White Tanks Research Articles

Rearing American bullfrog tadpoles in different tank colors: Effect on metamorphosis, performance, and biochemistry responses

This study examined the influence of tank color on the performance, time to metamorphosis, skin pigmentation, and biochemistry parameters of American bullfrog tadpoles and froglets. Six hundred tadpoles (0.94 ± 0.11 g) were selected (Gosner stage – 25) and distributed in a completely randomized design in 15 tanks of 40 L (1 tadpole L−1) in a recirculating aquaculture system, five repetitions of each color (blue, black, and white). Biometrics were performed every 14 days in all experimental units, and when the tadpoles at metamorphic climax and following complete transformation. Animals were weighed, measured, and photographed to evaluate the growth performance, uniformity, and skin pigmentation analyses. At the conclusion of metamorphosis, twenty-four animals randomly selected per treatment were euthanized. Twelve of them were macerated to performed of the whole-body biochemistry analysis, and the other twelve were dissected to obtain the biological indexes. The tadpoles raised in blue, and black tanks reached the metamorphosis climax and transitioned into froglets more rapidly (P < 0.05) than animals held in white tanks. However, tadpoles at metamorphic climax reared in black tanks had prolonged time to complete the metamorphosis (P < 0.05). The tadpoles raised in blue background had the higher values for final body weight throughout the experiment (P < 0.05). The tadpoles raised at blue and black tanks had the higher values for body weight gain, body length, body length gain, protein efficiency ratio, specific growth rate and lower feed conversion ratio throughout the experiment (P < 0.05). The pre- and pro-metamorphic uniformity of tadpoles was affected by the color of the tank, with the white treatment having lower uniformity at the 14, 42, 56, 70 and 98 days of the experiment (P < 0.05). In addition, tadpoles on metamorphic climax and froglets raised on black, and blue tanks had darker color of skin compared with the animals raised in white tanks, with animals raised in black tanks showing darker skin tones (P < 0.05). However, neither the growth, and uniformity of tadpoles on metamorphic climax and froglets, nor the biological indexes and whole-body biochemistry of froglets were affected by tank color (P > 0.05). Therefore, considering the homogeneity in growth, and time to metamorphosis, blue colored tanks represent best choice for reared of American bullfrog tadpoles.

Effects of Background Color on Growth, Stress, Biochemical, Hematological, and Immunological Responses, and Expression of Growth-Related Genes in Oscar Fish (Astronotus ocellatus)

The aim of the current study was to assess the impacts of tank color on the growth, stress, biochemical, hematological, and immunological responses, and expression of growth-related genes in juvenile Oscar (Astronotus ocellatus). Therefore, a total of 120 fish (9.14 ± 0.34 g) were distributed into 12 aquariums (60 × 50 × 35 cm) and divided into four treatments (aquariums with blue, white, yellow, and red colors) in three replicates (10 fish per aquarium). The fish were daily hand-fed ad libitum in three meals at 7:00, 12:00, and 17:00 hr for 56 days. Results showed that Oscar fish cultured in the red aquariums had higher final weight and weight gain and lower feed conversion ratio. Plasma cortisol, glucose, and lactate values of fish were significantly higher, and the amount of white blood cells was lower in the blue aquariums compared to other tank colors. Plasma triglyceride values were significantly higher in the white and yellow groups than the blue aquariums. Moreover, fish cultured in yellow and red aquariums had significantly higher melatonin levels than the blue aquariums. Plasma cholesterol, total protein, albumin, complement 3, and total immunoglobulin values were highest in Oscar fish cultured in the red aquariums. Also, lysozyme and alternative complement (ACH50) activities and complement 4 values of fish cultured in yellow and red aquariums were meaningfully higher compared to blue and white groups. Growth hormone relative gene expression levels were meaningfully higher in Oscar fish cultured in white, yellow, and red aquariums than the blue aquariums. Furthermore, insulin-like growth factor-1 (IGF-1) relative gene expression levels were significantly higher in fish cultured in yellow and red aquariums compared to those cultured in blue and white tank colors. Thus, the most suitable tank color for rearing juvenile A. ocellatus is red, while blue tank color is unsuitable.

