Black Tanks Research Articles

EFFECTS OF COLOUR OF CULTURE FACILITY (TARPAULIN) ON GROWTH PERFORMANCE & SURVIVAL OF Clarias gariepinus

It is important to note if the different colours of tarpaulin used for culture have effect on the growth performance and survival of Clarias gariepinus. The study was carried out in faculty of Agric cooperative farms located at Evboneka, Ovia North East local government area, Edo state. The research was designed as a factorial experiment made up of 3 colours of tarpaulin tanks (black, yellow and brown) x 18 weeks culture period in CRD. Each treatment replicated trice. Thus a total of nine culture units was used. The experimental unit was made up of 3 black, 3 brown and 3 yellow tarpaulin tanks each measuring 4x5m2. 2700 post fingerlings that is, 300 post fingerlings/tank were bought from a reputable hatchery and cultured for 18 weeks under semi-intensive system (10 fish/m2). The yellow tarpaulin tank had the highest mean weight (283.21g) followed by the black tarpaulin tank (247.964g) and brown tarpaulin tanks (249.42g) (P.<0.05)). The result also showed that fishes in yellow tanks had better FCR of 1.220) followed by brown tanks with 1.236 and black tarpaulin tanks with 1.251 as FCR. However, percentage survival was slightly higher in Black tanks (89.63), followed by the brown (89.30) and the lowest in the yellow tanks (88.86). This study showed that colour of culture facility may slightly affect fish growth and yield. Yellow tarpaulin tank appears to be brighter in colour and had relatively higher weight gain and is therefore recommended for C gariepinus culture over other tank colours (Black and brown).

Impact of the Color of Rearing Tank on Behavior and Growth of Nile Tilapia, Oreochromis niloticus (Linnaeus, 1758)

This study examined the impact of tank color (black, red, blue, green, and transparent) on the behavior (boldness and aggressiveness) and growth of Nile Tilapia over nine weeks (first, third, sixth, and ninth weeks). Boldness and aggression levels were assessed using open field and mirror image tests, respectively, for individual Nile Tilapia (Oreochromis niloticus). Healthy Nile Tilapia, initially weighing 2.51g on average, were used in the experimental trials conducted in tanks of different colors. The findings indicated that red tanks appeared to foster the highest level of boldness (p<0.05), whereas fish in transparent tanks exhibited the highest level of aggressiveness compared to other tanks (p<0.05). Moreover, individuals in black tanks displayed the highest growth rate in terms of weight (p<0.05). This study suggests that Oreochromis niloticus can thrive better in black-rearing tanks, as the black tanks appear to enhance the growth rate of the fish, possibly through improvements in physiological processes.

Lignin extraction in chemical pulp mills: The role of flexible operation

Lignin extracted from black liquor in chemical pulp mills can potentially replace fossil carbon feedstocks in fuels and materials, thereby increasing the economic and environmental added values of woody biomass. However, since lignin extraction reduces the electricity generation of the mill, the added value depends on the characteristics of the electricity market in which the mill operates. In this study, a model mill is exposed to two different electricity price profiles: the low and steady prices of south-central Sweden in Year 2019; and the high and volatile prices of the same region in Year 2022. For the model mill, investments in lignin extraction designed to increase pulp production are economically viable and have low levels of sensitivity to electricity price levels and price volatility. The viability of lignin extraction without increased pulp production depends on the relationship between the electricity and lignin prices. With stable electricity prices, or steady mill operation, a rule-of-thumb holds that for lignin extraction to be viable, the lignin price (€/t) must be 1.8-times the average electricity price (€/MWh) plus 40 €/t for the supply of chemicals. With volatile electricity prices and flexible operation of the recovery boiler, the mill can shift the loss in electricity sales to low-price hours, thereby saving 15–70 % of the operational costs of lignin extraction, as compared to steady operation. This effect can be further enhanced by increasing the capacity of the lignin extraction process or extending the size of the black liquor storage tank. The proposed flexibility measures allow the market-integrated pulp mill to export lignin to replace fossil carbon supplies in other sectors, while supporting the electricity system during hours with high demand and low supply.

