Tank Colour Research Articles

Combined effects of rearing density and tank colour on the growth and welfare of juvenile white sea bream Diplodus sargus L. in a recirculating water system

Appropriate rearing conditions for successful farming of white sea bream Diplodus sargus L. have not yet been studied in depth, while one of the major problems is the species increased aggressiveness. Given the known effect of density and background colour on fish growth, welfare and social behaviour, the present study aimed to investigate whether the two factors combined could favour D. sargus performance. Juveniles (17.37±0.06 g) were reared in white, light blue and black tanks under low (7 fish tank−1 or 1.96 kg m−3) and high (28 fish tank−1 or 7.79 kg m−3) density for 87 days. Water quality was not affected by experimental treatments. The best overall performance (growth, food utilization, body protein content, liver fatty acids) was achieved under low density and white or light blue tanks. Increased incidence of social interactions was indicated in fish under high density or when reared in light blue and black tanks. The present results clearly suggested that the use of black tanks should be avoided. On the other hand, stocking D. sargus at a density of up to 7.79 kg m−3 may be feasible because productivity was greater even if growth was slower. In this case, however, the use of white tanks is highly recommended.

Effect of tank colour on Artemia ingestion, growth and survival in cultured early juvenile pot-bellied seahorses ( Hippocampus abdominalis)

The effect of the background (tank) colour on feeding activity, growth and survival of early juvenile seahorses Hippocampus abdominalis was investigated in two experiments. In experiment one, two sets of background colour (Set 1: Clear, white, red, blue, black; Set 2: Clear, white, yellow, orange, green) were used to quantify short-term Artemia ingestion in 42-day-old fish, and 7-day-old fish (Set 1 only). No statistical difference was observed between data. In the second experiment 3-day-old seahorses were cultured over 6 weeks in one of six coloured tanks (clear, white, yellow, red, blue, black) in a temperature and photoperiod controlled recirculation system to determine the effect of the background colour on growth, survival and conditioning to tank colour. At the end of the experiment there were no significant differences between any of the parameters tested. Early juvenile seahorses under the described experimental conditions were able to feed, grow and survive in a similar manner in any of the tank colours tested. Seahorses did not appear to display any conditioning to the tank colour in which they were cultured.

FEEDING INCIDENCE, GROWTH AND SURVIVAL RATE IN THE EARLY STAGE OF THE RED-SPOTTED GROUPER, Epinephelus akaara, IN RELATION TO TANK COLOR

The red-spotted grouper, Epinephelus akaara, is one of marine fish species targeted for mariculture in Japan. The artificial mass seedling production of these species has been largely successful. However, the survival is still unstable. The effect of tank colors on the feeding incidence, feeding proportion, growth and survival rates in the early stage of the red-spotted grouper were examined. The results showed the feeding incidence, feeding proportion, growth, and survival rates at different tank colors were highly significantly different (P<0.001). Post hoc multiple comparisons based on Tukey’s test showed significant differences (P<0.05) regarding feeding incidence between yellow (70.45%) compared to white (55.83%), black (48.42%), green (41.67%), blue (35.17%), and red (32.50%). The highest feeding proportion (number of rotifer in the stomach/larvae) was found at yellow (5.62), followed by white (2.47), black (1.97), green (1.92), blue (1.71), and red (1.28). The specific growth rate showed significant differences (P<0.05) were found at yellow (2.14%) and white (1.84%) compared to black (1.46%), green (1.20%), blue (1.15%), and red (1.13%). The survival rate at yellow color (1.22%) was the highest, followed by white (1.09%), black (0.79%), green (0.57%), blue (0.38%), and red (0.37%). Yellow was suitable as tank wall color for rearing of red-spotted grouper larvae.