Functional relation of agouti signaling proteins (ASIPs) to pigmentation and color change in the starry flounder, Platichthys stellatus

We investigated the involvement of agouti-signaling proteins (ASIPs) in morphological pigmentation and physiological color change in flatfishes. We isolated ASIP1 and 2 mRNAs from the skin of starry flounder (Platichthys stellatus), and compared their amino acid (aa) structures to those of other animals. Then, we examined the mRNA expression levels of two ASIPs (Sf-ASIPs) in the pigmented ocular body and in the unpigmented blind body, as well as in the ordinary skin and in albino skin, in flatfishes. To investigate the role of Sf-ASIPs in physiological color change (color camouflage), we compared the expression of the two genes in two background colors (dark-green and white). Sf-ASIP1 cDNA had a 375-bp open reading frame (ORF) that encoded a protein consisting of 125 aa residues, and Sf-ASIP2 cDNA had a 402-bp ORF that encoded a protein consisting of 132 aa residues. RT-PCR revealed that the strongest Sf-ASIP1 and Sf-ASIP2 expression levels were observed in the eye and blind-skin, respectively. In Sf-ASIP1, the gene expression did not differ between the ocular-side skin and blind-side skin, nor between ordinary skin and abnormal skin of the fish. However, in Sf-ASIP2, the expression level was significantly higher in blind-side skin, compared to ocular-side skin, suggesting that the ASIP2 gene is related to the countershading body pigment pattern of the fish. In addition, the Sf-ASIP2 gene expression level was lower in the pigmented spot regions than in the unpigmented spot regions of the malpigmented pseudo-albino skins on the ocular side, implying that ASIP2 is responsible for the ocular-side pseudo-albino. Additionally, ASIP2 gene expression in the blind-side skin of ordinary fish was enhanced by a white tank, implying that a bright background color could inhibit hypermelanosis in the blind-side skin of cultured flounder by increasing the activity of the Sf-ASIP2 gene. However, we did not find any relationship of ASIPs with camouflage color changes. In conclusion, the ASIP2 gene is related to the morphological pigmentation (countershading and malpigmentation) of the skin in starry flounder, but not with physiological color changes (color camouflage) in the ocular-side skin.

Influence of Culture Tank Colours on the Water Quality, Growth Performance and Feed Utilization of Oreochromis niloticus (Linnaeus, 1758) Juveniles

The study was conducted over a period of fifty-six (56) days to investigate the effects of different colours of culture tanks on the water quality, growth, and feed utilization of Nile tilapia (Oreochromis niloticus) juveniles. O. niloticus of mean body weight of 8.5g were stocked and fed twice daily with a commercial diet containing 42% crude protein. The experiment had four treatments based on tank colours; white, green, black and blue coloured tanks. Some water quality indices were assessed once in a week while the fish were weighed at the end of the experiment to compute the performance indices. The data were presented using mean and standard error and comparative analysis was done using one way ANOVA at 95% confidence interval with Duncan multiple range test as the follow up test. The water quality parameters examined during the study were not significantly different among the treatments. All the selected water quality parameters were within the acceptable range for tropical fish culture. While there was no significant difference in final weight, weight gain, percentage weight gain, and specific growth rate among the treatments, black tanks showed slightly higher values with 10.89±0.89 g, 2.54±0.94g, 30.47±11.43%, and 0.47±0.16%/day, respectively. Higher feed intake and FCR were recorded in green tank (10.08±0.61 g and 7.92±2.70 respectively) and the least was observed in black tank (9.32±0.12g and 4.23±1.51). The percentage survival of the fish was different significantly among the treatments (P&lt;0.05). Fish reared in white background showed the highest survival (100%) which was different significantly from all other treatments. The blue and black tanks showed slightly higher values of viscerosomatic index and hepatosomatic index with 7.22±1.00% and 2.02±0.25%, respectively, while black and white tanks had the least values with 4.44±1.11% and 1.64±0.15%, respectively. The results showed that O. niloticus juveniles can be reared in all the tanks with no negative implication on their performances. However, black and white tanks showed better potential towards improved growth and feed utilization, while white tank led to better survival rate and tended towards better well-being as indicated by the skin pigmentation and hepatosmatic index. Therefore, rearing of O. niloticus juvenile in white tank is recommended over other colours.

