7.92 ± 0.68 and dissolved oxygen = 7.80 ± 0.48 mg L-1) under natural photoperiod and fed at 3.00% body weight per day spread across the feeding times (08:00 and 15:00). Environmental parameters were controlled daily. The survival was controlled daily. The feeding ration was corrected every two weeks following 24 hr starvation and batch weighing. At the end of experiment all of fish in each tank were individually weighed 24 hr after the last feeding.

Growth Performance. To define the growth indices of the O. mykiss, biometry was done in all groups once every two weeks during the experiment. After eight weeks, all of the fish in experimental groups weighed by digital scale (bearing: 0.01 mg). Specific growth rate (SGR), feed conversion ratio (FCR) and condition factor (CF) were calculated using standard formula.14

Weight Gain (WG) = Wf - Wi

Feed conversion rate (FCR) = Food intake/Weight gain

Condition factor (CF) = Wet body weight × 100 / (Total body length) 3

Specific growth rate (SGR) = 100 × (Ln Wf – Ln Wi)/Days

where, Ln is natural logarithm, Wf is mean final weight (g) and Wi is mean initial weight (g).

Biochemical analysis. The blood samples were taken through the severing the caudal peduncle and stored in heparinized tubes. For biochemical assays, blood samples were centrifuged at 5000 g for 5 min (Model D7200; Hettich, Tuttlingen, Germany) at room temperature immediately then plasma was separated, pooled (4 samples per pool) and stored at – 80 ˚C until analysis. Total protein and albumin were assayed by biuret, and Bromocresol green binding method and globulin were calculated by distracting albumin from total protein.

The total amount of plasma lipid peroxidation was indicated by the content of malondialdehyde (MDA) as described by Buege and Aust.15 Briefly, one volume of plasma was mixed with two volumes of a stock solution of 15.00% w/v trichloroacetic acid, 0.375% w/v thiobarbituric acid and 0.25 molhydrochloric acid thoroughly. The solution was heated for 15 min in boiling water bath. After cooling, the precipitate was removed by centrifugation at 1000 g for 10 min. The absorbance of the clear supernatant was determined at 535 nm.

The FRAP reagent included 10mM 2,4,6-Tri (2-pyridyl)1,3,5-triazine (TPTZ) solution in 40mM HCl, 20 mM FeCl solution and 0.3 M acetate buffer (pH=3.6) in proportions of 1:1:10 (v/v). 50 l of each diluted
ethanolic extracts were mixed with 3 mL of freshly prepared FRAP reagent and the reaction mixtures incubated at 37 ˚C for 30 min. Absorbance at 593 nm was determined against distilled water blank. FRAP values were expressed as µmol of Fe in each mL of plasma.16

Statistical analysis. All data are presented as mean ± SD. The SPSS (Version 13; SPSS Inc., Chicago, USA) was used for analysis. Data were analyzed by one-way ANOVA followed by Tukey’s multiple comparisons test. A p-value less than 0.05 was determined as a significant difference.



No mortalities were recorded during the trial. As seen in Table 2 at the end of feeding period, dietary aloe vera did not affect growth indices in O. mykiss and a significant change was not recorded between control and experimental groups (p > 0.05), (Table 2). Feed conversion rate was 0.01 ± 0.43 in control group and was not affected by dietary aloe vera as a significant change was not recorded in experimental groups compared to control group (p > 0.05). Changes in body condition factor showed a similar result as a significant change was not seen in experimental groups in comparison to control.

Malondialdehyde levels showed variation between experimental groups but was significantly higher in fish fed 2.0 g kg-1 aloe vera (p < 0.05). Plasma MDA content was higher in fish fed with 2 g kg-1 aloe vera compared with those fed with 1.0 g kg-1 aloe vera (p < 0.05), but both of them did not show significant changes compared with group that fed with the lowest dose of aloe vera. Ferric reducing antioxidant was only affected in fish fed with
0.5 g kg-1 aloe vera compared with control as it was decreased significantly (p < 0.05) but in other experimental groups did not show a significant change compared with control group (Table 3). There were no differences between the experimental groups.


