RESEARCH ARTICLE

Tank colours do not change the effects of extreme temperatures on the productive parameters, but skeletal deformities of golden trevally

Van Manh Ngo1, Khuong V. Dinh1,2,*https://orcid.org/0000-0003-0766-9148, Bich Lien Chau1, Diep Minh Luc1
Author Information & Copyright
1Cam Ranh Centre for Tropical Marine Research and Aquaculture, Institute of Aquaculture, Nha Trang University, Nha Trang, Vietnam
2Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, Oslo 0371, Norway
*Corresponding author: Khuong V. Dinh, Cam Ranh Centre for Tropical Marine Research and Aquaculture, Institute of Aquaculture, Nha Trang University, Nha Trang, Vietnam, Tel: +84-4794725058, E-mail: van.k.dinh@ibv.uio.no

Copyright © 2023 The Korean Society of Fisheries and Aquatic Science. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Apr 27, 2023; Revised: May 29, 2023; Accepted: May 31, 2023

Published Online: Aug 31, 2023

Abstract

The objective of this study was to evaluate how the tank colours may change the effects of extreme temperature on the survival, growth, and quality of juvenile golden trevally (Gnathanodon speciosus). The experiment was set up with fifteen treatments of five tank colours (blue, red, yellow, grey, and white) and three temperatures (30°C, 32°C, 34°C) with three replications. Fish performance was assessed for four weeks. The results showed that tank colours and elevated temperatures affected the quality of golden trevally juveniles. The survival and growth rate of fish tend to decrease gradually, but the deformation rate of fish tended to increase in the order of tank colours: red, yellow > grey, blue, and white. The growth and survival rate of fish gradually decreased when the rearing temperature increased from 30°C to 34°C and this effect was independent of tank colors. Importantly, the deformation rate increased under elevated temperature, particularly in blue and white tanks with potential long-term effects. It is, therefore, not recommended to use blue and white tanks for rearing the golden trevally juveniles, particularly during extremely high temperatures from heatwave events.

Keywords: Golden trevally; Gnathanodon speciosus; Tank color; Extreme temperature

Introduction

Tropical marine aquaculture farmed fish species are rearing close to their thermal temperature optimum. These species are highly vulnerable to large and abrupt temperature changes (i.e., marine heatwaves [MHWs]) as the temperature increase during a MHW can exceed their upper thermal optimum (Tewksbury et al., 2008). Extreme temperatures from MHWs may result in increased mortality and reduced growth rate of tropical farmed fish (Le et al., 2020, 2021). In tropical countries, aquaculture plays an important role in coastal communities (Basset et al., 2013). For example, finfish aquaculture production in Southeast Asian countries provides more than 20% of global fish production (FAO, 2022). In the next three decades, up to 40% of aquaculture species, particularly farmed finfish may not be suitable for aquaculture in tropical regions (Oyinlola et al., 2020). This may threaten the income and food security of coastal communities.

There has been an increasingly awareness of how the color of aquaculture systems (e.g., tank colour) may affect feeding, growth, thereby size disparity and cannibalism and improve hatchery production efficiency and profitability (McLean, 2021). Light intensity in the rearing systems may be affected by the colour. For example, colour may affect visibility of fish larvae and juveniles to prey items (Dehmelt et al., 2021; Ma et al., 2015). Tank colours have been known to affect key behaviours e.g., feeding (Bera et al., 2019; El-Sayed & El-Ghobashy, 2011; Wang et al., 2016), and phygiological parameters e.g., enzyme activities and digestion (Rungruangsak-Torrissen et al., 2006; Santisathitkul et al., 2020). The effect of tank colour on fish growth is species-specific. Milkfish larvae (Chanos chanos) showed the best performance in yellow tanks (Bera et al., 2019), whereas black or dark red is the suitable tank colour for the larvae of white bass (Morone chrysops), striped bass (Morone saxatilis) (Denson & Smith, 1996) and Golden pompano (Trachinotus ovatus) (Ma et al., 2015), pangas catfish (Pangasius pangasius), Eurasian perch (Perca fluviatilis, L.) (Tamazouzt et al., 2000). Contrarily, larvae of Asian catfish magur (Clarius magur) prefer white tanks (Ferosekhan et al., 2020) and tambaqui (Colossoma macropomum) larvae prefer light green tanks (Pedreira & Sipaúba-Tavares, 2001). Finally, the survival and growth performance, key parameters of fish production may be affected by tank colours (Bera et al., 2019; Ferosekhan et al., 2020).

