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The Effects of Marigold As Natural Carotenoids on Scale Chromatophores’ Variations in Blue Gourami Under Different Stocking Densities

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The Effects of Marigold As Natural Carotenoids on Scale Chromatophores’ Variations in Blue Gourami Under Different Stocking Densities Journal of Survey in Fisheries Sciences 5(2) 29-36 2019 The effects of Marigold as natural carotenoids on scale chromatophores’ variations in blue gourami under different stocking densities Jorjani M.1*; Sharifroohani M.2; Mirhashemi Rostami A.1; Enayat Gholampoor T.1; Mirzaei M.R.3; Tan Shau Hwai A.4 Received: May 2018 Accepted: October 2018 Abstract Skin coloration is important in ornamental fish. Fish coloration is due to the presence of chromatophores, which contain pigments and are usually located in dermis. In this study, the effects Marigold as natural carotenoids was investigated on fish scale chromatophores’ variations under different stocking densities. For this, diet containing 2.5% Marigold along with a control diet were fed to the fish held at two stocking densities of 20 and 30 fish (0.6 and 0.9 fish/Liter). After 70 d, changes in chromatophores were monitored in fish scales upper lateral line. The fish initial weight was 0. 80±0.02 g. Each treatment had three replications. According to the results, four different chromatophores, including Punctate, Punctate-stellate, Stellate, Stellate-reticulate were observed in the fish at the higher density. The results suggest that increase in stocking density alters chromatophores type and results in hypermelanosis that affects body surface and neural system; thus chromatophores indicate stress contamination. Keywords: Blue gourami, Marigold, Chromatophores, Density, Skin color Downloaded from sifisheriessciences.com at 14:31 +0330 on Thursday September 23rd 2021 [ DOI: 10.18331/SFS2019.5.2.4 ] 1- Inland Waters Aquatic Stocks Research Center, Gorgan 2- Agricultural Research Education & Extension Organization, Tehran, Iran 3- Offshore Fisheries Research Center, Chabahar, Iran 4- School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia *Corresponding author’s Email: [email protected] 30 Jorjani et al., The effects of Marigold as natural carotenoids on scale chromatophores’ … Introduction additives, use of plant pigments has Skin coloration is important in been studied extensively for example ornamental fish like blue gourami. red cabbage (Asadi and Allaf Color is an important factor Noveirian, 2015), carrot and beetroot determining ornamental fish price in (Adhami et al., 2016). Marigold world market. Color of the naturally- might be important in fish colored fish often fades under chromatophores increase and intensive rearing conditions. consequently color change because it Ornamental fish producers are is cheap, easily available, natural always seeking methods for skin and rich in pigments. coloration increase. Also, they are Blue gourami (Trichogaster looking for natural pigments to trichopterus) is a species found in replace synthetic pigments, because ponds, lakes, rice farms, channels the synthetic pigments are expensive and rivers in South-East Asia (Ramamoorthy et al., 2010). Fish (Rainboth, 1996). Degani et al. (1992) coloration is due to the presence of stated that this species can be a chromatophores, which contain candidate for aquaculture, because it pigments and are usually located in is consumed in some countries such dermis. Chromatophores also present as Thailand. Thus, change in in epidermis, peritoneum, eyes and coloration can play an important role other organs (Sattari, 2002). in marketability of this species. Chromatophores are divided into five Aquaculture has been developing groups: Punctate, Punctate-stellate, as a global industry; it includes Stellate, Stellate-reticulate and production of different types of Reticulate (Muralidharan and Pillai, marine and ornamental fish, and 2012). mollusks (Meyers, 1994). To meet There are four main groups of increasing demands for freshwater pigments responsible for tissue and fish, fish producers should keep the skin coloration in animals and plants fish under maximum allowable namely melanin, purine, pyridium density to produce high quantity of and carotenoid. Carotenoids are the fish (Olivier and Kaiser, 1997). main pigment in fish. Carotenoids Optimum stocking density in belong to a family with more than aquaculture is an important factor in 600 fat-soluble natural pigments. determination of production costs Downloaded from sifisheriessciences.com at 14:31 +0330 on Thursday September 23rd 2021 [ DOI: 10.18331/SFS2019.5.2.4 ] Fish and other animals are not able and investment (Metusalach et al., to synthesize carotenoids, thus they 1999). In addition to production are depended on dietary source. cost, stocking density affects fish After dietary intake, carotenoids can be survival, growth, welfare and transformed to other compounds. Due nutrition (Braun et al., 2010). Over- to some adverse effects of dietary crowding may result in oxidative Journal of Survey in Fisheries Sciences 5(2) 2019 31 stress, and consequently vitamin and Diets mineral depletion; these compounds To prepare the diets, a commercial have important roles in immune