Serum biochemical characteristics of Beluga, Huso huso (L.), in response to blood sampling after clove powder solution exposure

In order to investigate the effect of anesthesia on serum parameters, Beluga, Huso huso (L.) were blood-sampled immediately without anesthesia (control) or subjected to following anesthesia procedure: 40, 120, and 240 s exposure to 3,000, 700, and 500 mg l⁻¹ clove solution, respectively. Blood samples were collected after these periods, when fish were immobile and reached stage 4 anesthesia. Results showed that cortisol and glucose levels were significantly high in 700 and 500 but not 3,000 mg l⁻¹ group compared to control. Serum lactate levels were significantly high in 500 mg l⁻¹ group compared to control group. Lactate levels were not significantly differed between control, 3,000, and 700 mg l⁻¹ groups. There were no significant differences in serum levels of cholesterol, total protein, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, Na⁺, Cl⁻, K⁺, and Ca²⁺. Results suggest that rapid anesthesia with higher dose is better than slow anesthesia with lower dose for blood sampling in Beluga.     

Effects of triploidy on the Caspian salmon <Emphasis Type="Italic">Salmo trutta caspius</Emphasis> haematology

The aim of this study was a comparison of key haematological features of diploid (2n) and triploid (3n) Caspian salmon (Salmo trutta caspius). Morphometric indices of erythrocytes were determined on blood smears by light microscopy. Triploidy significantly (P < 0.001) increased all morphometric indices measured in the erythrocytes including cell size, cell surface area, and cell volume. The increase in cell size was larger for the major (27%) axis than for the minor (22%) axis, thus making erythrocytes of 3n Caspian salmon more ellipsoidal. The estimated increase in erythrocyte nuclear volume (87%) was bigger than the theoretical expected 50% increase. Haematological indices were measured manually by hemocytometry. Triploids had lower numbers of red blood cells (RBC: 1,120,000 cells/mL in 2n vs. 700,000 cells/mL in 3n; P < 0.001) but they were larger in size (mean erythrocytic volume [MEV]: 363.1 nm³ in 2n vs. 483.3 nm³ in 3n; P < 0.001). The decrease in RBC number was not compensated by the increase in MEV and, thus, triploidy affected the haematocrit (Hct: 38.8% in 2n vs. 33.06% in 3n; P < 0.05). Total blood hemoglobin concentration was lower in triploid fish (Hb: 9.9 g/dL in 2n vs. 8.9 g/dL in 3n; P < 0.05). In contrast, mean erythrocytic hemoglobin (MEH: 95 μg in 2n vs. 133.2 μg in 3n; P < 0.001) was higher for 3n Caspian salmon as a result of their larger erythrocytes, although MEH concentration (MEHC: 0.26 g/dL in 2n vs. 0.27 g/dL in 3n) did not significantly differ (P > 0.05). White blood cell (WBC) counts (lymphocytes and neutrophiles) were measured and WBC/RBC ratios were calculated. There were no significant differences in WBC (15,710 cells/mL in 2n vs. 12,683 cells/mL in 3n; P > 0.05), lymphocytes, and neutrophils as %WBC as well as WBC/RBC ratios between two ploidy levels (P > 0.05). Triploid Caspian salmon showed higher erythrocyte abnormalities such as ‘twisted’, ‘tailed’, and ‘anucleated’ cells as well as high portions of immature RBC in blood smears in comparison with diploids (P < 0.001).     

Efficacy and effects of clove oil and MS‐222 on the immune‐biochemical responses of juvenile rohu Labeo rohita

The present study determined the effective concentrations of clove oil and MS‐222 in juvenile rohu Labeo rohita for quick induction and recovery. The immune‐biochemical responses due to 0, 1 and 24 hr exposure to those anaesthetics were also evaluated. Of four concentrations of the anaesthetics examined, the lowest effective concentration of clove oil and MS‐222 were 50 µl/L and 125 mg/L respectively. Clove oil and MS‐222 significantly increased the myeloperoxidase, total protein and alkaline phosphatase activity at some of the holding durations. However, superoxide anion production (after 0 and 1 hr) and antiprotease activity (after 24 hr) were significantly reduced in fish exposed to clove oil. Serum glucose content was significantly elevated in the MS‐222‐treated group. Furthermore, the clove oil‐treated group showed significantly higher levels of serum Na⁺ and K⁺, while the aspartate and alanine aminotransferase activities were significantly enhanced in the MS‐222 group. The use of both clove oil and MS‐222 is advised as an anaesthetic agent for rohu with a bias towards clove oil, considering its economic and operational feasibility.     