The golden trevally (Gnathanodon speciosus) is a commercially valuable species in Vietnam. They distribute widely in the tropical and subtropical waters in Indo-Pacific and Atlantic Oceans. The golden trevally is a new farmed fish in Vietnam. Artificial seed production of this species is successful in captivity in the hatcheries. This species growth fast and has a high market value. To the best of our knowledge, no reports on the impact of tank colours combined with elevated temperature on golden trevally are available. This is a highly relevant topic given the increasing frequency, intensity and severity of extreme temperatures from MHW events in the last decade with huge socioeconomic impacts (Smith et al., 2021). Therefore, the objective of this study was to evaluate the effect of tank color on the quality of golden trevally juveniles such as growth, survival rate, salinity shock and deformation rate reared at elevated temperatures.

Materials and Methods

Ethical statement

Based on the National Regulations for the Use of Animals in Research in Vietnam, golden trevally (G. speciosus) is not listed in two groups IB (endangered and critically endangered species) and IIB (threatened and rare species) (Decree32/, 2006/ND-CP, 2006). Therefore, this study does not require a permit or ethical approval. However, the authors have implemented their best practice of using animals in research.

Experimental fish and treatments

The experiments were conducted at the Cam Ranh Centre for Tropical Marine Research and Aquaculture, Institute of Aquaculture, Nha Trang University using round fiberglass reinforced plastic (FRP) tanks (diameter, 0.7 m; height, 0.8 m; water capacity, 0.1 m3) with conical bottom (manufactured by Institute for Ship Research and Development, Nha Trang University). The inner surface of the tanks was painted with Composite Epoxy paint from Chokwan Vina Company Ltd. based on JOTUN RAL standard colour chart (red code: RAL 3000-flame red; blue code: RAL 5012-ligh blue; yellow code: RAL 1003-signal yellow; grey code: RAL 7040-window grey; white code: RAL 1003-signal white (http://sonjotun.vn/bang-mau-ral-voi-2013-mau-son-co-ban/250/1298.html). Clean filtered seawater treated with 20 ppm chlorine was filled into the rearing tanks 12 h before stocking the juvenile. Dissolved oxygen (5–6 mg/L) was maintained by a single air stone placed at the bottom of each tank. The salinity (30 PSU) and pH (7.89–8.05) were maintained during the experimental period. Triplicate sets of golden trevally juveniles were reared in white, blue, grey, yellow and red tanks combined with three temperatures (30°C, 32°C, and 34°C) for 4 weeks. The total experimental units were 45 tanks. The temperature was controlled by heaters (HZ-Q5, 500W, Ou Gecali, Shanghai, China). Continuous illumination of 1,200–1,600 lux (24/0 h light/darkness) was applied (Alejos & Serrano, 2018; Mapunda et al. 2021) using natural light during the day and neon light bulbs at night. Nine thousand golden trevally juveniles with an average initial weight of 0.12 ± 0.04 g and initial length of 17.24 ± 1.65 mm were procured from a local farm. After two days of acclimation, the fish were randomly distributed into 45 FRP tanks (200 individuals per tank). During the acclimation and throughout a 30-day experimental period, the fish were fed to satiation twice daily at around 8:00 and 17:00 with a commercial diet (Inve NRD G8-12, Inve, Wachirabarami, Thailand), containing 55% protein, 10% fat and 8% moisture. Uneaten feed and feces were siphoned daily before morning feed.

Juvenile performance

We determined the growth parameters of G. speciosus juveniles including the increase in body weight (BW, g), total length (TL, cm), the specific growth rate (SGR) in length and weight.

Weight gain (BW) = Final BW (g) Initial BW (g) .
SGR for BW = ( [ ln BW 2 ln BW 1 ] × Days of experiment 1 ) × 100.
TL gain = Final TL (cm) Initial TL (cm) .
SGR for TL = ( [ ln TL 2 ln TL 1 ] × Days of experiment 1 ) × 100.
Feed conversion ratio (FCR) = (kg Diet consumed in dry mass) × ( kg Final wet biomass kg Initial wet biomass + kg Wet biomass dead fish ) 1 .
Finally, Survival  ( % ) = 100 × Final fish number / Initial fish number .
Salinity shock

After the experimental period, 10 juveniles from each tank were randomly collected and shocked at three different salinities (0, 5 or 10 ppt) at the temperature of 30°C as osmotic stress only. The survival rate was observed and calculated after 5, 10 or 15 minutes.

