Critical Thermal Minima of age‐0 Australian bass,Macquaria novemaculeata,fingerlings: implications for stocking programmes

Abstract Fishes are often stocked outside natural distribution ranges with inadequate information on target streams, particularly thermal regimes. Australian bass, Macquaria novemaculeata (Steindachner), is a catadromous species that is regularly stocked into upland reaches of rivers and impoundments in south‐eastern Australia. Critical Thermal Minima (CTMin) were determined for age‐0 Australian bass fingerlings with a mean fork length of 64.4 ± 0.4 mm and weighing 3.8 ± 0.8 g. Four treatments were used, including three replicate aquaria for each treatment. Fingerlings were acclimated at either 8 or 15 °C at densities of 15 fish in 56‐L glass aquaria. Water temperatures were then decreased at either 1 °C day^?1 or 1 °C h^?1 until loss of equilibrium (LOE), which occurred between 3 and 7 °C. Mean CTMin among treatments was 3.22–4.64 °C and was influenced by acclimation temperature and rate of temperature decline. Fingerlings acclimated at 8 °C subjected to a temperature decline of 1 °C h^?1 experienced highest LOE temperature. Post‐LOE mortality among treatments was highest at 100% in the 8 °C acclimation with a 1 °C day^?1 temperature decline. Mortalities following LOE occurred within 5 days. The results suggest that stocking age‐0 Australian bass is unlikely to be successful in areas where winter temperatures fall below 6 °C.     

Influence of acclimation temperature on the induction of heat-shock protein 70 in the catfish Horabagrus brachysoma (Günther)

Every organism responds to heat stress by synthesizing a group of evolutionarily conserved proteins called the heat-shock proteins (HSPs) that, by acting as molecular chaperones, protect the cell against the aggregation of denatured proteins and play a significant role in adaptation to temperature. The present study aimed to investigate the critical thermal maxima (CTMax) and the expression of HSP70 in different tissues (gill, brain, muscle and liver) of an endemic catfish Horabagrus brachysoma acclimated at either 20 or 30°C for 30?days. To understand the HSP70 response, fish acclimated to the two temperatures were exposed to preset temperatures (26, 30, 34, 36 and 38°C for 20°C acclimated fish and 32, 34, 36, 38 and 40°C for 30°C acclimated fish) for 2?h, followed by 1?h recovery at their respective acclimation temperatures. The HSP70 levels in the gill, brain, muscle and liver tissues were determined by Western blotting of one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. A significant (P?相似文献   

Characteristics of Blood in Common Carp,Cyprinus carpio,Exposed to Low Temperatures

Changes in blood hemoglobin, hematocrit, leucocrit, osmolarity, lactate, glucose and cortisol concentrations were monitored in common carp, Cyprinus carpio, exposed to decreasing temperatures (from 24°C to 4°C). Two experiments [rapid change (acute) and slow change (chronic)] were conducted. In the acute experiment, it took 3 days for the decrease of water temperatures from 24°C to 4°C. In the chronic experiment, it took 33 days for the decrease of water temperatures from 24°C to 4°C. Blood lactate and hemoglobin concentrations, hematocrit, and leucocrit significantly (P < 0.05) decreased in the cold-treated common carp in both experiments. Hemoglobin concentrations did not decrease until the temperature reached 4°C. Plasma glucose and cortisol levels increased in common carp in acute exposure to 4°C. The levels of plasma chloride and osmolarity did not change significantly (P > 0.05) in the cold-treated common carp in both acute and chronic exposure. Data indicate that levels of blood lactate, hematocrit, hemoglobin, and leucocrit were consistently responsive to the stress of low temperatures in common carp.     

