Black Tanks Research Articles

The effect of environmental colour on the growth, metabolism, physiology and skin pigmentation of the carnivorous freshwater catfish Lophiosilurus alexandri.

The growth, physiology and skin pigmentation of pacamã Lophiosilurus alexandri juveniles were evaluated in an experiment using different tank colours (white, yellow, green, blue, brown and black) over an 80 day period. The tank colours did not cause significant differences to final body mass, total length, survival rate, carcass composition (moisture, crude protein, ash, ether extract, calcium, phosphorus, energy), or to plasma protein, triglyceride and cholesterol values. Haematocrit values, however, were highest for fish kept in white tanks (ANOVA P < 0·05), while the greatest haemoglobin levels were recorded for fish kept in blue and brown tanks (P < 0·01). The concentrations of cortisol (P < 0·001) and glucose (P < 0·01) were the most in fish in the black tanks. Tank colour affected skin pigmentation significantly, with fish in white tanks having the highest values of L* (brightness) and the lowest values in blue and black tanks. L*, however, decreased in all treatments throughout the experiment. C*ab increased significantly over the course of the experiment in fish kept in white tanks. Similar increases of C*ab were recorded in the other treatments but to a lesser extent. The use of black tanks during the cultivation of L. alexandri caused stress and should be avoided. Cultivation in white and yellow tanks produced individuals with a pale skin colour, while cultivation in blue and black tanks resulted in juveniles with a darker and more pigmented skin.

Effects of tank colour on growth and survival of taimen Hucho taimen (Pallas, 1773) larvae

This study was conducted to evaluate the effect of tank colour on growth and survival of taimen Hucho taimen larvae. Larvae (initial weight 0.11 ± 0.01 g, 21 days after hatching) were cultured in the water flow-through system. Fifteen aquaria (200 L per aquarium) were randomly allocated into triplicate groups of 500 larvae. The outsides of the tanks were covered in red, blue, yellow, white, or black sheeting. Larvae were fed eight times a day by hand to apparent satiation. The experiment was conducted for 56 days. The results showed that the specific growth rate was significantly affected by tank colour, which was higher in the yellow tank than that of the tank (black or red) (P 0.05). The highest feed intake was observed in fish reared in the yellow tank, followed by that of the white, blue, or black tank, and the lowest was in fish in the red tank. In conclusion, the light-coloured tank (yellow or white) was optimum for rearing taimen larvae based on the growth performance.

Diagnóstico Participativo de Saneamento Básico na Comunidade Rural do Baixo Rio Araguari no Município de Ferreira Gomes - Amapá, Brasil

This study aimed to carry out participatory survey on sanitation in homes of the rural community of the Lower Rio Araguari, in the municipality of Ferreira Gomes. The collection of field data occurred in the period of July and August 2014 and consisted of interviews with closed questions, based on questionnaire adapted from LENE / MSD - Sanitary Improvement Needs Survey Household, the National Health Foundation - FUNASA, record images and the location of the properties of the respondents (GPS). The study found that the health debt in the rural community is huge and needs a proper environmental solution, since there is no piped and treated water distribution network, there is no collection and treatment of sewage, no rainwater drainage nor solid waste collection. The source of water is made by use of streams and rivers (60.5%), followed by own wells (37.2%) and alternative sources (2.3%). The allocation of sewage is performed by black tanks (70.9%), septic tank (23.3%) and 5.8% for alternative sources. Household sanitation, 33.7% have water tank, 70.93% sink (loft), 15.1% tank washing, 29% kitchen sink, 5.8% use domestic filter, 65.12% Private rudimentary, 34.8% bathroom (with toilet and with or without shower and / or sink (sink for personal hygiene) and no use septic tank. This shows that families of this rural community are directly polluting the soil, the water table and water bodies, in particular the Araguari River in its lower portion. Keywords: basic sanitation; environmental unhealthiness; lower Araguari River.