Correlation of hematology and plasma chemistry levels in silver crucian carp Carassius langsdorfii

ABSTRACT: The correlation between hematology and plasma chemistry was examined in natural silver crucian carp Carassius langsdorfii. Three microsatellite DNA markers identified five clonal lines. Blood was obtained from the caudal vessels and analyzed using automatic analysis systems. The correlation between several parameters including erythrocyte count (RBC), mean corpuscular hemoglobin concentration (MCHC), alkaline phosphatase (ALP), plasma glucose (Glu) and total protein (TP) was assessed by liner regression. Hemoglobin (Hgb) and hematocrit (Hct) as a function of the erythrocyte count, hematocrit as a function of the hemoglobin, mean corpuscular hemoglobin (MCH) as a function of the mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC) as a function of the mean corpuscular hemoglobin, and total protein as a function of triglyceride (TG) were positively correlated for the five clonal lines. Different regression slopes ( b -value) of RBC to Hgb and Hct were found among clonal lines, while no such differences were found among slopes of the remaining regression equation. This phenomenon suggests that the significantly different slopes among parameters, which indicated low genetic influence at the each parameter, clearly detected the genetic influences as the compound effect of these parameters.     

Purification and characterization of pepsinogens and pepsins from the stomach of rice field eel (<Emphasis Type="Italic">Monopterus albus</Emphasis> Zuiew)

Three pepsinogens (PG1, PG2, and PG3) were highly purified from the stomach of freshwater fish rice field eel (Monopterus albus Zuiew) by ammonium sulfate fractionation and chromatographies on DEAE-Sephacel, Sephacryl S-200 HR. The molecular masses of the three purified PGs were all estimated as 36 kDa using SDS–PAGE. Two-dimensional gel electrophoresis (2D-PAGE) showed that pI values of the three PGs were 5.1, 4.8, and 4.6, respectively. All the PGs converted into corresponding pepsins quickly at pH 2.0, and their activities could be specifically inhibited by aspartic proteinase inhibitor pepstatin A. Optimum pH and temperature of the enzymes for hydrolyzing hemoglobin were 3.0–3.5 and 40–45°C. The K _m values of them were 1.2 × 10⁻⁴ M, 8.7 × 10⁻⁵ M, and 6.9 × 10⁻⁵ M, respectively. The turnover numbers (k _cat) of them were 23.2, 24.0, and 42.6 s⁻¹. Purified pepsins were effective in the degradation of fish muscular proteins, suggesting their digestive functions physiologically.     

Reproductive dynamics and nursery habitat preferences of two commercially important Indo-Pacific red snappers <Emphasis Type="Italic">Lutjanus erythropterus</Emphasis> and <Emphasis Type="Italic">L. malabaricus</Emphasis>

Red snappers were examined for reproductive biology and age-0 habitat preferences. Spawning in red snappers occurred throughout the year in northern Australia and eastern Indonesia; at least 10–30% of females and 40–80% of males were in ripe or spawning condition in most months. Northern Australian populations showed a spawning peak from July to December (L. erythropterus) and September to March (L. malabaricus). Eastern Indonesian L. malabaricus had a less defined pattern with two peaks: January–March and October. Size at first maturity was 240 mm for males and 250–300 mm for females. L ₅₀ estimates were similar between species in northern Australia: 270–280 mm (males) and 350–370 mm (females). Maximum batch fecundity was 676,100 oocytes for L. erythropterus and 997,000 oocytes for L. malabaricus. Higher mean abundances of age-0 L. erythropterus were found in silty and coarse sand/rubble estuarine habitats of northern Australia (456 ± 119 fish/km²) compared with sandy coastal habitats (5 ± 3 fish/km²). Most age-0 snapper caught at Sape (eastern Indonesia) were L. malabaricus (91%) with mean abundances of 312 ± 14 fish/km². The similarities in the reproductive characteristics of red snappers suggest that successful management approaches adopted in northern Australia should be considered in eastern Indonesia.     