Evaluation of Alternative Protein Sources to Replace Fish Meal in Practical Diets for Juvenile Tilapia,Oreochromis spp

Two feeding experiments were conducted to evaluate if methionine is limiting in practical grow‐out diets for tilapia, Oreochromis spp. Four diets containing 32% protein and 5% lipid were designed to compare the use of diets high in dehulled solvent‐extracted soybean meal (DSESM) and expeller pressed soybean meal (EPSM) compared with a diet containing 6% fish meal (FM). Tilapia (4.78 ± 0.07 g, mean ± SD) were randomly stocked into twelve 600‐L flow‐through tanks at 20 fish per tank. After 6 wk, there were no notable trends or statistically significant differences (P > 0.05) in final mean weight, survival rate, and feed conversion ratio (FCR) among the treatments. Because results of this study indicated that DSESM could totally replace FM in practical diets for juvenile tilapia, a second batch of diets were formulated using other protein sources. Typical levels of cottonseed meal (CSM), DSESM, and meat and bone meal (MBM) were used to evaluate whether methionine could be limiting. Two basal diet formulations were tested either without or with methionine supplement (0.06/100 g diet). The first diet contained 15% CSM, 27% DSESM, and 10% MBM and the second diet contained 15% CSM and 37% DSESM. These diets contained 28% protein and 5% lipid. Tilapia (3.90 ± 0.05 g) were randomly stocked into twelve 60‐L glass aquaria of a recirculation system at 18 fish per aquarium for 5 wk and then moved to the 600‐L flow‐through tanks for five more weeks. After 10 wk, there were no statistically significant differences (P > 0.05) in final mean weight, survival rate, and FCR among the four treatments. Results of the present study indicated that DSESM and EPSM could totally replace FM’s inclusion rate in commercial diets for juvenile tilapia. Furthermore, methionine did not appear to be limiting in practical diets using typical levels of CSM, DSESM, and MBM as primary protein sources.     

The effects of temperature on the uptake and metabolism of benzo[a]pyrene in isolated gill cells of the gulf toadfish,Opsanus beta

The effects of acclimation temperature and acute temperature change on the uptake and metabolism of the procarcinogen benzo[a]pyrene (BaP) by gill cells of the gulf toadfish, Opsanus beta, were examined. BaP was rapidly accumulated by isolated gill cells and uptake rates were directly proportional to BaP concentration in the medium (1 to 100 μg/ml). Uptake rates were higher in cells isolated from fish acclimated to 18°C when compared to cells from 28°C acclimated fish at all incubation temperatures. When cells were exposed to BaP at the respective acclimation temperatures of the fish, uptake rates were similar (0.14 ± 0.01 at 18°C and 0.12 ± 0.01 μg BaP/s/10 mg cells at 28°C). This finding is discussed in view of results which showed a partial compensation of membrane fluidity in plasma membranes isolated from fish from the two acclimation temperatures. At higher incubation temperatures, cells from fish acclimated to 18°C metabolized BaP at a greater rate than those at 28°C (49.6 ± 1.92 and 43.0 ± 2.24 μg/g/8h, respectively, at 23°C). Low but detectable activities of common biotransformation enzymes (aryl hydrocarbon hydroxylase, glutathione-S-transferase) and cytochrome P-450 content were found, however, no significant differences were evident between cells from fish acclimated to different temperatures. To whom to address correspondence     

Gel Forming Ability of Tropical Tilapia Surimi as Compared with Alaska Pollock and Pacific Whiting Surimi

Abstract

Setting and thermal treatment effects on texture and color of tropical tilapia surimi gels were compared to Alaska pollock and Pacific whiting gels. Heat treatments that most favored intrinsic gelling factors of a fish species exhibited strong gel formation. Whiteness values increased as total thermal inputs increased, which reflect the increasing opacity of the gels. Pollock gels were generally the strongest and whitest. Tilapia gel quality was generally second to pollock gels, however, in heat treatments using setting temperatures ≥ 40 °C, tilapia gels were comparable (60 °C setting) or superior (40 °C setting) to pollock gels. The optimum heat treatment for tilapia surimi appeared to be a 40° C setting for 1 hr followed by a 90 °C cook for 15 min. SDS-PAGE patterns of gels prepared with 60°C setting followed by 90 °C cooking elucidated the various degree of protein degradation depending upon the species in a descending order of whiting, tilapia, and pollock.     