Skeletal deformities

To determine the skeletal deformities, we stained the fish bone at the termination of the feeding experiment following protocols detailed by Darias et al. (2010). Fish samples were first fixed in a formalin solution until staining skeletons. Before staining, fish juveniles were transferred to distilled. Subsequently, fish were stained with alcian blue water for 24 h. We used 100% ethanol and 1%KOH solution to neutralize the residual acid in the larvae tissues, then rehydrated fish by submerging them in ethanol solutions (95%, 70%, 40%, 15%) for 15 min each. Subsequently, we used 3% H2O2 and 1%KOH solutions to remove black pigmentations in fish samples and then stained them with Alizarin red solution for 20 h. G. speciosus juveniles were washed with distilled water and subsequently with 1%KOH solution to eliminate the staining background before incubating in 40% glycerol + 60% of 1%KOH in 2 h and 70% glycerol + 30% of 1%KOH in 6 h. The stained juveniles were preserved in 100% glycerol. The morphology and abnormalities of juvenile skeletons were observed, identified and imaged using a stereomicroscope (Amscope SM-2T-EB, AmScope, Irvine, CA, USA) with a camera (a resolution of 10 MP).

Statistical analysis

All data were visualized as mean ± SD. Statistical procedures were performed using SPSS software (SPSS 22.0, Armonk, NY, USA). Assumptions for two-way analysis of variances were checked with the Kolmogorov-Smirnov and Levene’s tests, respectively. Duncan post hoc tests (p < 0.05), were used to determine significant differences between the experimental groups.

Results

Survival rate

In all colours, survival was generally decreased following the increase of temperature from 30°C to 34°C (main effect of temperature, p < 0.05; Table 1 and Fig. 1). The effects of tank colours on survival following the order: survival in yellow = red > white = grey = blue colour of tank (main effect of tank colour, p < 0.05; Table 1 and Fig. 1), but this color effect was independent on temperatures (tank colour × temperature, p > 0.05).

Table 1. Statistical results of the effects of elevated temperature and tank color on survival rate of the golden trevally juveniles (Gnathanodon speciosus)
Effect df1, df2 F-value p-value
Tank color 4, 30 5.95 0.002
Temperature 2, 30 6.857 0.004
Tank color × temperature 8, 30 0.705 0.685
Download Excel Table
fas-26-8-461-g1
Fig. 1. Survival rate of the golden trevally juveniles (Gnathanodon speciosus) reared in five different tank colours and three temperatures.
Download Original Figure
Growth performance

All growth parameters including final length and weight, increased length and weight, SGRs, and FCR of the golden trevally juveniles were significantly decreased by increasing temperatures from 30°C to 34°C (main effect of temperature, p < 0.05; Table 2). Temperature effects on the growth performance of the golden trevally juveniles were similar in five tank colours (Table 2). These parameters were not significantly different by five tank colors (p > 0.05; Table 2).