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 Dietary Taurine on Maturation Indices, Antioxidant Capacity, Ovaries Amino and Fatty Acids Profile, and Vitellogenin Gene Transcription Level in Penaeus vannamei Female Brooders

A 30‐day research was carried out to examine the impacts of dietary taurine (Tau) on ovaries maturation and physiological responses of Penaeus vannamei female brooders (29.4 ± 0.2 g). A basal diet (497 g kg−1 protein and 140 g kg−1 lipid) was administered with graded levels of Tau ranging from 0 (control) to 2, 4, 6, 8, and 10 g kg−1. A total of 180 shrimp brooders were stocked into 18 250 L black circular polyethylene tanks. Female (n = 5) and male (n = 5) shrimps were stocked in each tank and supplied with seawater (35.2 ± 3.1 g L−1 salinity, 28.9 ± 1.4°C) and the experimental feeds were offered to shrimp twice a day at 5% of their biomass. Supplementing diet with 4–8 g Tau kg−1 reduced latency period after eye stalk ablation to spawning (5–6 days) that was associated with higher hepatopancreatic and gonadosomatic (except for 8 g Tau kg−1 diet) indices (p &lt; 0.05). With 10 g Tau kg−1 diet hepatopancreas glutathione peroxidase activity and total antioxidant capacity increased and catalase activity increased by 6 g Tau kg−1 diet. Supplementing diet with Tau‐enhanced bile‐salt dependent lipase activity in the gut. Docosahexaenoic acid and Tau levels were elevated in the ovaries with the increment of dietary Tau level (p &lt; 0.05). Plasma total protein, calcium, cholesterol, and high‐density lipoprotein increased with inclusion of 6–10 g Tau kg−1 diet. The transcription levels of vitellogenin, insulin-like growth factor II, superoxide dismutase, prophenoloxidase, and lysozyme genes transcription levels were upregulated in the hepatopancreas of shrimp brooders fed 6–10 g Tau kg−1 diet (p &lt; 0.05). It seems that Tau at 4–8 g kg−1 diet by modulating lipid metabolism, antioxidant capacity, and immunocompetence can improve maturation and health status of P. vannamei brooders.

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.

Suitability Assessment of Two Different Culture Systems for the Rearing of Clarias gariepinus Fingerlings

This paper presents an experiment in which two different fish culture system types were evaluated for the short-term commercial culture of fingerlings of Clarias gariepinus maintained at half the recommended stocking rate; 82.5/m3 in 2 m3 water volume in indoor blue fiber-glass tanks (IFT) and outdoor black plastic tanks (OPT). The research objectives were to assess the suitability and commercial viability of the tanks. Initial mean body weight of graded fingerlings of C. gariepinus for IFT and OPT were 11.32±2.25 g and 10.92±2.44 g (mean±standard deviation) respectively. The study lasted for eight weeks with the fish attaining post-juvenile sizes of 174.95±74.30 g and 178.84±52.04 g (mean±standard deviation) in the IFT and OPT respectively which were not significantly different at p &gt; 0.05. Survival at termination was 81.21±0.0% and 81.21±2.5% for IFT and OPT respectively. As fish attained larger sizes of 100 g and above between weeks 6 and 8, skin lesions and frayed fins were observed in comparatively more of the indoor reared fish than the outdoor reared fish. It may be concluded that the systems are not vastly different in terms of resultant survival and growth performance of the African catfish, however, the culture duration may be halved when maintaining the reported stocking rate in order to prevent distress as a fallout of aggression as they increase in size.

The Effect of Background Color on Skin Color Variation of Juvenile Plectropomus leopardus.