Table 2. Growth performance in Oncorhynchus mykiss fed with control diet, 0.5, 1.0 and 2.0 g kg-1 aloe vera for eight weeks. Data are presented as mean ± SD.



Aloe vera concentration in diet (g kg-1)




Initial body weight (g)

0.31 ± 9.53

0.54 ± 9.76

0.10 ± 9.15

0.31 ± 9.47

Final body weight (g)

   0.95 ± 53.63

  1.49 ± 60.82

  4.38 ± 59.03

  3.54 ± 54.02

Weight gain (g)

  1.26 ± 44.09

1.089 ± 51.06

   4.49 ± 49.88

  3.02 ± 44.88

Relative growth rate (%)

0.01 ± 0.44

0.01 ± 0. 50

0.04 ± 0.49

0.01 ± 0.44

Specific growth rate (%)

0.04 ± 6.30

0.06 ± 6.54

0.14 ± 6.49

0.09 ± 6.31

Feed conversion ratio (%)

0.01 ± 0.43

0.05 ± 0.42

0.01 ± 0.44

0.01 ± 0.43

Body condition

0.04 ± 1.47

0.05 ± 1.49

0.05 ± 1.49

0.04 ± 1.54


Table 3. Effect of dietary aloe vera on plasma malondialdehyde concentration and ferric reducing ability of Oncorhynchus mykiss. Data are presented as mean ± SD.



Aloe vera concentration in diet (g kg-1)




Ferric reducing ability (μmolL-1)

747.83 ± 96.83a

 878.80 ± 103.61b

  691.70 ± 91.97ab

  975.01 ± 81.15ab

Malondialdehyde concentration (μmolmL-1)

66.83 ± 3.38a

31.65 ± 5.28ab

52.56 ± 7.63a

25.95 ± 2.81b

ab Different superscripts letters in each row indicate significant difference (p < 0.05).




Although effects of aloe vera on some animals had been studied, there is lack of information about its effect on the antioxidant system of O. mykiss and the other aquatic species. In this study aloe vera did not affect growth parameters in experimental groups. In Amphiophus labiatusfedwith different levels of aloe vera similar results was recorded as a dose dependent response changes in growth parameters was not seen.17 Farahi et al. showed that aloe vera (10 g kg-1 of diet) and Melissa officinalis had no effect on growth performance in O. mykiss.18 Heidarieh et al. demonstrated that high doses of dietary aloe vera had a positive effect on rainbow trout growth performance.5 In Gold fish, Carassius auratus maximum specific growth rate and weight gain was recorded in fish fed with diet containing 0.5 g kg-1 aloe vera.19 Controversial reports on growth promoting effects of aloe vera that also reported for other herbal additives may be caused by different amount of additive, composition of basal diet, management and husbandry conditions.20,21

Antioxidant effects of plants containing compounds such as flavonoids, phenolic compounds, ascorbic acid and tocopherol have been reported.22 The aloe had polysaccharides,23 antioxidant enzymes,24 Phenolic compounds and aloesin derivatives,25 that could be related to effectiveness of aloe as an antioxidant in some reports. In contrast to clinical reports of the useful activity with aloe gel,26 there were also a few cautionary accounts on its harmful effect.27