Effects of background colour on growth indices and stress of young sterlet ( Acipenser ruthenus ) in a closed circulated system

In this study, the physiological response and growth performances of Acipenser ruthenus were investigated after a long-term background colour adaptation (12 weeks). Twelve groups of 10 individuals with initial mean body weight of 183 g were reared in black, dark blue, grey and white tanks (three replicates for each colour). At the end of the experiments, growth (initial body weight, final body weight, weight gain per cent, food efficiency ratio, protein efficiency ratio, specific growth rate), blood (cortisol, glucose, pO2, pCO2, pH, haematocrit, osmolality, triglycerides, cholesterol, total lipids) and liver (hepatosomatic index, total lipids, glycogen) parameters were analyzed. Plasma cortisol in the dark-adapted sterlet (21.95 ± 3.9 ng mL−1) was significantly lower than those in white-adapted fish (39.44 ± 6.5 ng mL−1), whereas there were no significant differences in cortisol levels between the grey-adapted fish (23.05 ± 4.1 ng mL−1) and dark blue-adapted fish (24.2 ± 3.6 ng mL−1). A remarkable increase in mean of body weight (%) was detected in dark-adapted sterlet (45.2 ± 3.2) being 27.67%, 12.1% and 11.8% higher than the white, grey and dark blue-adapted fish respectively. The obtained results verified that different background colours lead to different growth performances and physiological responses of starlet, depending on rearing conditions.

Manipulating Culture Conditions and Feed Quality to Increase the Survival of Larval Marble Goby Oxyeleotris marmorata

AbstractFish stocking density, feed quality, and tank color were evaluated for their effects on survival of larval Marble Goby Oxyeleotris marmorata reared at 5‐g/L salinity for 30 d. Feed quality was examined in terms of proximate composition and fatty acid profile. Fish larvae were given rotifers and brine shrimp Artemia spp. nauplii (R‐A) that were fed condensed cells of the phototrophic bacterium Rhodovulum sulfidophilum (bPB) cultured in palm oil mill effluent (POME); under this feeding regime, fish stocked at a density of 15 larvae/L had significantly higher survival (42.0%) than those stocked at 20 larvae/L (33.5%) or 30 larvae/L (9.9%). At the best stocking density of 15 larvae/L, fish survival and growth were further improved when the larvae received either R‐A that were fed the whole culture broth of unsettled bacteria (cPB; survival = 60.9%) or R‐A that were fed POME (survival = 58.6%). Under similar rearing conditions, larvae reared in gray‐colored tanks showed still further significant improvement in survival (79.0%) relative to larvae that were reared in black tanks (32.5%) or transparent tanks (0.7%). Thus, optimal culture conditions for larval survival (71.4–81.9%) included rearing in gray culture tanks, stocking at 15 larvae/L, and a diet of R‐A that were fed cPB or bPB. Under those optimal conditions, survival during the critical larval period (first 10 d posthatch; 91.4–95.7%) was significantly improved. An approximate 2:2:1 dietary ratio of docosahexaenoic acid : eicosapentaenoic acid : arachidonic acid as compared to a fish tissue ratio of 7:2:1 is recommended to improve the survival and production of Marble Goby larvae.

The combined effects of diet, environment and genetics on pigmentation in the Giant Tiger Prawn, Penaeus monodon

The colour of prawns, particularly the Giant Tiger Prawn Penaeus monodon, is highly desired and fetches premium market prices. Prawn pigmentation is influenced by the interaction of a range of factors, including the amount of dietary carotenoid, the distribution of hypodermal pigments, and genetics. These aspects have been studied in isolation, but there is limited knowledge on how these components interact to influence prawn pigmentation. This study tracked the colour of prawns that had been fed four different levels of dietary astaxanthin (Axn) over 6weeks, and then transferred to either black or white coloured tanks. The dietary influence on colour was slow and had only developed after 6weeks. Meanwhile the effect of background colour was rapid, within 15min. Results showed that diet and background colour work in combination to affect prawn colour. The poorest colour was recorded in prawns fed without dietary Axn and transferred to white substrates, and this colour was improved by the addition of dietary Axn. Animals fed without dietary Axn and exposed to black substrates showed an intermediate colour, and this was further improved by the addition of dietary Axn. The best colour was recorded in prawns fed 100mg/kg Axn and exposed to black substrates. The abundance of the epithelial pigment protein crustacyanin (CRCN) was not correlated with prawn colour, suggesting that this protein does not regulate the modifications in response to background colour. Finally, the effect of substrate exposure was assessed on farmed prawns, and indicated a small positive effect on colour during harvesting. These data demonstrate that while short term exposure to black substrates can have positive effects on prawn colour, dietary Axn supplementation can both improve pigmentation of animals exposed to black substrates, and prevent the negative effects of exposure to white substrates.