Fish skin color is usually strongly affected by the background color of their environment. The study investigated the effects of five different background colors on the skin color of leopard coral groupers (Plectropomus leopardus). More than 450 juveniles were reared in Blue, Red, Black, White, and Transparent background tanks for 56 days. The paraffin section showed that the skin melanin zone of fish in the White group was smaller, whereas the Black and Red groups (especially Black) were nearly the largest. The apparent skin color of P. leopardus was red on the white background, which darkened in response to the other color backgrounds. The Black group revealed the blackest skin color, followed by the transparent group. Moreover, the White group had the highest L*, a*, and b* values. The melanin content and tyrosinase activity in the dorsal and ventral skin of the Black group were significantly higher than those in the other groups (p < 0.05), and the serum α-MSH level was higher in the Black group as well. The carotenoid and lutein contents showed completely different trends among the experimental groups, as carotenoid content was higher in the Red and White groups, while lutein content was higher in the Transparent group. The expression level of scarb1 was highest in the Blue and White groups, followed by the Transparent group, and lowest in the Black group (p < 0.05). The expression trend of scarb1 was similar to the skin color in different backgrounds, indicating that the background color regulated scarb1 expression level through visual center, then influenced the uptake and transport of carotenoids, then influenced the skin color formation of P. leopardus. Moreover, lighter colors inhibited the formation of melanocytes and had a significant effect on carotenoid and lutein contents. Pigment-related genes were involved in the regulation of fish skin color, and they were affected by background color in P. leopardus. These results indicate that a white background is more conducive to maintaining red skin color in juvenile P. leopardus.

K2 전차 흑표의 수출시장 다변화를 위한 수출경쟁력 평가 지표의 가중치 산정에 관한 연구

Considering that the K2 tank black panther tank export contract with Poland in recent days is a prime mover to advanced defense countries, it is a point of great interest for the future. The K2 tank black panther tank shows the highest export performance as a single type among Korea’s main export weapon systems. In addition, the localization rate of parts and production is very high, so stable supply chain management is also possible. To diversify potential export markets, it is necessary to evaluate the factors that enhance the export competitiveness of the K2 Black Panther from multi-dimensional perspective. This study is to recognize the potential export market diversification through export competitiveness analysis in Porter’s five forces perspective of the K2 black panther tank. Analytic Hierarchy Process(AHP) method was used in considering the factor’s weights. The survey of 14 members who participated in DAPA(Defense acquisition program administration), KRIT(Korea research institute for defense technology planning and advancement), and academic experts. The result of this study showed that the Consistency Ratio was under 0.1 in evaluation items and factors. This study implies a conceptual framework for evaluating the export competitiveness of the K2 tank black panther and provides a guideline for strategic priorities of K2 black panther on export competitive improvement factors.