Effects of tank colour and prey density on first feeding of the spotted sand bass Paralabrax maculatofasciatus (Steindachner) larvae

Effects of tank colour and prey density on first feeding of the spotted sand bass Paralabrax maculatofasciatus (Steindachner) larvae

Effects of tank color on melanin-concentrating hormone levels in the brain, pituitary gland, and plasma of the barfin flounder as revealed by a newly developed time-resolved fluoroimmunoassay

A pleuronectiform fish, the barfin flounder Verasper moseri, reared in a white tank had a smaller ratio of pigmented area of the skin on non-eyed side, grew faster, and had greater melanin-concentrating hormone (MCH)-immunoreactive cell bodies and MCH gene expression in the brain than in the black tank, indicating that synthesis and release of MCH are higher in fish from a white tank. In the present study, a time-resolved fluoroimmunoassay for MCH was developed. MCH levels were assessed in the brain, pituitary gland, and plasma of barfin flounders reared in a white or black tank. A competitive assay using two antibodies was performed among secondary antibodies in the solid phase, MCH antibodies, samples, and europium-labeled MCH. Displacement curves of serially diluted extracts (brain, pituitary gland, and plasma) of the barfin flounder paralleled that of the MCH standard. MCH levels in the brain and plasma were higher in fish reared in the white tank for 5 months than in the black tank. These results suggest that synthesis and secretion of MCH are enhanced with the white background and that MCH is involved in both somatic growth and the skin pigmentation in the barfin flounder.

Effects of tank colour on larval survival and development of mud crab Scylla serrata (Forskal)

Hatchery culture of mud crabs has not yet achieved commercial viability despite decades of research efforts. Further research is therefore needed to better understand larval culture requirements of the crab. Based on anecdotal observations, an experiment was carried out to test whether the background colour of the culture vessel affected larval culture success. Newly hatched larvae of Scylla serrata were reared in culture vessels of five colours, i.e., black, dark green, maroon, sky blue and white. Larval survival and development were monitored daily until all of them either moulted to the first crab stage or died. The results showed clear effects of background colour on larval survival. A general tendency of higher larval survival in darker-coloured backgrounds was evident. In particular, overall zoeal survival for larvae reared in black vessels was significantly higher than those reared in white ones. Background colour also appeared to affect larval development. Larvae reared in darker backgrounds generally had shorter development times and more synchronized moulting. A significant delay in zoeal development was observed in larvae reared in white vessels. Dark backgrounds possibly facilitated more efficient feeding, reduced settlement of larvae at the bottom of the vessels as well as minimized stress. This result appears to be the first to demonstrate that background colour can significantly affect larval survival and development of a crustacean species.

Tank colour and dietary arachidonic acid affects pigmentation, eicosanoid production and tissue fatty acid profile of larval Atlantic cod ( Gadus morhua)

We determined the effect of dietary arachidonic acid (20:4n − 6, ARA) and tank colour (green or grey) on the performance of larval Atlantic cod from 2–28 days post-hatch (dph) using a two-factor, fully orthogonal design. Performance of larvae was assessed by evaluating growth, whole body fatty acid (total and polar lipid) profile, whole body eicosanoid (prostaglandins (PG) E and F) production and pigmentation. Rotifers were enriched on one of four experimental emulsions containing graduated ARA concentrations, and fed to 6 replicate tanks (3 each of green and grey colour) of larvae. Tank colour had no significant effect on larval growth or survival at 28 dph. Significant differences in growth (length and dry weight) were detected among diets, although no direct correlation was recorded between growth and dietary ARA. The whole body fatty acid profile from the total and polar lipid fractions of larvae was directly influenced by the diet. Diet did not influence pigmentation, but larvae held in green tanks had significantly elevated pigmentation on both their head and body compared to those held in grey tanks. The interaction between diet and tank colour had a significant effect on total PGE concentration, while total PGF was not influenced by diet or tank colour. We propose that larvae adapt to their background tank colour by changes in pigmentation (melanophore) dispersal modulated by an elevation of circulating α-melanocyte stimulating hormone, which in turn influences total PGE production. To our knowledge this is the first study to demonstrate a relationship between pigmentation and eicosanoids in larval fish, although the biochemical pathways and mechanisms remain poorly understood.