Table 2. BW and TL, SGR, FCR of the golden trevally juvenile with various TC at three Ts
Treatments Initial TL (mm) Initial BW (g) Final TL (mm) Final BW (g) Gain TL (mm) Gain BW (g) SGRTL (%/day) SGRBW (%/day) FCR
T (°C) TC
30 Blue 17.24 ± 1.65 0.12 ± 0.04 56.78 ± 2.41 53.56 ± 2.75 51.33 ± 2.80 2.76 ± 0.36 2.27 ± 0.26 2.17 ± 0.30 1.19 ± 0.17
Red 17.24 ± 1.65 0.12 ± 0.04 58.11 ± 2.24 54.89 ± 2.39 52.22 ± 3.46 2.90 ± 0.34 2.45 ± 0.18 2.16 ± 0.33 1.08 ± 0.13
Grey 17.24 ± 1.65 0.12 ± 0.04 56.44 ± 2.57 52.67 ± 3.23 50.67 ± 2.86 2.71 ± 0.34 2.23 ± 0.24 1.93 ± 0.20 1.14 ± 0.12
Yellow 17.24 ± 1.65 0.12 ± 0.04 57.67 ± 2.35 54.22 ± 1.71 51.22 ± 2.08 2.80 ± 0.33 2.37 ± 0.35 2.17 ± 0.17 1.11 ± 0.13
White 17.24 ± 1.65 0.12 ± 0.04 55.44 ± 1.33 52.33 ± 1.55 48.67 ± 1.89 2.51 ± 0.22 2.20 ± 0.34 1.93 ± 0.28 1.21 ± 0.12
32 Blue 17.24 ± 1.65 0.12 ± 0.04 56.78 ± 2.41 53.56 ± 2.75 51.33 ± 2.80 2.76 ± 0.36 2.27 ± 0.26 2.17 ± 0.30 1.19 ± 0.17
Red 17.24 ± 1.65 0.12 ± 0.04 58.11 ± 2.24 54.89 ± 2.39 52.22 ± 3.46 2.90 ± 0.34 2.45 ± 0.18 2.16 ± 0.33 1.08 ± 0.13
Grey 17.24 ± 1.65 0.12 ± 0.04 56.44 ± 2.57 52.67 ± 3.23 50.67 ± 2.86 2.71 ± 0.34 2.23 ± 0.24 1.93 ± 0.20 1.14 ± 0.12
Yellow 17.24 ± 1.65 0.12 ± 0.04 57.67 ± 2.35 54.22 ± 1.71 51.22 ± 2.08 2.80 ± 0.33 2.37 ± 0.35 2.17 ± 0.17 1.11 ± 0.13
White 17.24 ± 1.65 0.12 ± 0.04 55.44 ± 1.33 52.33 ± 1.55 48.67 ± 1.89 2.51 ± 0.22 2.20 ± 0.34 1.93 ± 0.28 1.21 ± 0.12
34 Blue 17.24 ± 1.65 0.12 ± 0.04 56.78 ± 2.41 53.56 ± 2.75 51.33 ± 2.80 2.76 ± 0.36 2.27 ± 0.26 2.17 ± 0.30 1.19 ± 0.17
Red 17.24 ± 1.65 0.12 ± 0.04 58.11 ± 2.24 54.89 ± 2.39 52.22 ± 3.46 2.90 ± 0.34 2.45 ± 0.18 2.16 ± 0.33 1.08 ± 0.13
Grey 17.24 ± 1.65 0.12 ± 0.04 56.44 ± 2.57 52.67 ± 3.23 50.67 ± 2.86 2.71 ± 0.34 2.23 ± 0.24 1.93 ± 0.20 1.14 ± 0.12
Yellow 17.24 ± 1.65 0.12 ± 0.04 57.67 ± 2.35 54.22 ± 1.71 51.22 ± 2.08 2.80 ± 0.33 2.37 ± 0.35 2.17 ± 0.17 1.11 ± 0.13
White 17.24 ± 1.65 0.12 ± 0.04 55.44 ± 1.33 52.33 ± 1.55 48.67 ± 1.89 2.51 ± 0.22 2.20 ± 0.34 1.93 ± 0.28 1.21 ± 0.12
Means of main effect
T (°C) 30 17.24 0.12 56.89B 2.74B 39.65B 2.61B 3.96B 10.17B 1.15A
32 17.24 0.12 53.53A 2.30A 36.29A 2.18A 3.75A 9.54A 1.45B
34 17.24 0.12 50.82A 2.07A 33.58A 1.95A 3.56A 9.19A 1.62B
TC Blue 17.24 0.12 53.89 2.40 36.65 2.28 3.76 9.64 1.41
Red 17.24 0.12 55.07 2.50 37.83 2.38 3.83 9.84 1.30
Grey 17.24 0.12 53.26 2.29 36.02 2.17 3.71 9.55 1.42
Yellow 17.24 0.12 54.37 2.45 37.13 2.33 3.80 9.76 1.33
White 17.24 0.12 52.15 2.21 34.91 2.09 3.67 9.37 1.57
ANOVA (p-values)
 T NS NS 0.001 0.002 0.001 0.002 0.001 0.002 0.003
 TC NS NS 0.647 0.743 0.647 0.740 0.718 0.685 0.594
 T × TC NS NS 0.99 0.99 0.99 0.99 0.99 0.99 0.982

Value is presented as tank mean ± SEM (n = 3). Results were based on two-way ANOVA. Superscripts after each value on the same row indicate results of pairwise comparisons. Only interactions are indicated when present.

A,B Different upper case letters indicate significant differences (p < 0.05) between temperatures.

T, temperature; TC, tank colour; TL, total length; BW, body weight; SGR, specific growth rate; FCR, feed conversion ratio; NS, not significant; ANOVA, analysis of variance.