Relationship between concentrations of odorous compounds and biomass of phytoplankton and actinomycetes in freshwater ponds of Beijing,China

The odorous compounds including geosmin and 2-methylisoborneol (MIB) were detected in intensively cultivated freshwater ponds in Beijing, China, by coupling head space solid-phase microextraction with gas chromatography mass spectrometry (GC-MS). Moreover, the biomass of phytoplankton and actinomycetes in the fishponds were determined simultaneously, and the relationship between the concentrations of these odorous compounds and the biomass of phytoplankton and actinomycetes was assessed. The results showed that among the odorous compounds detected, geosmin was the main one, and concentrations of 1.22–35.58 ng l⁻¹ were found in all fishponds. Besides, MIB with 1.39–6.00 ng l⁻¹ was found in parts of fishponds. Six phyla and 22 genera of algae were observed in the fishponds with a biomass of 17.33–178.34 mg l⁻¹, among which dominant phyla were Bacillariophyta and Euglenophyta. Four genera of actinomycetes with a gross biomass of 0–76 × 10⁴ ind l⁻¹ were found in the fishponds, of which Streptomyces spp. was the dominant genera. This indicated that geosmin concentration in fishponds was related with the total biomass of the dominant algae. The results showed that Melosira spp. and Cyclotella spp. were the main microalgae to cause off-flavor in Beijing’s intensively cultivated freshwater ponds in summer and autumn, while Euglenophyta and other algaes played a small role in causing off-flavor.     

Tolerance response to ammonia and nitrite in hatchlings paralarvae of <Emphasis Type="Italic">Octopus vulgaris</Emphasis> and its toxic effects on prey consumption rate and chromatophores activity

Ammonia and nitrite are among the most important water quality parameters. The aim of this study was to determine the acute toxicity of unionized ammonia and nitrite on newly hatched Octopus vulgaris paralarvae. Concretely, survival, feeding and chromatophore activity were examined under different NH₃ and NO₂ ⁻ concentrations. The median lethal concentration (LC 50) determined for 24 h was 10.7 ppm for NH₃ and 19.9 ppm for NO₂ ⁻. Based on these results, a concentration range was chosen to test the effect of this environmental contaminants in feeding and chromatophore activity (range between 2.5 and 20 ppm for feeding and 10 and 30 ppm for chromatophore activity), resulting in modifications in both parameters. In fact, a significant decrease (P < 0.05) in Artemia nauplii consumption by the paralarvae was observed with an increase in NH₃ and NO₂ ⁻. Similarly, the chromatophore activity was also affected by concentration of these contaminants, with decreasing response (P < 0.05) when submitted to stressful situations, as the ammonia and nitrite concentration was increased.     

Red blood cell indices of rainbow trout Oncorhynchus mykiss (Walbaum) in aquaculture

A direct non‐parametric method was used to calculate reference (physiological) haematology values for farmed 10–12‐month rainbow trout of the Kamloops strain (mean weight: 330±131 g) with respect to red blood cell counts (RBCc), haematocrit values (Hct), haemoglobin concentrations (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentrations (MCHC). The fish in the selected reference group (n=798) were given dry pelleted diets that contained 37–47% crude protein, 7–18% crude fat and 108–300‐mg vitamin E, 1.08–5‐mg folic acid, 0.018–0.05‐mg vitamin B₁₂, 48–64.5‐mg iron, 4.5–8.4‐mg copper and 0.18–0.24‐mg selenium supplied per kg of diet. Ethoxyquin and butylhydroxytoluol were used to protect the fat component against oxidation. The fish were kept at a stocking density of 50kg per cubic metre in tanks provided with running freshwater (dissolved oxygen 8.4–11.5 mg L^?1, with O₂ saturation of 77–98%) at an ambient temperature of 0.2–16°C. Blood was sampled between September and November at a photoperiod of 9–13 h:11–15 h (light:dark). Reference ranges for the preceding haematological indices were as follows in immature females (males): RBCc, 0.77–1.42T L^?1 (T – tera, 10¹²) (0.98–1.55T L^?1); Hct, 0.304–0.502 (0.34–0.546); Hb, 54–93 g L^?1 (59–97 g L^?1); MCV, 282–469 fL (279–434 fL); MCH, 51–86 pg (47–78 pg); MCHC, 0.15–0.22 (0.15–0.2). In males, values for RBCc, Hct and Hb were significantly higher (P=0.01 and 0.0000 respectively) and those for MCV, MCH and MCHC were significantly lower (P=0.01 and 0.0002 respectively) than in immature females. Nutritional and environmental factors affecting erythropoiesis in trout and some correlations between haematological (RBCc, Hb, Hct) and biochemical indices of the blood plasma (total protein, cholesterol) are discussed.     