The effect of tank colouration on survival, metamorphosis rate, growth and time to metamorphosis freshwater prawn (Macrobrachium rosenbergii) rearing

Seedstock-costs of the freshwater prawn Macrobrachium rosenbergii can represent >50% of the total production costs. The purpose of this study was to evaluate the effect of culture tank colouration on survival, metamorphosis rate, weight and time required to reach the postlarval (PL) stage. Newly hatched prawn larvae were stocked into eighteen 16-L plastic culture tanks at a density of 30 L−1. Tank colours evaluated were red, black, white, blue, green and yellow. Larval prawns were fed brine shrimp (Artemia franciscana) nauplii and a supplemental diet. Data indicated that larval tank colour had no significant impact (P>0.05) on the final PL size or days required to reach PL stage. However, total survival was significantly higher (P 0.05) from the red, green or white treatments, but was significantly higher (P<0.05) than the blue treatment. This could have a significant financial impact on commercial hatchery, and growout production, as most larval tanks currently in use are blue or black.

Movement of juvenile swordtail (Xiphophorus helleri Heckel) through a tank bottom grid depends on combinations of grid and tank colour

Movement of juvenile swordtail (Xiphophorus helleri Heckel) through a tank bottom grid depends on combinations of grid and tank colour

Dietary l-tryptophan and tank colour effects on growth performance of rainbow trout ( Oncorhynchus mykiss) juveniles reared in a recirculating water system

The aim of the present study was to evaluate the possible anti-stressful effect of dietary tryptophan supplementation on growth of juvenile rainbow trout ( Oncorhynchus mykiss) reared in different background colour using recirculating water system. Therefore, rainbow trout (4.7 g ± 0.02) were reared for 11 weeks in black, light blue and white tanks and fed either a commercial diet (CD) or the same diet supplemented with tryptophan (2 g 100 g −1 diet). Rearing in black tanks led to reduced final weight and total length, lower food consumption, food conversion ratio and body protein, while no differences were observed between fish reared in light blue or white tanks. Feeding the fish tryptophan supplemented diet resulted in depressed growth, increased food consumption and food conversion ratio, decreased body protein and increased body lipid, reduced liver total lipids and a marked increase in hepatosomatic index (least in fish reared in white tanks). It is concluded that rearing on a black background was stressful for rainbow trout juveniles, while the dietary level of tryptophan used failed as a stress-releasing factor and probably evoked an amino acid imbalance.

Efeito de fatores abióticos na larvicultura de pintado amarelo Pimelodus maculatus (Lacépède, 1803): salinidade e cor de tanque

Abiotic factors determine the success of the larviculture in some fish species. Tank color and the water salinity can cause alterations in the behavior and physiology of the fish post-larvae. The purpose of this experiment was to evaluate the influence of the difference water salinity concentration (0.0&permil;; 0.7&permil;; 1.4&permil;; 2.0&permil;; 2.5&permil; and 5.0&permil;) and the use of white or black tanks in the larviculture of Pimelodus maculatus. The survival rate was affected by water salinity (p&lt;0.05), with the highest rate 45.6&plusmn;3.9%, obtained at a salinity of 2.0&permil; and a total mortality at salinity 5.0&permil;. There was no difference in the survival rate (p&gt;0.05) between post-larvae stocked in black or white tanks with an average value of 31.7&plusmn;17.7%. Therefore, 2.0&permil; proved to be the best salinity for larviculture of the Pimelodus maculatus, and the colors tested did not affect the survival of the post-larvae.

The effect of photoperiod, tank colour and light intensity on growth of larval haddock

In two separate experiments, haddock (Melanogrammus aeglefinus) larvae were raised under different photoperiods (24L : 0D or 15L : 9D), or different combinations of tank colour (black or white) and light intensity (1.1 μmol s−1 m−2 or 18 μmol s−1 m−2). Growth (0.8% day−1 in standard length; 2.9% day−1 in body area) and survival (2%) were not significantly different between photoperiod treatments after 35 days. Larval survival was greater in white versus black tanks after 41 days (2% versus l%, respectively). Growth of larvae was impaired in black tanks at low (1.1 μmol s−1 m−2) light intensity (0.8% day−1 in standard length and 2.2% day−1 in body area versus 1.1% day 21 in standard length and 3.1% day−1 in body area, for all other treatments). Transmission and reflection of light was low in black tanks at low incident light, and there was very little upwelling light. The resultant poor prey to background contrast probably resulted in larvae being unable to consume sufficient food to sustain a level of growth comparable to that in other treatments.