Tank color influences the response of tomato clownfish (Amphiprion frenatus) to an acute stress challenge.

The trade of aquarium organisms is growing worldwide. This market depends on a continuous supply of healthy and colorful aquatic animals, but this sector has few initiatives. However, in the last decade, there has been a growing interest in researching captive breeding of these animals, aiming to develop a more sustainable aquarium hobby. Larviculture is an important phase in the cultivation process because the larvae are more sensitive to stress and variations in the bulk of variables, such as temperature, salinity, nutritional management, light intensity and spectrum, and environmental background colors. Because background color could be a promoter variable of proper welfare, we tested whether it affects the endocrine response of tomato clownfish Amphiprion frenatus larvae to an acute stress challenge. We show that background color influences the endocrine stress axis responsiveness in tomato clownfish. When fish were subjected to a standard acute stressor of 61 days after hatching, only fish adapted to white walls increased the whole-body cortisol levels. From the results presented herein, we recommend that white tanks be avoided for A. frenatus larviculture. Both, the less stress level and the good welfare condition of larvae reared in colored tanks may have robust, practical applications since almost all clownfish in the ornamental aquarium trade come from captive breeding.

Young Women and Disgust in Contemporary Norwegian Comics: A Close Reading of Ane Barstad Solvang's Frykt &amp; medlidenhet

Young Women and Disgust in Contemporary Norwegian Comics: A Close Reading of Ane Barstad Solvang's <i>Frykt</i> &amp; <i>medlidenhet</i>

Does tank background colour influence the growth, survival, and carotenoid content in fishes? An illustration in filament barb, Dawkinsia filamentosa (Valenciennes, 1844)

The various environmental factors have a significant impact on cultured species. One such factor influencing larval production in finfish hatcheries is the tank colour. The current study appraised at how different background tank colours such as white, red, blue, green, and black influenced the growth, survival, and body pigmentation of filament barb, Dawkinsia filamentosa. The experiment was conducted for 30 days and the fish were fed with powdered diet thrice a day containing 30% crude protein and 4% crude lipid at satiation level. At the end of study, it was found that the final body length in the black colour tank (15.33 ± 0.17 mm) was significantly (p < 0.05) higher compared to other tank colour groups. In comparison to other treatments, the final body weight (65.17 ± 1.48 mg) and average daily weight gain (1.56 ± 0.05 mg day−1) in the black colour tank was found to be significantly (p < 0.05) higher, while the white colour tank (35.83 ± 1.64 mg; 0.59 ± 0.06 mg day−1) were significantly (p < 0.05) lower. The fish reared in the black colour tank had significantly (p < 0.05) higher specific growth rate (4.22 ± 0.07% day−1) and thermal growth coefficient (19.4 ± 0.6), whereas the white colour tank had the lowest (SGR = 2.24 ± 0.17% day−1; TGC = 7.27 ± 0.71). The survival rate was significantly (p < 0.05) higher in black colour tank (78.33 ± 1.67%) and lowest survival was observed in white tank colour (56.67 ± 3.33%), which represented an improvement of almost 20% for the fishes reared in black colour tank. Fish reared in black tank had the significantly higher level of carotenoid content (2.33 ± 0.08 μg g−1) and fish reared in white tank had lower body carotenoid level (1.02 ± 0.05 μg g−1). It was observed that the different tank colour did not (p > 0.05) cause any change in the stress and non-specific immune parameters of filament barb. Based on the findings, it can be stated that black background colour is the best tank colour for rearing and production of filament barb.

The Idea of Ancestors

The Idea of Ancestors Sue Churchill (bio) After Ethredge Knight My father bobs down the river of ancestors,drifts in darkness where our lights dot the shore. In the sky white pocket handkerchiefs lie crumpled;white tank trucks and barges, white tank carsroll from a chemical plant on high. Below,the river carries his lifetime of shoveled dirt,his black coffee, unfiltered cigarettes. My father knows I disdain him and all his people.I am none of them. They are none of me.He knows the river is dark and cold and dirty.He knows the little he has always had to offer. Oh my yellow-eyed father, yellow-eyed as I am,when I enter the water, I will not be denied. [End Page 105] Sue Churchill A former teacher, Sue Churchill currently works in farming, managing a farm and raising a flock of sheep in Woodford County, Kentucky. She grew up in Breckinridge County, and her work is strongly influenced by the rural setting of her life, past and present. Copyright © 2022 Berea College ...