A preliminary study on the protein requirements of Chanos chanos (Forskal) fry in a controlled environment

Milkfish (Chanos chanos) fry with an average weight of 40 mg per fish were stocked in 60-l wooden-glass aquaria filled with 30 l of filtered sea water with a salinity of 32–34 p.p.t. and a temperature of 25–28°C. They were fed diets containing 20, 30, 40, 50 and 60% protein and 2740 kcal of digestible energy per kg at a daily rate of 10% of the biomass for a period of 30 days. Fish which were fed the diet containing 40% protein had the highest weight gain which was significantly higher (P < 0.05) than those of fish receiving the lower dietary levels of protein. Slightly lower weight gains were obtained when fish were fed diets containing 50 and 60% protein. Although feed conversion values were not statistically different (P < 0.05) among all treatments, the value for the 40% protein diet (1.96) was the best. The mean survival rates were low for all treatments but was highest for the 40% protein diet. No significant difference (P < 0.05) was found in the survival rates of fish receiving different treatments. Results show that a dietary level of 40% protein was required by milkfish fry for maximum growth, efficient feed conversion and high survival rate.     

Replacement of Fish Meal with Salicornia Meal in Feeds for Nile Tilapia Oreochromis niloticus

Abstract.— We investigated the use of the halophyte salicornia Sulicornia bigelovii as a replacement for fish meal in feeds containing 35% crude protein for Nile tilapia Oreochromis niloticus . Five isocaloric, isonitrogenous diets were formulated with salicornia meal to replace 0%. 20%. 40%. 60%. and 80% of the fish meal in the feed. Another diet was formulated entirely from salicornia meal. Diets were fed to three replicate groups of tilapia fingerlings (mean initial weight = 0.5 g/fish) for 6 wk in 40-L aquaria supplied with 22 C well water. Tilapia growth did not differ ( P < 0.05) for fish fed diets in which 0%. 20%. or 40% of the fish meal in the diet was replaced with salicornia meal. Weight gain was reduced when fish were fed diets with higher levels of salicornia meal, and growth was slowest for fish fed diets formulated entirely from salicornia meal. Body fat was reduced and body moisture content was increased ( P < 0.05) for fish fed diets in which more than 80% of the fish meal was replaced with salicornia meal. We conclude that salicornia meal can replace up to 40% of the fish meal in O. niloticus feeds without affecting growth or body composition.     

Use of shrimp protein hydrolysate in Nile tilapia (Oreochromis niloticus, L.) feeds

A 45-day feeding trial was carried out to evaluate the use of shrimp protein hydrolysate (SPH) in diets for Oreochromis niloticus, L. SPH was included in isonitrogenous diets replacing fish meal protein by 0, 5, 10, and 20% and offered to Nile tilapia juveniles (1.7 ± 0.4 g) stocked in 40-L glass aquaria. The inclusion of SPH produced no significant differences (P ≥ 0.05) in final weight, survival, weight gain, average daily gain, specific growth rate, feed conversion ratio, protein efficiency ratio, or apparent net protein utilization. The inclusion of SPH Nile tilapia diets significantly affected (P < 0.05) the final fish body composition. Protein and ash contents decreased and fat content increased slightly with the increase in SPH. This study has demonstrated that SPH is a promising protein feedstuff and could account for as much as 6% of Nile tilapia diets with no adverse effects on growth and nutrient utilization.     

Effects of water temperatures and dietary protein levels on growth,body composition and blood biochemistry of juvenile GIFT tilapia (Oreochromis niloticus)

This study was carried out to evaluate the effects of water temperature (WT) and dietary protein levels on growth, body composition and blood biochemistry of GIFT tilapia (Oreochromis niloticus; initial average body weight: 38.75 ± 0.61g, n = 20). The fish were fed with six diets contained graded levels of protein (209.6, 251.0, 302.4, 354.3, 401.9 and 456.8 g/kg) and raised in each of WT (22°C, 28°C and 34°C) for 8 weeks. Results showed that the growth, feed utilization and protein efficiency were significantly increased with the increase of dietary protein level and followed by the latter platform at each WT. The fish raised at 28 and 34°C showed similar growth performance, and their values were significantly higher than the fish raised at 22°C (p < 0.05). The lipid contents in whole body were decreases with the increase of dietary protein level at each WT. However, the whole‐body protein, ash and moisture contents were not affected by dietary protein level or WT (p > 0.05). The values of serum biochemical indices (ALP, ALT, AST and TCHO) were all decreased with the increase of dietary protein. The optimal dietary protein requirement for GIFT tilapia to achieve maximal growth performance is 374.4, 301.7 and 304.9 g protein/kg diet at 22, 28 and 34°C, respectively.     