feed, specific for ornamental fish system, thus fish go weak and (0.5 mm in diameter; Biomar, susceptible to diseases (Braun et al., France), was weighed and then 2010). Van der Salm et al. (2004) mixed with 2.5% Marigold. Desired reported that stocking density has an volume of water was added to the important role in skin coloration of mixture to form dough (Asadi and several fish species. In the present Allaf Noveirian, 2015). The dough study, the effects of Marigold was transformed to sticks using a dietary supplementation was meat grinder (1 mm die). The sticks investigated on chromatophores type were dried overnight, because and number in blue gourami. carotenoids are susceptible to high temperature (Niazmand, 2015). The Materials and methods control die was prepared in similar Fish and rearing conditions way, but without Marigold Blue gourami larvae were progenies supplementation. The diets were kept of broodstocks propagated in a local in refrigerator until use. At each meal, ornamental fish propagation farm required amounts of the diets were (Shahriyari farm, Golestan, Iran). weighed and offered to Larvae were transferred to laboratory corresponding aquaria. Wastes were (Inland Water Aquatic Stocks siphoned daily and 30-50% new Research Center, Gorgan, Iran) and water was added to each aquarium. were kept in holding aquaria to The diets proximate composition reach 0.80 ± 0.02 g in weight. Then was determined according to AOAC the fish were stocked in 12 aquaria (1995). Crude protein, lipid and ash (60×30×30 cm; 35 L water) at the were measured using Kjeldahl, densities of 20 and 30 fish per Soxhlet, calorimeter bomb and oven. aquarium (0.6 and 0.9 fish/Lit ). The Proximate compositions are presented fish were fed either control, or in Table 1. Total carotenoid was control diet supplemented with either determined using Torrissen and 2.5% Marigold for ten weeks. Each Naevdal (1984). treatment consisted of three aquaria. Feeding rate was 2.5-3.5% of Water physic-chemical parameters Downloaded from sifisheriessciences.com at 14:31 +0330 on Thursday September 23rd 2021 [ DOI: 10.18331/SFS2019.5.2.4 ] biomass divided into two meals at during the experiment morning and evening (Degani et al., The aquaria were filled with tape water 1990). of city Gorgan. Water was aerated (24 h) for dechlorination.An air stone connected to a central air pump was placed in each aquarium. 32 Jorjani et al., The effects of Marigold as natural carotenoids on scale chromatophores’ … Table 1: Proximate analysis of blue gourami diet containing 2.5% Marigold. Ingredients Crude Fat Ash Energy Crude Total carotenoid protein (%) (%) (%) (Cal/g) Fiber (%) (mg/kg) Control 41.43 8.63 11.35 4598.6 2.09 20 Marigold-diet 40.62 8.32 11.39 4501.76 2.69 40.47 Water temperature was fixed using a decreased at 42% and 40%, heater (100 W) in each aquarium. respectively. No significant difference Average water temperature, dissolved (p>0.05) in the contents of punctate- oxygen and pH were 26.50±0.02, stellate has been found between M0.6 7.15±0.02 and 8.35±0.02, respectively. compared to CG0.6 (Table 2). However, results indicated that To determine change in punctate-stellate at M0.9 increased at chromatophores of blue gourami at 89% compared to CG0.9. No significant different stocking densities differences (p>0.05) in the contents of To determine alteration in stellate have been found between M0.6 chromatophores’ count, 18 scales compared to CG0.6 (Table 2). were sampled from each treatment. However, results indicated that stellate The samples were taken from upper at M0.9 increased 4 times compared to lateral line and placed in separate CG0.9. Comparative analysis for pockets. To count chromatophores, stellate-reticulate also showed same the scales were placed into water to trend. Significant difference (p<0.05) in remove fatty materials easily. The the contents of stellate-reticulate has scales were then dried and been found between M0.6 compared to monitored under light microscopy CG0.6 (Table 2). Results indicated that connected to an LCD. stellate-reticulate at M0.9 significantly increased compared to CG0.9. Stellate- Statistical analysis reticulate amounts revealed increasing Variances equality was checked by trend in M0.6 and M0.9 in comparison Levene’s test. Data were analyzed with their controls. M0.6 and M0.9 using Independent T-test. Significance enhanced 3 and 20 times compared to was determined at confidence limit of CG0.6 and CG0.9, respectively (Table 95%. Data are presented as 2). mean±SEM. Software packages In the scale chromatophores SPSS20 and Excel were used for analysis, four out of five Downloaded from sifisheriessciences.com at 14:31 +0330 on Thursday September 23rd 2021 [ DOI: 10.18331/SFS2019.5.2.4 ] analysis. chromatophores comprising Punctate, Punctate-stellate, Stellate and Stellate- Results and discussion reticulate chromatophores were Results showed that amount of punctate observed in blue gourami fish as shown significantly decreased at M0.6 and in Fig. 1. M0.9 in comparison with CG0.6 and CG0.9 (p<0.05). Punctate amount Journal of Survey in Fisheries Sciences 5(2) 2019 33 Table 2: The number of chromatophores of blue gourami fed with 2.5% Marigold powder at different stocking densities.
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