Malondialdehyde levels show the degree of lipid peroxidation directly and damage cell indirectly.28 The lowest level of MDA was observed in the control group and increased in experimental groups. Kamel Mohamed found that treatment with aloe vera caused an increase in antioxidant activity in diabetic rats.29 It also significantly reduced the lipid peroxidation and MDA production. In some studies beneficial effects of the aloe vera on antioxidant defense has been reported. Use of aloe vera juice enhanced the levels of antioxidant enzymes in mouse.30 Anilakumar et al. showed that some constituents of aloe vera gel extract such as Barbalvyyn, glucomannan, asmanan, minerals, flavonoids and tannic acid may be responsible for reducing oxidative stress and induced toxicity.12 Farahi et al. found that phenolic compounds (flavonoids, proanthocyanidin) have strong antioxidant activity for the removal of free radicals and oxidative reactions are completed.18 The FRAP shows extracts reducing power and its ability to reduce Fe3+ to Fe2+. It had been reported that reducing power of aloe vera like other medicinal plants is related to phenolic constituents.11 Our findings suggested that in O. mykiss, phenolic constituents of aloe vera did not enhance antioxidant activity, even reduced it. Decrease in FRAP may be caused by inhibition of activity of superoxide dismutase, catalase and glutathione peroxidase in O. mykiss following dietary administration of aloe vera.31

Our results showed that dietary administration of aloe vera in O. mykiss t did not have positive effect on growth performance but also adversely affected lipid peroxidation that resulted to increase in MDA.