Effects of Temperature on Performance Characteristics and the Cortisol Stress Response of Surubim Pseudoplatystoma sp.

Three experiments were conducted in flow‐through tanks at 24, 27 and 30 C to evaluate growth, food conversion, morbidity, survival, and the cortisol stress response of surubim Pseudoplatystoma sp. at different temperatures. In Experiment 1, fish (mean initial weight, 33.3 ± 7.2 g) reared at 27 and 30 C for 60 d grew significantly faster than fish reared at 24 C (P < 0.05). Fish at the lowest temperature showed the poorest feed conversion ratio (FCR, 5:1), while fish at 27 and 30 C had FCRs of 2.5:1 and 3.5:1, respectively. Mortality and morbidity rates were inversely proportional to the temperatures tested. In Experiment 2, serum cortisol levels following an acute handling stressor peaked at 30 min after stress, returned to near‐resting levels at 1 h after stress, and completely returned to resting levels at 3 h after stress in fish at all temperatures tested. Peak serum cortisol levels were higher in fish at 30 C (321.1 ± 38.8 ng/mL) than those in fish at 27 and 24 C (143.3 ± 37.4 ng/mL and 104.2 ± 37.2 ng/mL, respectively). In Experiment 3, fish (mean initial weight, 67 ± 8.58 g) reared at 27 C for 137 d grew significantly faster than fish at 30 and 24 C. Virtually, all fish reared in 30 C had some sign of morbidity (skin lesions and fin abrasion) compared to only a small percentage of fish in the other two temperatures. Again, the highest cortisol peak level was measured in fish reared at 30 C (117.6 ± 16.7 ng/mL), as compared to fish at 24 and 27 C (99.2 ± 15.5 ng/mL and 80.2 ± 12.8 ng/mL, respectively). Our findings indicate that the optimum temperature for rearing surubim in tanks is 27 C. At 30 C, these fish may suffer from stress, as suggested by the elevated peak of cortisol and morbidity and mortality rates. The relatively rapid cortisol stress response of surubim suggests that they may be more tolerant to handling stressors than other fish species.     

Growth and Feed Utilization of the Tilapia Hybrid Oreochromis mossambicus×O. niloticus Cultured at Different Salinities under Controlled Laboratory Conditions

Abstract.— Growth and feed utilization of the tilapia hybrid Oreochromis mossainbicus × O. niloticus cultured at different salinities under controlled laboratory conditions were studied for 2 mo. Fish (2.32 g mean initial weight) were grown in 113-L aquaria at salinities of 0.5, 17 and 32 ppt at a density of 20 fish per tank. Mean specific growth, food conversion, and food consumption were determined at each salinity. There was no significant difference ( P > 0.05) in growth among the treatments, although feed conversion and feed consumption were significantly improved (P ≤ 0.05) when fish were grown at 17 and 32 ppt.     

Water parameters affect anaesthesia induced by eugenol in silver catfish,Rhamdia quelen

The present study investigated the effects of water pH (5.0, 7.0 and 9.0), hardness (0, 20 and 120 mg CaCO₃ L^?1) and temperature (15, 23 and 30 °C) on the induction of sedation and anaesthesia, and subsequent recovery, of silver catfish exposed to eugenol. Moreover, the blood gas tensions (PvO₂ and PvCO₂) and blood pH in silver catfish acclimated to these temperatures were investigated after exposure to eugenol. Water pH, hardness, temperature and fish size affect the efficacy of eugenol in silver catfish, particularly at the lower concentrations tested (20 and 30 mg L^?1). Sedation of this species can be induced at concentrations as low as 20 mg L^?1, but for anaesthesia, a concentration of at least 40 mg L^?1 of eugenol must be used to compensate for the influence of fish size and water quality. Blood gas tension and pH were affected by eugenol anaesthesia, but only in fish acclimated to 30 °C.     