Effects of rearing density and tank colour on juvenile sharpsnout seabream (Diplodus puntazzo) growth performance

Sharpsnout seabream Diplodus puntazzo has been successfully introduced in Mediterranean aquaculture for reasons of species diversification. However, there is limited information related to specific rearing conditions that the species may require for production optimization in land-based aquaculture. The aim of the present study was to investigate the combined effects of rearing density and background colour on growth performance of sharpsnout sea bream D. puntazzo reared in a recirculating water system. Juveniles (4.0 ± 0.03 g) were reared (duplicated groups) under low (D 16 fish tank−1 or 1 kg m−3) and high (3D 48 fish tank−1 or 3 kg m−3) density in white, light blue and black tanks for 88 days. During the first 53 days of rearing, fish under low density presented better growth than fish under high density. However, in the following period (days 53–88) SGR in 3D-reared fish was significantly higher than in D-reared fish, resulting in no mass differences on day 88. Regardless of rearing density effects, black tanks had a negative effect on growth and should be avoided in sharpsnout sea bream rearing. Within the life stage studied, present growth results, along with those of fish groups homogeneity (coefficient of mass variation, frequency distribution of mass), indicate a change in social interactions according to body size. It is suggested that juvenile sharpsnout seabream should be stocked at low density until they reach approximately 16 g. Afterwards, a higher density seems more appropriate for this species while it also ensures a higher productivity.

Light backscattering in turbid freshwater: a laboratory investigation

The relationship between backscattering and inorganic sediment concentration was examined in a controlled laboratory setting. Different concentrations of two sediment sizes (clay/silt and medium sand) of marine clay deposition were added separately in an opaque black tank containing 500 l of distilled water. The experiment used two optical Environmental Characterization Optics-Backscattering sensors to quantify backscattering in m−1 and NTU. Increasing backscatter coefficients (maximum 5.3 m−1) were observed with increasing suspended particulate concentrations up to 272 and 412 mg l−1 for clay/silt and medium sand, respectively. This demonstrates that a greater range of backscattering values can be measured for highly turbid waters than previously measured in situ. Mass-specific backscattering values for clay/silt (0.02 m2 g−1) are on average higher than for medium sand (0.014 m2 g−1). Although the backscattering ratio [b˜bp(λ)] and refractive index calculated are in accordance with the literature, it is worth noting that the difference in particle size does not exclude differences in matter composition, shape, and other physical factors that contribute to b˜bp variation. The results suggest that further investigation of inorganic optical properties affecting particle size as well as matter composition is required in a controlled environment.

Masculinizing Effect of Background Color and Cortisol in a Flatfish with Environmental Sex-Determination

Environmental sex-determination (ESD) is the phenomenon by which environmental factors regulate sex-determination, typically occurring during a critical period of early development. Southern flounder (Paralichthys lethostigma) exhibit temperature-dependent sex-determination that appears to be restricted to the presumed XX female genotype with the extremes of temperature, both high and low, skewing sex ratios toward males. In order to evaluate other environmental factors that may influence sex-determination, we investigated the influence of background color and cortisol on sex-determination in southern flounder. Experiments involving three sets of tanks, each painted a different color, were conducted at different temperatures using southern flounder of mixed XX-XY genotype. The studies involved rearing juvenile southern flounder in either black, gray, or blue tanks and sex-determination was assessed by gonadal histology. In both studies, blue tanks showed significant male-biased sex ratios (95 and 75% male) compared with black and gray tanks. The stress corticosteroid cortisol may mediate sex-determining processes associated with environmental variables. Cortisol from the whole body was measured throughout the second experiment and fishes in blue tanks had higher levels of cortisol during the period of sex-determination. These data suggest that background color can be a cue for ESD, with blue acting as a stressor during the period of sex-determination, and ultimately producing male-skewed populations. In a separate study using XX populations of southern flounder, cortisol was applied at 0, 100, or 300 mg/kg of gelatin-coated feed. Fish were fed intermittently prior to, and just through, the period of sex-determination. Levels of gonadal P450 aromatase (cyp19a1) and forkhead transcription factor L2 (FoxL2) messenger RNA (mRNA) were measured by qRT-PCR as markers for differentiation into females. Müllerian-inhibiting substance mRNA was used as a marker of males' gonadal development. Control fish showed female-biased sex ratios approaching 100%, whereas treatment with 100 mg/kg cortisol produced 28.57% females and treatment with 300 mg/kg cortisol produced only 13.33% females. These results suggest that cortisol is a critical mediator of sex-determination in southern flounder by promoting masculinization. This linkage between the endocrine stress axis and conserved sex-determination pathways may provide a mechanism for adaptive modification of sex ratio in a spatially and temporally variable environment.