Download Excel Table
Salinity shock

At a salinity of 10 ppt, the survival rate of the golden trevally juvenile was 100% in all treatments (p > 0.05; Table 3). However, the significant differences between treatments were retained at the 5 ppt and 0 ppt of salinity shock (p < 0.05; Table 3). In both salinities of 0 and 5 ppt, survival was reduced in juveniles reared under elevated temperatures (p < 0.05; Table 3). The colour tank strongly affected the survival of the golden trevally juveniles in salinity shock at 0 ppt or 5 ppt (p < 0.05; Table 3). At a salinity of 0 ppt, the survival rate of the golden trevally juveniles was the highest in red tanks and seemed to be lowest in blue tanks. However, the combined effect of tank colours and elevated temperatures was not significantly affected the survival rate of fish juveniles for salinity shock at 0 ppt or 5 ppt (p > 0.05; Table 3).

Table 3. The survival rate (%) of the golden trevally after 15 minutes for salinity shock with various TC at three Ts
Treatments Salinity 0 ppt (%) Salinity 5 ppt (%) Salinity 10 ppt (%)
T (°C) TC
30 Blue 13.33 ± 13.33 93.33 ± 3.33 100
Red 90.00 ± 10.00 96.67 ± 3.33 100
Grey 70.00 ± 5.77 93.33 ± 3.33 100
Yellow 86.67 ± 3.33 96.67 ± 3.33 100
White 50.00 ± 20.00 63.33 ± 16.67 100
32 Blue 6.67 ± 6.67 83.33 ± 3.33 100
Red 80.00 ± 10.00 80.00 ± 5.77 100
Grey 63.33 ± 8.82 83.33 ± 6.67 100
Yellow 73.33 ± 6.67 83.33 ± 6.67 100
White 36.67 ± 13.33 46.67 ± 13.33 100
34 Blue 13.33 ± 13.33 56.67 ± 12.02 100
Red 70.00 ± 10.00 83.33 ± 3.33 100
Grey 53.33 ± 3.33 76.67 ± 3.33 100
Yellow 76.67 ± 3.33 86.67 ± 3.33 100
White 13.33 ± 3.33 26.67 ± 3.33 100
Means of main effect
T (°C) 30 62.00B 88.67B 100
32 52.00B 75.33B 100
34 45.33A 66.00A 100
TC Blue 11.11a 77.78b 100
Red 80.00d 86.67b 100
Grey 62.22c 84.44b 100
Yellow 78.89d 88.89b 100
White 33.33b 45.56a 100
ANOVA (p-values)
 T 0.041 < 0.0001 NS
 TC < 0.0001 < 0.0001 NS
 T × TC 0.79 0.38 NS

Value is presented as tank mean ± SEM (n = 3). Results were based on two-way ANOVA. Superscripts after each value on the same row indicate results of pairwise comparisons. Only interactions are indicated when present.

A,B Different upper case letters indicate significant differences (p < 0.05) between temperatures.

a–d Different lower case letters indicate significant differences between tank colours.

T, temperature; TC, tank colour; NS, not significant; ANOVA, analysis of variance.

Download Excel Table
Skeletal deformations

The deformation rate increased significantly by increasing temperature from 30°C to 34°C (main effect of elevated temperature, p < 0.05; Table 4 and Fig. 2). The deformation also increased was highest in white, followed by grey, blue, yellow, and lowest in red tanks (main effect of tank color, p < 0.05; Table 4 and Fig. 2), particularly under higher temperatures (interaction of temperature and colours, p < 0.05; Table 4 and Fig. 2).

Table 4. Statistical results of the effects of elevated temperature and tank color on deformation rate of the golden trevally juvenile
Effect df1, df2 F-value p-value
Tank color 4, 30 229.25 < 0.001
Temperature 2, 30 68.375 < 0.001
Tank color × temperature 8, 30 3.681 0.004
Download Excel Table
fas-26-8-461-g2
Fig. 2. Deformation rate of the golden trevally with various tank color at three temperatures.
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The skeletal staining showed that the golden trevally juveniles reared at the white color tank and grey color tank to receive the deformity at the vertebrate (Fig. 3). However, the golden trevally juveniles reared at the blue, yellow or red color tank were not seen any deformity at the vertebrate (Fig. 3).

fas-26-8-461-g3
Fig. 3. Skeletal deformity of the golden trevally with various tank colour at three temperatures.
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Discussion

This is the first study investigating how the colour of rearing systems may alleviate the heat stress on the golden trevally, a new aquaculture fish species in Vietnam. In general, elevated temperatures resulted in lower survival, reduced growth rate and fish health as indicated by the capacity to survive in a salinity shock, with applications in larvae and juvenile rearing of this species, and tropical finfish species in general.