Effect of background tank color in combination with sand substrate and shelters on survival and growth of Scylla tranquebarica instar

Effect of tank color in combination with substrate-shelters on the survival and growth of the instar of purple mud crab, Scylla tranquebarica (initial body weight of 28.7 ± 2 mg) was investigated. Ten treatments were tested in triplicate with black (B) and white (W) tanks were set as the control, while other tanks were provided with a combination of sand substrate (S), and/or polyvinyl chloride pipes (P) as horizontal and nets (N) as vertical shelter, referred as B, BS, BSP, BSN, BSPN, W, WS, WSP, WSN and WSPN, respectively. Survival of the instar in black tanks (26.7 to 60.0%) was higher than in white tanks (20.0 to 46.7%) (P = 0.052). Survival in the horizontal shelter treatments (46.7 and 63.3%) exceeded that in the vertical shelter groups (30.0 and 50.0%) (P = 0.068). The final body weight of the instar in black tank (2.4 to 3.8 g) was significantly lower than white tank (2.6 to 4.8 g) (P = 0.02). Specific growth rate was significantly greater in sand substrate treatments (8.4 to 9.1%/day) than in controls (7.9 and 8.0%/day) (P = 0.015). In conclusion, horizontal shelter was better than vertical type, and black tank with substrate and horizontal shelter was more suitable for culture of purple mud crab instar.

Effects of tank color on the growth, survival rate, stress response, and skin color of juvenile hybrid catfish (Clarias macrocephalus × Clarias gariepinus)

This study focused on the effects of tank color on the growth, survival rate, stress response, and skin color of juvenile hybrid catfish (Clarias macrocephalus × Clarias gariepinus) reared in tanks of 5 different colors (white, red, green, blue, and black). Experiments were performed in triplicate with a duration of 8 weeks. Growth performance, feed utilization efficiency, survival rates, stress levels (as indicated by hematocrit, blood glucose, and plasma cortisol levels), and skin color parameters were evaluated in this study. Fish reared in red tanks exhibited a significantly higher mean final body weight (FBW) (27.50 ± 0.26 g), greater weight gain (WG) (18.57 ± 0.30 g), and a higher specific growth rate (SGR) (2.08 ± 0.03% per day) than those reared in tanks of other colors (P < 0.05). In addition, fish reared in red tanks had the lowest mean feed conversion ratio (FCR) (1.23 ± 0.05), which was significantly different from those reared in green (1.86 ± 0.10), blue (1.88 ± 0.04), and black (1.88 ± 0.16) tanks (P < 0.05). Fish reared in red (95.55 ± 2.22%) and blue tanks (95.56 ± 4.44%) had higher survival rates (SR) than fish reared in white (93.33 ± 3.85%), green (84.44 ± 5.88%), and black (80.00 ± 3.85%) tanks. The survival rates of fish reared in red and blue tanks were significantly higher than those reared in black tanks (P < 0.05). The stress indicators revealed the highest levels of hematocrit for fish reared in green tanks (41.80 ± 2.26%), followed by those reared in black (37.86 ± 2.19%), blue (37.76 ± 4.24%), red (36.38 ± 2.39%), and white (31.06 ± 4.45%) tanks. Of these, the fish reared in green tanks had a significantly higher mean hematocrit level than those reared in white tanks (P < 0.05). The plasma cortisol levels of fish reared in red tanks (18.73 ± 4.48 nmol/L) were lower than those reared in tanks of other colors. The skin color of fish reared in white tanks was the lightest (grayish–brown and yellowish–white), followed by fish reared in red, green, blue, and black tanks, which had the darkest skin color (black). This study demonstrated that the lightness (L*) of the tank color had an effect on fish skin color (74%). The assessment of growth performance, feed utilization efficiency, survival rate, stress responses, and skin color indicated that red is the most appropriate tank color for rearing hybrid catfish.