Solar Disinfection in a Community-Scale Water Treatment System: An Analysis of Design Parameters for Humanitarian Engineering and System Sustainability

SODIS, solar disinfection of water in plastic bottles, is a well-known water treatment method in communities lacking developed infrastructure. While SODIS is commonly employed by individuals and family units needing clean drinking water in many parts of the world, a community-scale solar disinfection system is presented in this paper as sustainable, humanitarian engineering concept. A community-scale system may be accepted by communities that reject the individual-bottle SODIS method. The triple bottom line of sustainability (society, environment, and economy) may be met by community-scale systems. To test the treatment effectiveness of the system, experiments were conducted to quantify the solar inactivation rate of total coliform bacteria from contaminated source water. Solar disinfection configurations in tanks and bottles were analyzed for the effect of ultraviolet (UV) light index, water temperature, tank color, plastic covering, and duration of sun exposure. A black tank, covered with a clear, plastic drop cloth of 2 MIL (0.0508 mm) thickness provided the highest inactivation rate of total coliforms. A contour plot of UV index versus water temperature provides guidelines for minimum required sun exposure times for disinfection.

The Effects of light intensity on growth and survival of cuttlefish (sepia officinalis) hatchlings and Juveniles

The effects of three light intensities (100, 350 and 1200 lux) on cuttlefish hatchling rearing performance was studied in black tanks. A total of 270 cuttlefish with a mean wet weight (MWW) of 0.089 ± 0.012 g were used in the experiment, which was undertaken during the first 50 days after hatching (hatchling stage plus the transition to the juvenile stage). According to results of the present study, light intensity is an important factor for growth and survival consistency in cuttlefish rearing. All three light intensity groups displayed exponential growth. The effect of days, light intensity and their interaction only displayed differences (P < 0.05) between light groups in terms of mean wet weight. The 100 lux light intensity promoted the best absolute values of total biomass and total mortality. We believe that the higher mortality observed in 1200 lux reared cuttlefish during the first 10 days after hatching (DAH) was due to light intensity and individual adaptation to light conditions. Therefore, the 100 lux light intensity, obtained with daylight spectrum bulbs, is recommended for cuttlefish rearing during the first 50 DAH. This light setup promotes higher growth and survival rates and lower energetic costs, which are key aspects to consider in a cuttlefish hatchery.

Stress Response of Juvenile Beluga, Huso huso, to Light and Tank Colors

Effects of light and tank colors on stress response of juvenile beluga sturgeon, Huso huso, was investigated by the measurement of some sero-haematological parameters and carcass chemical analysis. The analysis was based on the responses of 64 specimens (initial weight 98.83 ± 1.42 g) reared under white, red, green, or blue light, and 48 specimens reared in white, black, or blue tanks, all for 12 weeks. Blue/green light and black tanks produced positive effects on cortisol that can be related to physiological condition and stress.