Experiments for the improved use of decapsulated Artemia cysts in intensive culture of African catfish larvae

Feeding dried and vitamin C enriched decapsulated Artemia cysts to African catfish larvae increased their growth rate significantly after 6 days over those fed only freshly decapulated cysts. Groups fed with Artemia nauplii had a significantly higher growth during the experiment, although this difference was not considerably important in practice. Tank colour had no influence on growth. Because of their lower price, the decapsulation of lower quality cysts can be an appropriate feed source in intensive cultures of African catfish larvae.

Growth and Survival of Juvenile Robust RedhorseMoxostoma robustumFed Three Different Commercial Feeds

Abstract The name Moxostoma robustum has been transferred to a recently rediscovered large catostomid, the robust redhorse. The only known population of this species currently exists in the Oconee River in east central Georgia, and efforts are underway to restore it to its historic range. Our study objective was to identify which of three commercial diets, Fry Feed Kyowa C-700 (diet B), Shrimp Production 45/10 (diet SP), or Salmon Starter (diet SS), would provide the best survival and growth of juvenile robust redhorse. Two experiments were conducted, and a completely randomized design was used within each experiment. The two experiments differed in tank color (green; black), length of study (60 d; 30 d), and initial size of fish (27.1 and 44.8 mm total length). Growth was best with diet B; diets B and SP produced the highest survival; and diet SP cost less than the others. We were unable to determine whether the significant differences in growth and survival among fish fed the three diets was a result of...

Effects of light intensity, tank colour and photoperiod on swimbladder inflation success in larval striped bass, Morone saxatilis (Walbaum)

Striped bass, Morone saxatilis (Walbaum), larvae, although physoclistous as adults, initially need to inflate their swimbladders by passing ingested air through a pneumatic duct to the swimbladder. Failure to inflate the swimbladder results in swimbladder atrophy, dysfunctional buoyancy control, deformities, and poor larval survival and growth. The present investigation studied the effects of light intensity, tank colour and photoperiod on the initial swimbladder inflation success of striped bass. In the first experiment, newly hatched larvae were reared for 2 weeks in black or white 350-L circular tanks exposed to incandescent lighting at 163 or 10 lux. Larvae were fed Artemia from 6 days post-hatching (dph). The standard length, and oil globule and yolk areas were measured. Swimbladder condition and evidence of feeding were recorded. To study the effects of photoperiod on inflation, larvae were reared in black tanks exposed to either 8 h:16 h or 16 h:8 h light:dark photoperiods at 139 lux. Striped bass inflated their swimbladders between 6 and 9 dph at 17 oC. Inflation success was significantly higher in black tanks (65%) compared with white tanks (42%), but light intensity did not significantly affect swimbladder inflation. Larval growth and food consumption were better in black tanks, primarily because this treatment resulted in more larvae with inflated swimbladders, although larvae with uninflated swimbladders in black tanks were longer at 12 dph than larvae with inflated swimbladders in white tanks. Larvae that successfully inflated their swimbladders fed earlier and exhibited better growth than larvae with noninflated swimbladders. Larvae reared at higher light intensities used up yolk reserves faster. Exposing striped bass larvae to 8 h:16 h light:dark photoperiods resulted in higher inflation rates (55%) compared to larvae reared at 16 h:8 h light:dark photoperiods (30%). Therefore, black tanks and short photoperiods are preferable for early rearing of striped bass larvae to maximize swimbladder inflation success.

Effects of light intensity, tank colour and photoperiod on swimbladder inflation success in larval striped bass, Morone saxatilis (Walbaum)

Effects of light intensity, tank colour and photoperiod on swimbladder inflation success in larval striped bass, Morone saxatilis (Walbaum)

Expression of MCH and POMC Genes in Rainbow Trout (Oncorhynchus mykiss) during Ontogeny and in Response to Early Physiological Challenges