Effects of elevated temperatures

There has been increasing concern about the thermal tolerance of aquaculture fish species to heat stress with increasing frequency and severity of MHWs under ongoing climate change. For example, 8 of the 10 most severe recorded events have taken place in the past decade (Smith et al., 2021). Extreme temperatures can cause several physiological impairments or dysfunctions such as mitochondrial dysfunction, muscular and heart failures (Ern et al., 2023), a reduced efficiency of oxygen uptake and delivery could also contribute to fish mortality (Pörtner & Farrell, 2008; Pörtner et al., 2017). In tropical aquaculture fish such as cobia showed increased mortality at 32°C (Le et al., 2020; Nguyen et al., 2019). In agreement, the survival of the golden trevally juveniles was also reduced, particularly at 34°C, which may be explained by similar physiological dysfunctions as above.

Similar to the survival, all growth parameters of the golden trevally juveniles were reduced under elevated temperatures, particularly at 34°C which was similar to the temperature effects on other tropical fish species such as cobia Rachycentron canadum (Le et al., 2020; Nguyen et al., 2019; Sun & Chen, 2014; Sun et al., 2006), or spinefoot rabbitfish Siganus rivulatus (Saoud et al., 2008). The reduced growth rate may be a result of lower food conversion efficiency coupled with a higher energy expenditure on basal maintenance (Killen et al., 2016). Indeed, we found a higher FCR at 32°C and 34°C. Rapid upregulation of energetically costly heat shock proteins was observed in tropical fish species e.g., in barramundi following exposure to heat stress (Newton et al., 2012) as a key physiological mechanism to deal with heat stress.

Effects of tank colours

There were some small differences in the survival of the golden trevally juveniles reared at different tank colours; lowest in white tanks and highest yellow and red tanks. Indeed, a previous study has shown that fish reared in red tanks had a lower level of cortisol and higher levels of heat shock protein (HSP) than those in other tanks (Morshedi et al., 2022). HSPs have been well known for their role in coping with general stress in organisms (Morshedi et al., 2022). Interestingly, tank colours could not change the lethal effect of temperatures on the golden trevally juveniles. Several previous studies have found effects of tank colours on the growth rate of marine fish such as milkfish (C. chanos, Bera et al., 2019), barramundi (Lates calcarifer, Morshedi et al., 2022). The yellow color may increase the visibility of milkfish larvae to food items, thereby increasing feeding and growth rate (Bera et al., 2019). The increased growth rate of barramundi reared in red tanks may relate to their feeding behaviours in nature where barramundi prey upon benthic macroinvertebrates and small mid-water pelagic fish (Morshedi et al., 2022). However, we did not find an effect of tank colours on any effect on the growth parameters of the golden trevally juveniles, which may be explained by a similar food conversion efficiency. Indeed, FCRs of the folden trevally juveniles was not affected by rearing tank colours. While we did not assess the feeding rate or feeding behaviours of this species, it was likely that all five tank colours did not create different contrasts between the feed and the background colours.

When challenged to a salinity shock, fish reared in white and blue tanks showed 3–5 times lower survival than those in red and yellow colours. A similar effect of tank colour on the skeletal deformity rate was also observed. Previous studies have suggested that marine fish are more vulnerable to short wavelengths (Villamizar et al., 2011), which may be more in blue, white, or grey tanks than in red and yellow. The low survival of challenged fish in these colours suggests lower fish health, which could be linked to a higher skeletal deformity rate.

Interactive effects of elevated temperatures and tank colours

We found a generally insignificant interaction of heat stress and tank colours on survival, growth rate, and the capacity to tolerate a salinity shock of the golden trevally juveniles, suggesting that tank colours could not mitigate the lethal heat stress from the MHWs. These result suggest that technical adjustments to keep rearing temperature not going beyond the thermal threshold of the the golden trevally juveniles is critically important to reduce the direct heat-induced mortality or growth rate. This is important in the context of increasing frequency and magnitude of MHWs under ongoing climate change (Frölicher et al., 2018). While tank colours could not mitigate visible effects of the heat stress, particularly during a heat wave, temperature-induced increased skeletal deformity rate was much more pronounced in blue tanks and lowest in yellow tanks. However, it would not be possible to detect with the naked eye of live fish juveniles. We would have seriously underestimated the effects of tank colours on the quality of the golden trevally juveniles if we did not assess the skeletal deformities. This is critical as different forms of skeletal deformity may result in long-term effects on survival and growth (Imsland et al., 2006).