Effect of tank colour on larval performance of the Amazon River prawnMacrobrachium amazonicum

The aim of this study was to evaluate the effects of hatchery-tank colours (white, yellow, red, blue, green and black) on the performance of larval culture of Macrobrachium amazonicum. The larvae were fed daily with newly hatched Artemia nauplii. The hatchery-tank colours affected the light level inside the tanks, the consumption of Artemia nauplii (AN), larval development, survival, mass gain and productivity of postlarvae (PL). The overall consumption of Artemia nauplii per larva during the larval cycle was 30% and 45% higher in the green and red tanks respectively. The significant variation of AN consumption among tank colours (P = 0.0006) indicates that M. amazonicum larvae are visual predators. Survival was higher in the black, blue and green tanks, reaching more than 75%. However, the highest productivity was obtained in the black tanks (80.1 PL L−1). Lighter coloured tanks and excess luminosity (more than 2 μmol s−1 m2 at tank bottom) appear to be important stress factors for larvae, contributing to reduce survival and productivity. The results indicate that rearing M. amazonicum in black tanks will improve larvae condition, ensure greater productivity of postlarvae and lower Artemia consumption, increasing technological and economic viability.

Effect of storage tank material and maintenance on household water quality

This study investigated water quality of household water storage tanks in Tiquipaya, Bolivia. Tank age has little effect on water quality. Storage tanks cleaned three or more times per year had statistically less Escherichia coli and turbidity than tanks cleaned less frequently (p = 0.10 and p = 0.06, respectively). There was a statistically significant difference between E. coli counts in tanks cleaned three or more times per year compared with storage tanks cleaned less than once per year (p = 0.01). Polyethylene tanks had statistically higher E. coli counts than fiber cement and fiberglass tanks (p = 0.10 and p = 0.17, respectively). Water temperatures reached their highest levels (34°C) in a black polyethylene tank and temperatures of 20 and 23°C in fiberglass and fiber cement tanks, respectively. Statistically significant increases in total coliforms and E. coli associated with an increase in temperature and a loss of chlorine residual were documented as water traveled from the treatment plant, through the distribution system, and into household cisterns and storage tanks (p values ranged from 0.02 to 0.05).

Larviculture of two neotropical species with different distributions in the water column in light- and dark-colored tanks

The influence of tank color on the visual perception of fish larvae and the success of their cultivation depends on the characteristics of each species combined with environmental factors. In this study, we determined the effect of light and dark tank colors on the larviculture of pacamã (Lophiosilurusalexandri), a species with a benthonic habit, and curimatá-pioa (Prochilodus costatus), which swims actively in the water column. Larvae of pacamã and curimatá-pioa were cultivated for 10 days in 5-L tanks, at a density of 15 larvae L-1 and luminosity of 141.7 ± 8.95 lux, and fed Artemia nauplii. Four tank colors were used: green, light blue, brown, and black (with four replications). Survival, biomass and Fulton's condition factor for pacamã larvae were similar in the different colored tanks. However, the larvae in the green tanks showed lower weight than those cultivated in black and brown tanks, as well as shorter total length than that of larvae in the brown-colored tanks. These results are probably due to the association between tank color and benthonic habitat of the pacamã. For the curimatá-pioa, survival and biomass were similar for the different colors. The weight and Fulton's condition factor were higher for the larvae cultivated in green and blue tanks. This result could be associated with the adaptation of curimatá-pioa larvae to active swimming in the water column, searching for prey.

The effects of tank colour, live food enrichment and greenwater on the early onset of jaw malformation in striped trumpeter larvae

A high incidence of jaw malformation has hindered the production of quality striped trumpeter Latris lineata juveniles and has been correlated with walling behaviour in Artemia-fed larvae. In this study, striped trumpeter were reared from first feeding to 29days post-hatching (dph) in different coloured tanks (black or white), culture conditions (clear or greenwater) and fed different diets (enriched or non-enriched rotifers and Artemia), to examine behaviour, retinoid receptor gene expression and jaw malformation. The highest incidence and severity of jaw malformations occurred in clearwater and enriched diet treatments and were significantly more common in white (70±15%, mean±SD) than in black tanks (26±15%). In black tanks, jaw malformation was significantly more common in larvae fed enriched diets (18±14%) than in those fed non-enriched diets (8±8%) and in clearwater (19±14%) versus greenwater (7±6%). At the end of the rotifer feeding phase, larvae were significantly larger in black than white tanks, and longer in greenwater than in clearwater. In the Artemia feeding phase, larval growth was slowest and mortality was highest in non-enriched diet treatments. Larval length and survival were higher in black tanks and in enriched diet treatments, whilst survival was almost twice as high in greenwater (46±18%) than clearwater (26±13%). The average proportion of larvae walling over the duration of the experiment was higher in white than black tanks, and higher in enriched than non-enriched treatments, with lowest walling in greenwater. There was no consistent relationship between feed intake and jaw malformation. However, there was a significant positive correlation between walling and the incidence of jaw malformation at 29dph in larvae fed enriched diets. The expression pattern of three retinoid receptor genes indicated that live feed enrichment and stress could potentially perturb retinoic acid-associated pathways leading to skeletal abnormality. We found that the use of greenwater, black tanks and enriched live feeds is required for good growth, development, survival and final yield of striped trumpeter. The study emphasises the importance of reducing walling in the culture of oceanic larvae and may have direct application in the rearing of other marine fish with similar malformations.