Waiting to be Taken

Waiting to be Taken Carrie Hall (bio) Elysium lay sprawled on the couch like she was waiting to be taken, but nobody seemed to notice. The swooning forearm thrown casually over her brow and her knock-kneed legs falling wide apart barely caught anyone's attention. It was hard to tell if she was passed out or just weeping. Suddenly, she opened her eyes, looked around long enough to register shock and disbelief, then fell to the ground in full wail. She buried her mouth in the long red carpet and screamed. She leaned back again, her face, though dark, visibly reddened by grief. She ran her hands through her dreadlocks, now dyed blue; cheap mascara ran down all the way down her face to the two tattooed lines, like the hollows of a fiddle, on her throat. Another gutter punk, Little Bob, his head shaved bald, sat on the floor with her and cried too. When she went down for her next screaming sob, he tapped her on the shoulder and as she got up he handed her a drink—straight vodka. "Hey!" I yelled from across the room—the area partitioned as the kitchen, "put some orange juice in there!" I'd brought orange juice because I wanted people to ingest something with nutritional value and I knew I'd never be able to get anyone to eat. As one of the slightly older crowd—nineteen—I felt I had to act responsible. For punks in the early nineties, nineteen was practically middle-aged. Even still, my own drink had some juice in it, but the amount was purely symbolic; you'd have to hold it up to the light to see a thin wisp of yellow floating through the thick clear liquid. I hadn't added ice. "What the hell is she so sad about?" Max asked me. Max was Markus's wife. I mean, not wife-wife, we weren't the type of people to actually marry—not with a wedding and all that. Imagine us at a wedding; this was the way we threw a funeral. But they had a baby together, they'd just bought a house. Markus's ashes were in a plastic bag on the coffee table so everyone could come by and pay their respects. The vodka and orange juice were sitting right next to the bag. In a few hours, we'd go scatter those ashes in the river. We lived in Minneapolis, at the Mississippi's neck. "Was he fucking her?" Max said, nodding toward Elysium. Max wore black leather pants and a black tank top. Her arms were pale and strong. Her red hair, which, unlike the rest of ours, had never been dyed, was the brightest in the room. My posture was—I looked like I was going to bend in half and break under the pain of it all. Max looked like she was going to tear apart everyone in the room limb from fucking limb with her teeth. I have never seen anyone more beautiful. "Anyway he's dead now," she said. She sipped her drink (half juice) like she was at a cocktail party. I guzzled mine like water and when it was gone I was desperate for more, but I didn't dare leave her side. Everyone gave us a wide berth even though we were leaned up against the counter by the fridge, which they probably wanted to get into, but they weren't about to bother the widow— and me, whatever I was. The ghost. [End Page 325] "No really. Was he fucking her?" she asked me accusingly. In truth, I saw more of Markus than she did, because my boyfriend Johnny (where the hell was Johnny? I hadn't been able to find him all day. I'd barely seen him since Markus died) and Markus were best friends. Markus was always with us, and she was always at home with their kid, Matilda. Oh Jesus, Matilda. So I was a lot more likely to know if he was getting into trouble with that little runaway, but honestly, I didn't know for sure if Markus was sleeping with her...

A STUDY ON THE CONTINUOUS USAGE OF ORGANIC,INORGANIC PERSISTENT PESTICIDES IN THE AGRICULTURALFIELDS IN AND AROUND SIRUMALAI AREA WITH A SPECIALREFERENCE TO THE IMPACT ON GROUND WATER AND SOIL

In the present study the impact of pesticide pollution due to the discharge of pesticide waste water from the agricultural field in the Sirumalai agro lands was studied. In order to evaluate the physical and chemical parameters of water, the pond water samples, and the ground water samplesall the sides were collected and analyzed for various water quality parameters and soil parameters. The pond water is the main source of water for the bore wells located in and around the agricultural land. During the rainy season the pond water percolates into wells and bore wells. Now water is completely polluted due to percolation of pesticide waste waters which are potentially harmful, accumulation of various pesticides chemical residues in water reaches the ground water source. Bio – accumulation and bio-concentration of the pesticide waste water causes high degree of pollution. The bore wells in and around the northern side of the pond polluted with very high TDS and it is beyond redemption due to the higher limits of TDS, hardness, phosphate, ammonia and nitrate. All the water samples taken in and around the agriland are notchemically portable. The presence study reveals that the physico-chemical analysis of pond water in the pond as well as ground waters are above the permissible limit. The dissolved oxygen is analyzed and found to be deteriorated. It is due to utilization of dissolved oxygen in the water byorganic matter and by the pesticides. The investigator observed that the solar evaporation tank made of black body tank, function more effectively during summer with very high evaporationrate. The investigator found that during the normal operation period, the colour of the effluent varies and becomes clear after treatment with alum, which favours the penetration of solar energy easily and hence the efficiency of the evaporation tank increases than the normal cement slab. The advantage of utilizing the black body natural kadappa tanks for evaporation is very strong and it can absorb very high degree of solar radiation which is converted into thermal energy. The investigator observed that the solar evaporation tank made of black body tank function more effectively during summer with very high evaporation rate. The solar evaporation tank is blessed in principle of black body surface which can absorb solar radiation more effectively than ordinary cement slab.

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.