The expression of the neuropeptide melanin-concentrating hormone (MCH) in two groups of hypothalamic neurones (NLT- and LVR-MCH neurones), and POMC in the pituitary corticotropes and melanotropes, has been examined in rainbow trout larvae using immunocytochemistry and quantitativein situhybridization. The aim was to establish at what stage in ontogeny these cells first respond to two physiological challenges—background color and stress. Trout reared in black or white trays showed adaptive skin pigmentary changes at 10 days posthatching, when fish in a pale environment abruptly exhibited melanin aggregation from a prior dispersed state, although the pigment cells were already competent to respond to adrenalin and MCHin vitroat 3 days. Immunoreactive MCH was detectable in the neurohypophysis at hatching and MCH mRNA in the NLT-MCH neurones (which project to the pituitary) was enhanced at 7 days in the white-reared trout. Immunostainable POMC was also present in the pars intermedia at hatching but their POMC mRNA was unaffected by tank color until 28 days, when it was enhanced in the black-reared trout. It is suggested that early pigment concentration depends on neural signals from the sympathetic nervous system in conjunction with MCH from the NLT rather than on a reduction in αMSH secretion from the pars intermedia. MCH mRNA in the LVR-MCH neurones was increased on a pale environment only 28 days after hatching, suggesting that these cells play little role in the early adaptive pigment response. Previous studies on the ontogeny of cortisol secretion indicate the hypothalamopituitary–interrenal axis can respond to stress by about 14 days. However, the pituitary ACTH cells showed no stress-induced changes in POMC mRNA until 28 days. ACTH release may therefore be dissociated from POMC transcription in the early stages of development. The LVR- and NLT-MCH neurones were both stimulated by stress, LVR-MCH mRNA responding by 14 days and NLT-MCH mRNA by 21 days. Melanotrope POMC mRNA was reduced by stress but the physiological significance of this is not known.

トラフグ稚魚の成長と尾鰭の形状に及ぼす飼育水槽の色，照度および飼育密度の影響

In order to optimumize rearing conditions for seed production of the tiger puffer Takifugu rubripus, the influence of tank color, light intensity, and rearing density on the growth and the normality of caudal fin was examined. Juveniles (36.0mm in total length) were reared under six different conditions for 20 days. Total length, body length, body weight, and the normality of caudal fin reared in a black tank, at low light intensity (1, 000Lx), or at low rearing density (300 individuals per m3) were higher than those of the fish reared in white tank, at high light intensity (4, 000Lx), or at high rearing density (600 individuals per m3), respectively. In addition, the best result was obtained when fish were reared under combined rearing conditions in a black tank, at low light intensity, and at low rearing density.

Larval Rearing and Weaning Techniques for White Bass Morone chrysops

AbstractThe effects of culture parameters of tank color and feeding regimes were examined on larval white bass Morone chrysops during 1994–1995. Under high surface illumination (998 lux), dark tank walls were essential for effective prey capture. Larvae reared in clear glass aquaria did not grow and had died by day 6 of the study. In contrast, 48.7% of the larvae reared in black‐walled tanks were alive on day 24 and had grown to 17.2 mm total length (TL). In another study, larvae were fed rotifers Brachionus plicatilis and Artemia nauplii in different feeding protocols. In one treatment only rotifers (10/mL) were fed day 1 (4 d post‐hatch), rotifers and Artemia (3/mL) were fed days 2–4, and Artemia fed days 5–15. This protocol produced similar growth (mean size 11.7 mm TL) and survival (mean 30.3%) as slower weaning times from rotifers to Artemia. Juveniles (27‐day‐old, 17.2 mm TL) were converted to a dry crumble diet over a 14‐d period by slow transfer from a combination diet consisting of live Artemia nauplii, frozen adult Artemia, plankton flakes and dry crumbles. Survival offish weaned to the dry diet was 64.5%. Most of the mortalities during the weaning period were fish with uninflated swim bladders which were cannibalized by larger fish. Using the above tank culture techniques, white bass were reared to a mean size of 73.2 mm TL (mean weight 5.8 g) over a 73‐d period. This essentially closes the life cycle of white bass.

Effects of tank colour on growth and smoltification of Atlantic salmon ( Salmo salar L.)

Atlantic salmon parr, Salmo salar, were reared in dark green or light grey tanks under a dual photoperiod, consisting of a constant background illumination (LD 24:0) from incandescent bulbs and additional light simulating a natural photoperiod (LDN). Additional light was either yellow light from incandescent bulbs or artificial daylight from fluorescent tubes. There were no significant differences in growth between groups in green or grey tanks, or between groups receiving additional light of different spectral composition. There were strong indications of smoltification in grey tanks, whereas in the green tanks the fish were not considered to be smolts.