Measures of Anxiety in Zebrafish (Danio rerio): Dissociation of Black/White Preference and Novel Tank Test

The effects of wall color stimuli on diving, and the effects of depth stimuli on scototaxis, were assessed in zebrafish. Three groups of fish were confined to a black, a white, or a transparent tank, and tested for depth preference. Two groups of fish were confined to a deep or a shallow tank, and tested for black-white preference. As predicted, fish preferred the deep half of a split-tank over the shallow half, and preferred the black half of a black/white tank over the white half. Results indicated that the tank wall color significantly affected depth preference, with the transparent tank producing the strongest depth preference and the black tank producing the weakest preference. Tank depth, however, did not significantly affect color preference. Additionally, wall color significantly affected shuttling and immobility, while depth significantly affected shuttling and thigmotaxis. These results are consistent with previous indications that the diving response and scototaxis may reflect dissociable mechanisms of behavior. We conclude that the two tests are complementary rather than interchangeable, and that further research on the motivational systems underlying behavior in each of the two tests is needed.

Characterization of triacetyl-α-melanocyte-stimulating hormone in carp and goldfish

A triacetyl form of α-melanocyte-stimulating hormone (MSH) was found in carp ( Cyprinus carpio) and goldfish ( Carassius auratus), by selective detection of mass profile for cell secretory granules using direct tissue matrix-assisted laser desorption ionization with time-of-flight mass spectrometry (MALDI–TOF MS) analysis during the investigation of fish pituitaries. The structure of triacetyl-α-MSH in carp and goldfish was further analyzed using a collision-induced dissociation with electrospray ionization mass spectrometry, and determined to be N, O-diacetyl Ser as the N-terminal residue and O-acetyl Tyr at position 2. These modifications for α-MSH in carp and goldfish are structurally different from that of medaka hormone, in which [ N, O-diacetyl Ser 1, O-acetyl Ser 3]-α-MSH has been identified. The profiles of four α-MSH variants, des-, mono-, di- and tri-acetyl forms in goldfish and medaka pituitaries were also examined by direct tissue MALDI–TOF MS analysis, and the percentages as a total of α-MSH molecules were compared for fish reared in a white or black tank for 5 days. Among structural variants, diacetyl-α-MSH was the predominant form in goldfish and N-desacetyl-α-MSH in medaka, respectively. In both species, the relative level of the predominant form in the pituitary of white-adapted fish tended to be lower than that of black-adapted fish. In goldfish, no significant difference was observed in the relative content of triacetyl-α-MSH in both backgrounds, whereas the lowest content of triacetyl-α-MSH was found in black-adapted medaka. These preliminary data indicate that it is difficult to elucidate the relations between the physiological roles and acetylated pattern of α-MSH molecule, depending on species.

Effects of colour on growth of &lt;i&gt;Oreochromis niloticus&lt;/i&gt; (linnaeus 1757) fingerlings

Understanding Oreochromis niloticus behaviour and performance in aquaculture is important to optimize the design, management of tanks, and other culture conditions. The objective of this study is to evaluate how different combinations of tank colours affect the feed intake and growth in O. niloticus fingerlings. A feeding trial was conducted for 75 days to determine the effects of tank colours (black, blue, pink, green and white) on growth and nutrient utilization in O. niloticus (10.0 g) fingerling. Result indicatedthat O. niloticus fed and raised in black and green tanks had better growth performance of 26 ± 0.19 g and 25 ± 0.19 g and specific growth rate of 1.71 ± 0.33 g and 1.67 ± 0.33 g than the others. While the least growthperformance were recorded in the white and pink tanks correspondingly (18.0 ± 0.15 g and 17.5 ± 0.15 g). In conclusion, tank colour is an important factor to consider when planning enhancing the performance of O.niloticus in an intensive culture condition.