Effect of tank colour on growth, survival, stress level, digestive enzymatic activities and body composition of snubnose pompano ( Trachinotus blochii Lacépède) larvae

Snubnose pompano (Trachinotus blochii, Lacépède) is a commercially important fish species that shows robust growth in captive environment. Tank colour is an important factor affecting the growth of fish larvae in aquaculture. Although the effect of tank colour has been studied in several fish species, it has not been studied in the snubnose pompano. We aimed to investigate how tank colour affects overall growth, survival, body composition, stress levels and digestive enzyme activities of snubnose pompano larvae at early larval stage and late larval stage. We noted that early–larval–stage larvae showed higher growth, crude protein contents and lower digestive enzyme activities when reared in blue and white tanks. Larvae showed low-stress levels when reared in grey and blue tanks. The same larvae showed low-survival and high-stress levels when reared in red tanks. The late–larval–stage larvae showed high growth and lipids, and low-digestive enzymes activities in white and yellow tanks. The larvae showed high-stress levels and low-ash contents when reared in red tanks. These differences are most likely due to the differences in light intensity inside tanks, which affects the ability of larvae to find and catch prey. Overall, our study sheds new light on cultivation conditions for snubnose pompano larvae. We recommend blue tanks for growing early–larval–stage larvae and white or yellow tanks for late-larval-stage larvae.

An evaluation of the growth-promoting effects of green light on spotted halibut for its practical application in aquaculture

We examined the effects of tank color and stocking density on the growth of spotted halibut (Verasper variegatus) under a green light-emitting diode (LED). Fish reared for 40 days under a green LED (10 μmol m–2 s–1 at the water surface) grew faster than those reared under a white LED, irrespective of tank color (white or black). Green light promoted higher growth than indoor room light when fish were kept for 32 days under both the tested stocking densities, 4.3 kg m–2 and 13 kg m–2, but stocking density alone did not affect fish growth. These results suggest that a growth-promoting effect of green light can be expected within the range of stocking densities applied here for fish housed in both black and white tanks.

Morphological colour adaptation during development in fish: involvement of growth hormone receptor 1

Morphological background adaptation is both an endocrine and a nervous response, involving changes in the amount of chromatophores and pigment concentration. However, whether this adaptation takes place at early developmental stages is largely unknown. Somatolactin (Sl) is a pituitary hormone present in fish, which has been associated to skin pigmentation. Moreover, growth hormone receptor type 1 (Ghr1) has been suggested to be the Sl receptor and was associated with background adaptation in adults. In this context, the aim of this work was to evaluate the ontogeny of morphological adaptation to background and the participation of ghr1 in this process. We found in larval stages of the cichlid Cichlasoma dimerus that the number of head melanophores and pituitary cells immunoreactive to Sl was increased in individuals reared with black backgrounds compared with that in fish grown in white tanks. In larval stages of the medaka Oryzias latipes, a similar response was observed, which was altered by ghr1 biallelic mutations using CRISPR/Cas9. Interestingly, melanophore and leucophore numbers were highly associated. Furthermore, we found that somatic growth was reduced in ghr1 biallelic mutant O. latipes, establishing the dual function of this growth hormone receptor. Taken together, these results show that morphological background adaptation is present at early stages during development and that is dependent upon ghr1 during this period.

Cultivation of juvenile Colossoma macropomum in different colored tanks in recirculating aquaculture system (RAS): Effects on performance, metabolism and skin pigmentation