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 rearing tank colour on growth indices, blood chemistry, digestive enzymes, expression of stress and growth‐related genes of Asian sea bass juvenile ( Lates calcarifer )

The background colour of the fibreglass tanks attributed to their significant correlation with light intensity and spectrum serves as one of the major factors influencing growth performance and stress levels of cultured fish. Moreover, it plays a key role in the successful production of the cultured species, which is challenging under confinement conditions. On the other hand, Asian sea bass (Lates calcarifer) has received significant attention among researchers due to its high-profit value and growing demand in the global market. Hence, the current study was designed to investigate the effects of different tank background colours (white, red, black and blue) on growth indices, body composition, digestive enzymes, haematological parameters, expression of stress and growth-related factors in L. calcarifer. Therefore, fish (160.90 ± 6.0 g) were distributed into 12 fibreglass tanks (250-L) including four treatments in triplicates and were reared for 6 weeks. According to the present results, the highest specific growth rate was observed in fish raised in red-coloured tank followed by white and black tanks. Maximum weight gain (WG) and high protein efficiency ratio (PER) were observed in fish raised in red-coloured tank followed by white-, black- and blue-coloured tanks, respectively. Modulation of the main digestive enzymes was observed across four treatments indicating different strategies for the utilization of nutrients by fish. Fish from red- and white-coloured tanks showed a lower level of cortisol and higher levels of heat shock protein (HSP70) when compared to the other groups. The present findings indicate that red colour is the most suitable background colour for rearing Asian sea bass juveniles followed by white colour compared with the other ones.

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.

Full vs. Empty

Full vs. Empty

Effect of stocking density and tank colour on nursery growth performance, cannibalism and survival of the Asian seabass Lates calcarifer (Bloch, 1790) in a recirculating aquaculture system

Cannibalism is one of the major issues causing mortality in the Asian seabass Lates calcarifer nursery phase. The present study aimed to investigate the effects of stocking density and background colour of rearing tanks on the growth performance, cannibalism and the survival of the Asian seabass fry in a recirculating aquaculture system (RAS). The Asian seabass fry was reared in white and black tanks at three stocking densities of 0.5, 1.0 and 1.5 individuals/L for 45 days. The initial body weight of the Asian seabass fry was 0.25 ± 0.00 g, and the total body length was 2.50 ± 0.00 cm. The weight gain, specific growth rate and fish survival were negatively correlated with stocking density, whereas overall yield was higher in higher stocking density. White colour tanks achieved better growth performance (weight gain, specific growth rate, yield, mortality and survival) than black tanks achieved except for cannibalism. There were significant interaction effects between stocking density and tank colour on weight gain, specific growth rate, feed conversion ratio, yield, the type-1 cannibalism, mortality and survival. The study concludes that the Asian seabass fry reared at a stocking density of 0.5 individual/L grows better than the stocking density of 1.0 and 1.5 individuals/L in the RAS and black tanks should be avoided for nursery rearing.

The effect of two carotenoid sources, background colour and light spectrum on the body pigmentation of the clownfishAmphiprion ocellaris

Two studies were conducted in laboratory (E1 and E2) with clownfish juveniles Amphiprion ocellaris in which the survival, growth, body colour and total carotenoid content in the skin were evaluated. In E1, diets supplemented with one of three levels of lutein or astaxanthin (0.5%, 1% and 1.5%) were evaluated; and, subsequently, in E2, two background colours were used in the fish tanks (black/white), which included two different light spectrums (white/red). The survival and growth rate of the fish in both studies were similar irrespective of the treatment. The fish fed the diets supplemented with 0.5% and 1% astaxanthin (E1) exhibited an intense red pigment and a significantly superior (p < 0.05) total carotenoid concentration in skin compared to the other treatments. In E2, an intense red pigmentation and well-defined black bands were observed in fish kept in black background tanks, whereas fish kept in tanks with white background had a yellowish hue and barely visible bands. In contrast, the light spectra did not have an effect on body pigmentation. Based on the results, it was concluded that the body colour of the clownfish depends on the carotenoid source in the diet and the colour of the culture system rather than the light spectra. It is, therefore, recommended that a minimum of 0.5% astaxanthin is included in the diet and that the fish are kept in tanks with a black background, to maintain the intense red coloration that is characteristic of the species.

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.

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.