Effects of colored light and tank color on growth indices and some physiological parameters of juvenile beluga (Huso huso)

International SturgeonResearch Institute, Guilan, IranSummaryThe influence of colored light and tank color was investigatedon growth performance (body weight, growth rate, carcasscomposition, etc.) and physiological status (blood and plasmaparameters) of beluga (Huso huso) juveniles. The study wasconducted using 64 specimens for colored light treatments withinitial weight 98.83 ± 1.42 (mean ± SE) g which were rearedunder white, red, green and blue light and using 80 specimensfor tank color treatments with initial weight 98.50 ±1.24 (mean ± SE) g which were reared in white, red, green,black and blue tanks, all for 12 weeks. Red light had asignificantly negative impact on beluga growth performance(in contrast with blue light) accompanied with reduced livertotal lipids and plasma albumin and elevated plasma cortisol,glucose, cholesterol and triglyceride (in contrast with the othertreatments). No significant effects of tank color were detectedon growth performance. Nevertheless, most of growth param-eters suggested a positive impact of black tank. Althoughplasma glucose levels in white tank were significantly higherthan the other tank colors, no significant effects of tank colorwere detected for the other physiological parameters. There-fore, based on the obtained results, blue light by establishingcomfort in beluga juveniles spelled increased growth perfor-mance and had positive significant effect on physiologicalconditions. Moreover, taking into consideration the consis-tency of all growth parameters among beluga juveniles rearedin black tanks, it is suggested that considerable results inregard to this treatment may be achieved if the rearing periodprolongs.IntroductionThe living fossil status of the lineage and the unusualmorphologic traits of sturgeons make the research on themscientifically valuable (Gardiner, 1984; Bemis et al., 1997).Caspian Sea is the habitat for the four commercial species ofsturgeon (Khodorevskaya et al., 1997) where their populationsare declining due to overfishing for meat and caviar produc-tion, habitat destruction, and environmental pollution (Billardand Lecointre, 2001). The beluga, Huso huso, is an importantcommercial species in the Caspian Sea and a good candidatefor aquaculture because of their fast growth, market price,propagation in captivity and high marketable value of theircaviar. In order to optimize the cultivation of this species,realizing its behavior and performance in culture conditions issubstantial. Among environmental factors that may influencefish performance in culture are colored light and tank color(Barton, 2002). The effects of colored light on disparate aspectsof fish physiology have been investigated such as growth,survival, neuro-hormonal system, reproduction, behavior andstress response (Head and Malison, 2000; Ruchin, 2001, 2004;Volpato and Barreto, 2001; Bayarri et al., 2002; Naor et al.,2003; Boulcott et al., 2005; Marchesan et al., 2005; Karak-atsouli et al., 2007, 2008). Each of the above studies has beenindicated that various light colors have relieved the physio-logical processes in different species. Hence, it is likely that thisspecies-specific quality relates to consistencies of fish visualstructure with its particular natural habitat traits. The effectsof tank color on different aspects of fish physiology have alsobeen investigated including growth performance, survival, skincolor and stress response (Papoutsoglou et al., 2000, 2005;Tamazouzt et al., 2000; Rotllant et al., 2003; Van der Salmet al., 2004; Jentoft et al., 2006; Strand et al., 2007). Thesestudies have indicated that reactions to tank color may varyaccording to fish species and life stage (Papoutsoglou et al.,2005). While light is easily adjusted in intensive indoor fishcultivation and it is possible to have tanks manufactured inany color, determining suitable light and tank color forfarming beluga is important for optimizing its production andcomfort. The present study aimed to investigate whethercolored light and tank color could affect beluga growthperformance and physiological status (blood and plasmaparameters). For this reason, fish were reared separately underwhite, red, green and blue light and in white, red, green, blackand blue tanks.Materials and methods