Acute toxicity of ammonia on juvenile cobia (Rachycentron canadum, Linnaeus, 1766) according to the salinity

Juvenile cobia (Rachycentron canadum) (total length 15.16 ± 0.92 cm and weight 19.26 ± 4.5 g) were exposed to different concentrations of ammonia–N (unionized plus ionized ammonia as nitrogen), using the static renewal method at different salinity levels of 5, 20, and 35‰ at pH 8.1 and 25°C. The 24, 48, 72, 96 h LC₅₀ values of ammonia–N for R. canadum juveniles were 60.28, 48.57, 37.42, 22.73 mg l⁻¹ at 35‰; 51.25, 43.63, 28.17, 19.05 mg l⁻¹ at 20‰; and 39.48, 25.31, 19.50, 8.13 mg l⁻¹ at 5‰, respectively. The 24, 48, 72, 96 h LC₅₀ values of NH₃–N (unionized ammonia as nitrogen) were 1.81, 1.46, 1.12, and 0.68 mg l⁻¹ at 35‰; 1.75, 1.49, 0.96, and 0.65 mg l⁻¹ at 20‰; and 1.52, 0.97, 0.71, and 0.31 mg l⁻¹ at 5‰, respectively. As the salinity decreased from 35 to 5‰, susceptibility of ammonia–N increased by 34.5, 47.88, 50.56, and 64.23% after 24, 48, 72, and 96 h exposure, respectively. Furthermore, we found that exposure of fish to ammonia–N caused an increase in oxygen consumption of 129.1, 157.5, and 192% and a decrease in the ammonia excretion level of 53.4, 38.2, and 23.3% with respect to the control.     

Effects of formalin on haematological and blood chemistry in olive flounder, Paralichthys olivaceus (Temminck et Schlegel)

Erythrocytes of olive flounder, Paralichthys olivaceus (Temminck et Schlegel), were treated with serial concentrations of formalin (37% formaldehyde) to investigate in vitro haemolysis and methaemoglobin formation. In addition, the short‐term toxicity of formalin concentrations of 0, 100, 212 and 300 ppm was also studied by clinical tests in which fish were subjected to 3‐h bath exposure. There was no haemolysis of fish erythrocytes exposed to formalin concentrations ranging from 31.3 to 2000 ppm. Methaemoglobin formation, however, was induced at concentrations greater than 500 ppm. Red blood cell count, haemoglobin, haematocrit, mean corpuscular haemoglobin concentration and percentage of immature erythrocytes were also markedly elevated in all formalin‐exposed groups (P<0.05). Formalin exposure also caused significant increases in alkaline phosphatase, aspartate aminotransferase, lactate dehydrogenase, potassium, chloride, magnesium and inorganic phosphorus (P<0.05). However, total protein decreased significantly in the formalin‐exposed groups (P<0.05). No significant differences in white blood cell count, mean corpuscular volume, mean corpuscular haemoglobin, albumin, glucose, total cholesterol, high‐density lipoprotein cholesterol, free cholesterol, alanine aminotransferase, calcium, creatinine and total bilirubin were observed in the formalin‐exposed groups (P>0.05).     

The study of some haematological and serum biochemical parameters of juvenile beluga (<Emphasis Type="Italic">Huso huso</Emphasis>) fed oligofructose