    1. Lawless J, Allan J. Aloe vera-natural wonder cure. London, UK: Harper Collins Publishers 2000, 192.
    2. Bruneton J. Pharmacognosy, phytochemistry, medicinal plants. Paris, France: Lavoisier 1995, 1136.
    3. Mesbah M, Alishahi M, Saberi Afshar F, et al. Effect of aloe vera extract on the wound healing process in common carp (Cyprinus carpio). In proceedings: The 1st International congress on aquatic animal health management and diseases. Tehran, Iran 2009; 230.
    4. Alishahi M, Ranjbar M, Ghorbanpour M, et al. Effects of dietary aloe vera on specific and nonspecific immunity of common carp (Cyprinus carpio). J Vet Res 2010; 3: 85-91.
    5. Heidarieh M, Mirvaghefi AR, Sepahi A, et al. Effects of dietary aloe vera on growth performance, skin and gastro-intestine morphology in rainbow trout (Oncorhynchus mykiss). Turkish J Fish Aquat Sci 2013; 13: 367-373.
    6. Livingstone DR. Contaminant-stimulated reactive oxygen species production and oxidative damage in aquatic organisms. Mar Pollut Bull 2001; 42: 656-666.
    7. Halliwell B, Gutteridge JMC. Lipid peroxidation: A radical chain reaction. In: Halliwell B, Gutteridge JMC. (Eds.). Free radicals in biology and medicine. Oxford, UK: Clarendon Press 1996; 188-266.
    8. Trenzado C, Hidalgo MC, García-Gallego M, et al. Anti-oxidant enzymes and lipid peroxidation in sturgeon Acipenser naccarii and trout Oncorhynchus mykiss: A comparative study. Aquaculture 2006; 254:758-767.
    9. Winston GW, Di Giulio RT. Pro-oxidant and antioxidant mechanism in aquatic organisms. Aquatic Toxicol 1991; 19:137-161.
    10. Huang J, Tian L, Wu X, et al. Effects of dietary riboflavin levels on antioxidant defense of the juvenile grouper Epinephelus coioides. Fish Physiol Biochem 2010; 36(1):55-62.
    11. Chen YJ, Liu YJ, Tian LX, et al. Effect of dietary vitamin E and selenium supplementation on growth, body composition, and antioxidant defense mechanism in juvenile largemouth bass (Micropterus salmoide) fed oxidized fish oil. Fish Physiol Biochem 2013; 39: 593-604.
    12. Anilakumar KR, Sudarshanakrishna KR, Chandra-mohan G, et al. Effect of aloeveragel extract on anti-oxidant enzymes and azoxymethane-induced oxidative stress in rats. Ind J Exp Biol 2010; 48: 837-842.
    13. Sethi J, Gupta A, Sood S, et al. Antioxidant effects of aloe vera in experimentally induced diabetes mellitus. Int J Pharm Sci Res 2012; 3(8): 2522-2526.
    14. Misra CK, Kumar DB, Mukherjee SC, et al. Effect of long term administration of dietary β-glucan on immunity, growth and survival of Labeo rohita fingerlings. Aquaculture 2006; 255: 82-94.
    15. Buege JA, Aust SD. Microsomal lipid peroxidation. Meth Enzymol 1978; 52: 302-310.
    16. Koracevic D, Koracevic G, Djordjevic V, et al. Method for the measurement of antioxidant activity in human fluids. J Cli Pathol 2001; 54:356-361.
    17. Alishahi M. Effect of different levels of crude extract of aloe vera on growth indices and resistance to Aeromonas hydrophila infection in Amphilophus labiatus. Maine Biology 2010; 2: 41-46.
    18. Farahi A, Kasiri M, Sudagar M, et al. Effect of dietary supplementation of Melissa officinalis and aloe vera on hematological traits, lipid oxidation of carcass and performance in rainbow trout (Oncorhynchus mykiss). Online J Anim Feed Res 2012; 2(1): 01-05.
    19. Ahilan B, Nithiyapriyatharshini A, Ravaneshwaran K. Influence of certain herbal additives on the growth, survival and disease resistance of goldfish, Carassius auratus (Linnaeus). Tamil Nadu J Vet Anim Sci 2010; 6(1): 5-11.
    20. Barreto MSR, Menten JFM, Racanicci AMC, et al. Plant extracts used as growth promoters in broilers. Braz J Poult Sci 2008; 10:109-115.
    21. Nasir Z, Grashorn MA. Effect of Echinacea purpurea and Nigella sativa supplementation on broiler performance, carcass and meat quality. J Anim Feed Sci 2010;19:94-104.
    22. Andallu B, Varadacharyulu NC. Antioxidant role of mulberry (Morus indica L. cv. Anantha) leaves in streptozotocin-diabetic rats. Clinica Chimica Acta 2003; 338:3-10.
    23. Wu JH, Xu C, Shan CY, et al. Antioxidant properties and PC12 cell protective effects of APS-1, a polysaccharide from aloe vera var. chinensis. Life Sci 2006; 78:622-630.
    24. Sabeh F, Wright T, Norton SJ. Isozymes of superoxide dismutase from aloe vera. Enzymes Protein 1996; 49: 212-221.
    25. Lee KY, Weintraub ST, Yu BP. Isolation and identification of a phenolic antioxidant from aloe barbadensis. Free Radical Biol Med 2000; 28: 261-265.
    26. Chitra P, Sajithlal GB, Chandrakasan G. Influence of aloe vera on the healing of dermal wounds in diabetic rats. J Ethnopharmacol 1998; 59: 195-201.
    27. Reynolds T, Dweck AC. Aloe vera leaf gel: A review update. J Ethnopharmacol 1999; 68: 3-37.
    28. Peng S, Chen L, Qin JG, et al. Effect of dietary vitamin E supplementation on growth performance, lipid peroxidation and tissue fatty acid composition of black sea bream (Acanthopagrus schlegeli) fed oxidized fish oil. Aquacult Nutr 2009; 15:329-337.
    29. Kamel Mohamed EA. Antidiabetic, anti-hyper-cholestermic and antioxidative effects of aloe vera gel. Aust J Basic Appl Sci 2011; 5(11): 1321-1327.
    30. Rajasekaran S, Sivagnanam K, Subramanian S. Anti-oxidant effect of aloe vera gel extract in streptozotocin-induced diabetes in rats. Pharmacol Rep 2005; 57:90-96.
    31. Golestan G,Salati A P, Keyvanshokoh S,et al. Effect of dietary aloe vera on serum antioxidant enzymes in rainbow trout fingerlings. In proceedings: The 5th international congress of biochemistry and molecular biology. Yazd, Iran 2013; 776-778.