This study assessed the effects of different tank colors (white, blue, green and black) on the performance, metabolism and skin pigmentation of Colossoma macropomum cultivated in recirculating aquaculture system (RAS). In Phase 1 of the experiment, 224 juvenile C. macropomum (4.04 ± 0.32 g) were cultivated for a period of 30 days at a density of 0.5 juveniles/L. In Phase 2 of the experiment, the juveniles (34.32 ± 12.14 g) were cultivated within each treatment for another 20 days at a density of 0.25 juveniles/L. Biometrics were performed for all juveniles after 30 and 50 days of cultivation. Blood was also collected after 50 days of cultivation and skin pigmentation analysis and determination of the hepatosomatic index (HIS) and lipid concentration in the liver (HL) were performed. Juveniles grown in white tanks had the highest final weight (FW), total length (TL) and weight gain (WG) among treatments at the end of the both phases. At the end of Phase 2, juveniles grown in white tanks had higher levels of triglycerides (p < 0.05) than juveniles of the other treatments. Juveniles grown in black tanks had darker pigmentation and higher hemoglobin and total plasma protein (p < 0.05) than the other treatments. Tank color was found to affect the performance, pigmentation and metabolism of juvenile C. macropomum cultivated in RAS, with white tanks providing the best environment for cultivation and welfare.

Insights into first feeding of newly-hatched paralarvae of the merobenthic octopus, Octopus tetricus

The commercial aquaculture of merobenthic octopus species is constrained by the inability to raise large numbers of paralarvae through their planktonic phase from hatching to juvenile. Knowledge on the early feeding behaviour and nutrition requirements of octopus paralarvae is critical for addressing this challenge. This study evaluates the food seizure behaviour of Octopus tetricus paralarvae at age 0–5 dph (days post-hatch) under different experimental conditions including, egg incubation method, tank colour, and live prey versus formulated food pellets. The percentage of paralarvae that attacked food items and the percentage of paralarvae that had at least one successful seizure at the age 0–5 dph were measured in relation to the experimental conditions. The number of attacks and successful seizures of food items by paralarvae was not affected by the egg incubation method, i.e., maternal grooming versus artificial incubator tank. A higher percentage of paralarvae performed attacks in black tanks (70 ± 8%) compared to grey tanks (44 ± 6%) with no differences to white tanks (58 ± 7%) when Artemia nauplii were supplied. However, no differences in the proportion of paralarvae with successful seizures were found among the three tested tank colours. A higher percentage of paralarvae attacked formulated food pellets (69 ± 6%) compared to Artemia nauplii (44 ± 6%) in grey tanks. An overall trend was observed of O. tetricus paralarvae having lower successful seizures at 0 dph that increased until 2 to 3 dph followed by a steep and continuously decline in success through until 5 dph. On average 31 ± 3% of paralarvae had at least one successful seizure of formulated food pellets in the first 5 min after the pellets were supplied compared to 4 ± 1% in the subsequent 10 min. In contrast, feeding on Artemia nauplii remained steady over the full 15 min experimental period. The results indicate that the effect of tank colour on feeding behaviour warrants further investigation as it affects the ability of the paralarvae to detect and attack potential food items. Moreover, the results demonstrate that artificial egg incubation did not have a negative effect on the feeding behaviour of paralarvae, and that formulated food pellets have the potential to be developed as an alternative to live prey for the culture of paralarvae of this species.

Variety of Tank Colours to Enhance the Colour Quality of Platyfish (Xyphophorus helleri)

One of the factors that affect the colour quality of the platy fish (Xyphophorus helleri) during cultivation is the environment in bright light conditions, where setting bright light conditions can be done using a tank with a colour that can absorb light. Therefore, a study was conducted to examine the effect of tank colour on improving the colour quality of the platy fish and determining the correct tank colour. This research was conducted with an experimental method using a completely randomized design (CRD) consisting of five treatments repeated three times. The colour treatments of the tanks used were white, black, red, orange and yellow. The parameters observed were the increase in colour, growth in absolute weight and length and survival rate of platy fish. The results showed that the use of different tank colours had a significant effect (p &lt;0.05%) on the improvement of colour quality and growth in absolute weight, and had no significant effect (p&gt; 0.05) on absolute length growth and survival rate. The highest increase in colour quality was in white tanks with brightness values ranging from 13-15% and absolute weight growth ranging from 0.21 to 0.25 g. Therefore, in the cultivation of platy fish, a white tank should be used.