A study was conducted to investigate the effects of dietary oligofructose (1, 2 and 3%) on the blood profiles of beluga (Huso huso) juveniles (18.77 ± 0.76 g) compared to fish fed an un-supplemented diet. After 7 weeks of feeding on the experimental diets, haematological parameters, metabolic products (cholesterol, glucose and total protein) and serum enzymes (lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase) were measured. Compared to the control group (0% oligofructose), dietary oligofructose had no effect on red blood cell counts (RBC), mean corpuscular volume (MCV), mean cellular haemoglobin (MCH) or mean cell haemoglobin concentration (MCHC) (P > 0.05). However, haemoglobin (Hb) concentration, leucocyte (WBC) levels and the proportion of lymphocytes were significantly higher (P > 0.05) in the 2% oligofructose fed fish than in the 3% oligofructose fed fish. Additionally, haematocrit (Hct) values (P = 0.049) and the proportion of lymphocytes (P ≤ 0.01) were significantly higher in the 2% oligofructose group than in the control group. Although serum glucose and total protein remained unaffected, serum cholesterol was significantly lower in the 2% oligofructose group than in the control and 3% oligofructose group (P < 0.05). The results of the present study showed that oligofructose had no significant effects on serum lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase. These results indicate that fish blood profiles could be affected by prebiotics, which should be taken into account in future studies.     

The teleost pseudobranch: a role for preconditioning of ocular blood supply?

The physiological relevance of the teleost pseudobranch as a remnant of a reduced gill arch is still unclear. Numerous hypotheses have been proposed regarding its physiological role, but direct confirmatory evidence is lacking. The close relationship by serial blood flow arrangement with the fish eye’s choroid rete has sparked the idea that pseudobranchial preconditioning of blood pH may facilitate initiation of the Root effect and thus support the establishment of high oxygen tensions for retinal diffusive supply. This idea was critically tested by studies on isolated pseudobranchs in situ (Oncorhynchus mykiss), perfused with RBC/Ringer or RBC/plasma suspensions of widely varied composition (pH 7.4–8.2). Detailed analysis of inflowing as compared to effluent perfusates indicated normal aerobic metabolism expressed by a rise in Pco₂ (+0.39 ± 0.13 mmHg ), an oxygen utilization of 25% and a high oxygen consumption of ∼400 nmol g⁻¹ min⁻¹. Upon passage of the pseudobranch, pH (corrected for Haldane effect) was only slightly acidified (−0.03 to −0.10), [HCO₃ ⁻] and [lactate] were slightly enhanced (+0.51 mmol l⁻¹ or 0.13 mmol l⁻¹, respectively). In order to test for yet unknown plasma components involved in pseudobranch function, a second series of experiments was conducted using RBC-suspensions in fresh plasma instead of Ringer, with results closely resembling those of the RBC/Ringer series. Lacking any physiologically significant correlation with the level of perfusate pH, the obtained data indicate pseudobranchial basic metabolic activity rather than pH regulatory characteristics. Also the observed absolute changes in pH are negligible in terms of pH regulation towards the Root-threshold. Accordingly, the present experiments as well as plausibility evaluation of mechanisms do not support the idea of blood pH pre-adjustment prior to entry into the choroid rete structure of the teleost eye to facilitate the Root-mediated oxygen release.     

Immunostimulating influence of herbal biomedicines on nonspecific immunity in Grouper Epinephelus tauvina juvenile against Vibrio harveyi infection

Herbals such as Cynodon dactylon, Piper longum, Phyllanthus niruri, Tridax procumbens, and Zingiber officinalis were extracted with acetone, benzene, butanol, and petroleum ether and screened against the pathogen Vibrio harveyi isolated from the infected Grouper Epinephalus tauvina. Among the different solvent extractions screening to V. harveyi, petroleum ether extracts were suppressed significantly (P < 0.05). Equal proportions of the all-plant extracts were mixed with the artificial feeds at concentrations of 100, 200, 400, and 800 mg kg⁻¹ of diet and fed to grouper juveniles of 20 ± 2 g average weight for a period of 60 days. Every 20 days, fish juveniles were challenged with V. harveyi and the immune response was studied. The herbal diets significantly (P < 0.05) increased the survival, growth, and immune responses compared to the control group. The herbal diets were significantly improved (P < 0.01) in immune parameters such as phagocytic activity and albumin–globulin (A–G) ratio. Among the different concentrations of the herbals in the diet, the 400 mg kg⁻¹ diet was the most effective in the experiment.     