Conclusion

In conclusion, elevated temperatures and blue and white rearing tanks resulted in reduced survival, growth and increased mortality of fish challenged with salinity stress, but there were no interactive effects of both factors on these key productive parameters of golden trevally juveniles. However, we found a “hidden interactive effect” of elevated temperature and tank colours on the skeletal deformities, which may affect fish survival and growth during the grow-out period. Blue and white colours are not recommended for rearing golden trevally juveniles, particularly during heat stress such as heatwave periods which are becoming more frequent and severe under ongoing climate change.

Competing interests

No potential conflict of interest relevant to this article was reported.

Funding sources

Not applicable.

Acknowledgements

This research was supported by Vietnam Ministry of Education and Training with the grant B2021-TSN-02 to Manh Van Ngo. We thank Ms. Ngo Thanh Cam and Mr. Nguyen Duc Toan of Institute of Aquaculture – Nha Trang University for helping with juvenile rearing and sampling.

Availability of data and materials

Upon reasonable request, the datasets of this study can be available from the corresponding author.

Ethics approval and consent to participate

This study conformed to the guidance of animal ethical treatment for the care and use of experimental animals.

References

1.

Alejos MS, Serrano AE. Continuous illumination improves growth and survival in the early stage of snubnose pompano Trachinotus blochii. Aquaculture, Aquarium, Conservation & Legislation. 2018; 115:1557-63.

2.

Basset A, Elliott M, West RJ, Wilson JG. Estuarine and lagoon biodiversity and their natural goods and services. Estuar Coast Shelf Sci. 2013; 132:1-4

3.

Bera A, Kailasam M, Mandal B, Sukumaran K, Makesh M, Hussain T, et al. Effect of tank colour on foraging capacity, growth and survival of milkfish (Chanos chanos) larvae. Aquaculture. 2019; 512:734347

4.

Darias MJ, Lan Chow Wing O, Cahu C, Zambonino-Infante JL, Mazurais D. Double staining protocol for developing European sea bass (Dicentrarchus labrax) larvae. J Appl Ichthyol. 2010; 26:280-5

5.

Dehmelt FA, Meier R, Hinz J, Yoshimatsu T, Simacek CA, Huang R, et al. Spherical arena reveals optokinetic response tuning to stimulus location, size, and frequency across entire visual field of larval zebrafish. eLife. 2021; 10e63355

6.

Denson MR, Smith TIJ. Larval rearing and weaning techniques for white bass Morone chrysops. J World Aquac Soc. 1996; 27:194-201

7.

El-Sayed AFM, El-Ghobashy AE. Effects of tank colour and feed colour on growth and feed utilization of thinlip mullet (Liza ramada) larvae. Aquac Res. 2011; 42:1163-9

8.

Ern R, Andreassen AH, Jutfelt F. Physiological mechanisms of acute upper thermal tolerance in fish. Physiology. 2023; 38:141-58

9.

Ferosekhan S, Sahoo SK, Radhakrishnan K, Velmurugan P, Shamna N, Giri SS, et al. Influence of rearing tank colour on Asian catfish, magur (Clarias magur) and pangas (Pangasius pangasius) larval growth and survival. Aquaculture. 2020; 521:735080

10.

Food and Agriculture Organization of the United Nations [FAO]. The state of world fisheries and aquaculture 2022: towards blue transformation. Rome: FAO. 2022.

11.

Frölicher TL, Fischer EM, Gruber N. Marine heatwaves under global warming. Nature. 2018; 560:360-4

12.

Imsland AK, Foss A, Koedijk R, Folkvord A, Stefansson SO, Jonassen TM. Short- and long-term differences in growth, feed conversion efficiency and deformities in juvenile Atlantic cod (Gadus morhua) startfed on rotifers or zooplankton. Aquac Res. 2006; 37:1015-27

13.

Killen SS, Glazier DS, Rezende EL, Clark TD, Atkinson D, Willener AST, et al. Ecological influences and morphological correlates of resting and maximal metabolic rates across teleost fish species. Am Nat. 2016; 187:592-606

14.

Le MH, Dinh KV, Nguyen MV, Rønnestad I. Combined effects of a simulated marine heatwave and an algal toxin on a tropical marine aquaculture fish cobia (Rachycentron canadum). Aquac Res. 2020; 51:2535-44

15.

Le MH, Dinh KV, Pham DH, Phan VU, Tran VH. Extreme temperature differently alters the effects of dietary vitamin C on the growth, immunity and pathogen resistance of Waigieu seaperch, Psammoperca waigiensis. Aquac Res. 2021; 52:5383-96

16.