Effects of Tank Colour on Body Colour Intensity and Growth of Yellow Gourami Trichopodus trichopterus

Yellow gourami (Trichopodus trichopterus) is a species native to Southeast Asia and is famous as ornamental species. However, hobbyists and farmers encounter problems where its body colour easily becomes faded in captivity. Since colour enhancer pellets are expensive, an experiment was performed to determine whether tank colour can influence the body colour intensity and growth of T. trichopterus. Four different tank colours (white, yellow, blue and green) with five replicates were tested where fish were kept under natural lighting (outdoor) conditions for two months. The results demonstrated that fish reared in green coloured tank showed an increment in its colour intensity while fish reared in white tanks increased its body weight. It can be concluded that tank colour does affect the body colour intensity and weight of T. trichopterus. This study will help farmers and hobbyists to solve colour fading problem using a cheaper way.

The effects of the tank colour on growth performance and physiological responses in fingerling grouper, Epinephelus coioides

In this study, the effects of different background colours on growth performance and physiological parameters of Epinephelus coioides were investigated. One hundred eighty E. coioides (average weight 18.16 ± 0.07 g) were distributed in black, white and blue 300-L tanks and fed to satiation for 60 days. The tank colour had no significant effect on the weight gain, condition factor, hepatosomatic index and specific growth rate (p > .05). The lowest amount of viscerosomatic index and the highest carcass protein were recorded in the white tank (p < .05). Daily food intake, feed conversion ratio and plasma glucose were significantly higher in the blue tank (p < .05). The highest levels of haematocrit and plasma triglyceride were observed in the white tank, while the total protein and albumin were higher in the black tank compared to the other tanks. The tank colour had no significant effects on the plasma cortisol level (p > .05). Our findings showed that colours used in this study did not evoke stress and thus had no effect on growth, but some metabolic adaptation occurred in each colour to achieve optimum growth.

Comparison on growth performance, body coloration changes and stress response of juvenile river catfish, Pangasius hypophthalmus reared in different tank background colour

The effects of different tank background colours (green, black and white) on the growth performance and body coloration of juvenile river cafish, Pangasius hypophthalmus, were examined in this study. The experimental fish with an initial body weight (BW) 0.13 ± 0.05 g and total length (TL) 2.54 ± 0.37 cm were used, and groups of 15 fish per tank were randomly distributed. The experiment was conducted for 20 days as a triplicate for each treatment. Survival, growth in BW, body weight gain (BWG), total length (TL), total length gain (TLG), specific growth rate (SGR), condition factor, feed conversion ratio (FCR), swimming speed, body coloration and stress response were evaluated. River catfish reared in white and green tanks attained significantly higher BW, BWG, TL, TLG and SGR compared to the black tank. The white tank attained significantly better FCR compared to the black tank. River catfish showed the most active swimming behaviour in the green tank (5.49 ± 1.32 cm/s) while the least in the white tank (3.37 ± 0.93 cm/s). Body coloration of river catfish in the black tank showed almost pure black body coloration (75.59 ± 9.08), followed by the green tank (126.23 ± 17.46) and the white tank (148.19 ± 10.51). However, there was no significant difference in the stress level of river catfish reared in white and black tanks and insignificant to those reared in the green tank. The findings in this study showed that the white and green background colour tanks can be used for promoting growth of river catfish culture while the black background colour tank can enhance body coloration that is suitable as ornamental fish.

Oxidative Status and Digestive Histology of Barramundi Perch in Response to Different Tank Colors.

The oxidative status and intestinal and liver histology of Barramundi Perch Lates calcarifer juveniles were investigated in an experiment using different tank colors (black, red, blue, and white) over 6weeks. It has been previously shown that background color can affect physiological processes in different species. The background colors did not cause significant differences in malondialdehyde, catalase, or glutathione S-transferase, whereas superoxide dismutase and glutathione peroxidase activities were significantly higher in fish that were kept in black tanks. Plasma cortisol of fish adapted to blue and white tanks was significantly lower than that of fish in black tanks. The liver total antioxidant capacity was highest for fish that were maintained in white and blue tanks. The results of histopathological evaluation revealed that tank colors did not have significant effects on intestinal mucosal and enterocyte dimensions. No specific alterations were found in the liver or intestine of fish relative to the tank background color during the experimental period. In conclusion, white and blue tanks resulted in improved oxidative status of Barramundi Perch juveniles.