Experimental nursery culture of the mud crab <Emphasis Type="Italic">Scylla paramamosain</Emphasis> (Estampador) in China

For the improvement of nursery culture of the mud crab Scylla paramamosain, a special nursery facility was purposely designed and built. This facility consists of nursery ponds (areas of 20, 50, and 120 m², respectively) and a seed collecting pond connected to each nursery pond. There were 140 nursery facility units in operation for large-scale juvenile crab production. A series of experiments were carried out using the facility to investigate the effects of the age of megalopae, stocking density, and culture duration of both megalopae and first-stage crabs on the survival of megalopae and early juveniles of S. paramamosain. The results showed that when megalopae were stocked at a density between 3,000 and 5,000 ind m⁻² and reared to reach the first-stage crabs, a survival rate of up to 50% could be achieved. When the first-stage juvenile crabs were stocked at a density between 2,000 and 3,000 ind m⁻², their survival was more than 50% after 14 days of culture.     

Dietary protein requirement for fingerling Channa punctatus (Bloch), based on growth, feed conversion, protein retention and biochemical composition

An 8-week feeding trial was conducted in a flow-through system (1–1.5 L min⁻¹) at 27°C to determine dietary protein requirement for Channa punctatus fingerlings (4.58 ± 0.29 g) by feeding six isocaloric diets (18.39 kJ g⁻¹, gross energy). Diets containing graded levels of protein (300, 350, 400, 450, 500 and 550 g kg⁻¹) were fed to triplicate groups of fish to apparent satiation at 09:00 and 16:00 h. Maximum absolute weight gain (AWG; 8.11 g fish⁻¹), specific growth rate (SGR; 1.82%) and best feed conversion ratio (FCR; 1.48) were recorded in fish fed diet containing 450 g kg⁻¹ protein, whereas protein efficiency ratio (PER; 1.52), protein retention efficiency (PRE; 25%), energy retention efficiency (ERE; 78%) and RNA/DNA ratio (3.01) were maximum for the group fed dietary protein at 400 g kg⁻¹. Second-degree polynomial regression analysis of AWG, SGR and FCR data against varying levels of dietary protein yielded optimum dietary protein requirement of fingerling between 462.24 and 476.72 g kg⁻¹, whereas the regression analysis of PER, PRE, ERE and RNA/DNA ratio data showed a lower protein requirement of 438.28–444.43 g kg⁻¹ of the diet. Considering the PER, PRE, ERE and RNA/DNA ratio as more reliable indicators, this protein requirement is recommended for developing quality protein commercial feeds for C. punctatus fingerlings.     

Effects of temperature and salinity on oxygen consumption and ammonia excretion of juvenile miiuy croaker, <Emphasis Type="Italic">Miichthys miiuy</Emphasis> (Basilewsky)

The metabolic responses of the juvenile Miichthys miiuy in terms of oxygen consumption and ammonia excretion to changes in temperature (6–25°C) and salinity (16–31 ppt) were investigated. At a constant salinity of 26 ppt, the oxygen consumption rate (OCR) of the fish increased with an increase in temperature and ranged between 133.38 and 594.96 μg O₂ h⁻¹ g⁻¹ DW. The effect of temperature on OCR was significant (P < 0.01). Q₁₀ coefficients were 6.80, 1.41, 1.29 and 2.36 at temperatures of 6–10, 10–15, 15–20 and 20–25°C, respectively, suggesting that the juveniles of M. miiuy will be well adapted to the field temperature in the summer, but not in the winter. The ammonium excretion rates (AER) of the fish were also affected significantly by temperature (P < 0.01). The O:N ratio at temperatures of 6, 10, 15 and 20°C ranged from 13.12 to 20.91, which was indicative of a protein-dominated metabolism, whereas the O:N at a temperature of 25°C was 51.37, suggesting that protein-lipids were used as an energy substrate. At a constant temperature of 15°C, the OCRs of the fish ranged between 334.14 (at 31 ppt) and 409.68 (at 16 ppt) μg O₂ h⁻¹ g⁻¹ DW. No significant differences were observed in the OCR and AER of the juveniles between salinities of 26 and 31 ppt (P > 0.05). The OCR and AER at 16 ppt were, however, significantly higher than those at 26 and 31 ppt (P < 0.05), indicating salinity lower than 16 ppt is presumably stressful to M. miiuy juveniles.     