Ma Z, Guo H, Zhang D, Hu C, Jiang S. Food ingestion, consumption and selectivity of pompano, Trachinotus ovatus (Linnaeus 1758) under different rotifer densities. Aquac Res. 2015; 46:2593-603

17.

Mapunda J, Mtolera MS, Yahya SA, Golan M. Light colour affect the survival rate, growth performance, cortisol level, body composition, and digestive enzymes activities of different Snubnose pompano (Trachinotus blochii (Lacépède, 1801) larval stages. Aquaculture Reports. 2021; 21:100804

18.

McLean E. Fish tank color: an overview. Aquaculture. 2021; 530:735750

19.

Morshedi V, Pradhoshini KP, Tangestani N, Ghasemi A, Sotoudeh E, Gamoori R, et al. Effects of rearing tank colour on growth indices, blood chemistry, digestive enzymes, expression of stress and growth-related genes of Asian sea bass juvenile (Lates calcarifer). Aquac Res. 2022; 53:3780-7

20.

Newton JR, De Santis C, Jerry DR. The gene expression response of the catadromous perciform barramundi Lates calcarifer to an acute heat stress. J Fish Biol. 2012; 81:81-93

21.

Nguyen MV, Espe M, Conceição LEC, Le HM, Yúfera M, Engrola SAD, et al. The role of dietary methionine concentrations on growth, metabolism and N-retention in cobia (Rachycentron canadum) at elevated water temperatures. Aquac Nutr. 2019; 25:495-507

22.

Oyinlola MA, Reygondeau G, Wabnitz CCC, Cheung WWL. Projecting global mariculture diversity under climate change. Glob Change Biol. 2020; 26:2134-48

23.

Pedreira MM, Sipaúba-Tavares LH. Effect of light green and dark brown colored tanks on survival rates and development of tambaqui larvae, Colossoma macropomum (Osteichthyes, Serrasalmidae). Acta Sci. 2001; 23:521-5.

24.

Pörtner HO, Bock C, Mark FC. Oxygen- and capacity-limited thermal tolerance: bridging ecology and physiology. J Exp Biol. 2017; 220:2685-96

25.

Pörtner HO, Farrell AP. Physiology and climate change. Science. 2008; 322:690-2

26.

Rungruangsak-Torrissen K, Moss R, Andresen LH, Berg A, Waagbø R. Different expressions of trypsin and chymotrypsin in relation to growth in Atlantic salmon (Salmo salar L.). Fish Physiol Biochem. 2006; 32:7-23

27.

Santisathitkul N, Thongprajukaew K, Saekhow S, Sandos P, Buntomnimit S, Kanghae H. Optimal background colour for rearing Asian seabass (Lates calcarifer). Aquac Res. 2020; 51:1743-52

28.

Saoud IP, Mohanna C, Ghanawi J. Effects of temperature on survival and growth of juvenile spinefoot rabbitfish (Siganus rivulatus). Aquac Res. 2008; 39:491-7

29.

Smith KE, Burrows MT, Hobday AJ, Sen Gupta A, Moore PJ, Thomsen M, et al. Socioeconomic impacts of marine heatwaves: global issues and opportunities. Science. 2021; 374:eabj3593

30.

Sun L, Chen H. Effects of water temperature and fish size on growth and bioenergetics of cobia (Rachycentron canadum). Aquaculture. 2014; 426-427:172-80

31.

Sun L, Chen H, Huang L. Effect of temperature on growth and energy budget of juvenile cobia (Rachycentron canadum). Aquaculture. 2006; 261:872-8

32.

Tamazouzt L, Chatain B, Fontaine P. Tank wall colour and light level affect growth and survival of Eurasian perch larvae (Perca fluviatilis L.). Aquaculture. 2000; 182:85-90

33.

Tewksbury JJ, Huey RB, Deutsch CA. Putting the heat on tropical animals. Science. 2008; 320:1296-7

34.

Villamizar N, Blanco-Vives B, Migaud H, Davie A, Carboni S, Sánchez-Vázquez FJ. Effects of light during early larval development of some aquacultured teleosts: a review. Aquaculture. 2011; 315:86-94

35.

Wang CA, Li JN, Wang LS, Zhao ZG, Luo L, Du X, et al. Effects of tank colour on feeding, growth and stress responses of young taimen Hucho taimen (Pallas, 1773). J Appl Ichthyol. 2016; 32:339-42