Menthol and 1,8‐cineole as new anaesthetics in common carp,Cyprinus carpio (Linnaeus, 1758)

This study describes anaesthetic efficacy of menthol and 1,8‐cineole in common carp, Cyprinus carpio, in comparison with eugenol. Common carp fingerlings were exposed to eugenol: 5, 10, 15, 25, 35, 50, 75, 100, 150 and 200 ppm; menthol: 5, 10, 15, 25, 50, 100, 200, 300, 400, 500 and 600 ppm; 1,8‐cineole: 100, 150, 200, 300, 400, 500, 600, 700 and 800 ppm. Induction time and recovery time were recorded. Results showed that menthol and 1,8‐cineole anesthetized the fish at higher concentrations compared to eugenol. The fish exposed to menthol showed common fish behavioural responses to anaesthesia, similar to eugenol. But, 1,8‐cineole‐exposed fish showed tail‐up swimming, which was not observed before. Also, 1,8‐cineole failed to completely cease muscle tone. Exposure to 200 ppm eugenol and 600 ppm menthol resulted in 40% and 20% mortality, respectively. Induction time was exponentially dependent on anesthetic concentrations. Recovery time was linearly correlated to eugenol and menthol, but not 1,8‐cineole concentrations. Recovery time was exponentially dependent on induction time in the fish anesthetized with eugenol and menthol, but not 1,8‐cineole. Menthol and 1,8‐cineole are recommended for carp anaesthesia. Menthol is capable to anesthetize common carp within 1–3 min at 118–512 ppm. Common carp anesthetized with 108–133 ppm menthol recovers within 5 min. 1,8‐cineole failed to anesthetize common carp within less than 150 s at 300–800 ppm concentrations. However, it anesthetizes carp within 3 min at 595 ppm concentration. Also, 1,8‐cineole is not recommended for fish surgery. Both menthol and 1,8‐cineole were less efficacious than eugenol.     

Weaning of the wedge sole <Emphasis Type="Italic">Dicologoglossa cuneata</Emphasis> (Moreau): influence of initial size on survival and growth

The weaning phase can be decisive in fish-culture viability. In this work, the relationship between the initial size and weaning success has been studied in wedge sole (Dicologoglossa cuneata). For each age (30, 50, and 70 days after hatching, DAH), two to three sizes were selected, and all were put on the same feeding schedule for 20 days. Each batch (three replicates) was sampled at 1, 10, and 20 days. Specific growth rate (SGR) and survival were compared at the end of the co-feeding period, after 10 days on dry feed only. The best results for survival and growth were found with the smallest larvae, and vice versa. The SGRs and survival rates recorded during the co-feeding period were higher (0.8–15.6 day⁻¹ and 68.3–97.8%) than those from the dry-food phase (0.9–4.7 day⁻¹ and 56.3–66.7%). Successful weaning (survival = 65% and SGR = 9.3 day⁻¹) is possible with 30 DAH larvae (7.6–8.1 mm and 3.9–4.6 mg). In conclusion, the most effective weaning would be possible at 30 DAH, implying significant Artemia savings (25–50%).     

Shrimp shell as a potential sorbent for removal of arsenic from aqueous solution

This study examined the ability of shrimp shell to remove arsenic (As) from aqueous solutions. The shells of two species of shrimp, black tiger shrimp Penaeus monodon and white shrimp Litopenaeus vannamei, were chosen to be the sorbents. Laboratory exposure experiments estimated uptake and depuration rate constants (i.e., k ₁ and k ₂) as well as the bioconcentration factors (BCF) of the shells of the two shrimps. A first-order one-compartment model was presented to describe the uptake kinetics of As in shrimp shell. The resulting k ₁, k ₂, and BCF values of black tiger shrimp were 0.034–1.722 ml/g/day, 0.007–0.345 g/g/day, and 5.08 ± 1.56 ml/g, while those for white shrimp were 0.053–0.523 ml/g/day, 0.011–0.237 g/g/day, and 3.95 ± 1.88 ml/g, respectively. The sorption capacities of black tiger shrimp shell and white shrimp shell were 1.08 × 10⁻⁴–6.66 × 10⁻³ and 1.04 × 10⁻⁴–3.26 × 10⁻³ mmol/g, respectively. The sorption capacity of shrimp shell increased with the initial As concentration in water. Shrimp shell, as a waste material, could be potentially used for the removal of As from an aqueous medium. Although the As-removal capacity of shrimp shell was lower than those of natural and chemical sorbents, using shrimp shells as sorbents is less expensive and could increase the additional value of shrimp products.