Temperature effects on acute copper toxicity to juvenile channel catfish Ictalurus punctatus

An experiment was conducted to evaluate the effect of temperature on the acute toxicity of copper sulfate to juvenile channel catfish (Ictalurus punctatus). Alkalinity and hardness were 30 and 26 mg l⁻¹, respectively. The 7–10-g fingerlings were acclimated in four climate chambers at test temperatures of 21, 23, 25, and 27 °C for 2 weeks. After determining an acutely lethal copper dose, aerated tanks of 7.6 l were placed in each climate chamber in quadruplicate. To each, seven acclimated channel catfish fingerlings were added. The 72-h cumulative mortality from 20 mg l⁻¹ copper sulfate was significantly lower in the 27 °C treatment (25%) compared to the 21, 23, and 25 °C treatments, where cumulative mortality was 79–96%. Total mortality at 72 h was significantly correlated (P<0.05) with decreasing temperatures (r=−0.91). This provides evidence of an inverse relationship between toxicity of copper sulfate and water temperature. Survival time, however, decreased with increasing temperatures.     

Growth and physiological changes in scaled carp and blue tilapia under behavioral stress in mono- and polyculture rearing using a recirculated water system

Growth performance, carcass composition, liver and blood parameters ofscaled carp (C), Cyprinus carpio, and blue tilapia (T),Oreochromis aureus, reared for eight weeks in twomonoculture (100%C and 100%T) and two polyculture (60%C–40%T and40%C-60%T) conditions were investigated. In polyculture 40%C–60%T bothspecies achieved the highest levels of specific growth rate and the lowestlevels of food conversion ratio and carcass lipid content. In addition, theyexhibited the highest values of plasma pO₂ and pH and the lowestvalues of plasma pCO₂, cholesterol and albumin, although thedifferences among treatments were not significant in the case of tilapia.Tilapia showed significantly lower plasma Cl^? levels than underthe other conditions. Carp in monoculture and tilapia in polyculture60%C–40%T had the lowest levels of specific growth rate and significantlyhigher levels of liver lipids and plasma triglycerides than in the other groups.In addition, carp in monoculture exhibited a significantly higher haematocritthan in polyculture. No significant variations among treatments were observedconcerning plasma cortisol, glucose, osmolality, Na⁺, K⁺,HCO₃ ^? andHCO₃ ^?/H₂CO₃ in either species.The combination of scaled carp and blue tilapia, in which blue tilapia were themain species, proved to be the best for both species. It was suggested thatgrowth and physiological changes under mono- and polyculture rearing, in anintensive system, seem to be as a result of a different state of stress relatedto fish behavior.     

Dietary Niacin Requirement of GIFT Tilapia,Oreochromis niloticus,Reared in Freshwater

The aim of our experiment was to determine the dietary niacin requirement of genetically improved farmed tilapia (GIFT) tilapia, Oreochromis niloticus, reared in freshwater. Six semi‐purified diets were formulated to contain graded levels of niacin (6.4 [basal diet], 16.8, 36.8, 68.5, 143.8, and 297.8 mg/kg). Each diet was fed to triplicate groups of 30 fish (initial average weight 87.2 ± 3.3 g) for 12 wk in 5.6‐m³ aquaria (r = 1.5 m, h = 0.8 m). Results showed that the weight gain rate (WGR) of the fish increased linearly with dietary niacin levels increasing, but there were no further benefits above 36.8 mg/kg. The niacin concentrations in fish livers were positively correlated with dietary levels of niacin and plateaued when niacin in diet exceeded 84.6 mg/kg. With increasing dietary niacin level, serum high density lipoprotein cholesterol (HDLC) content significantly increased, while serum triacylglycerol (TG) content significantly decreased (P < 0.05). There were no significant differences in serum glucose (GLU) and total cholesterol (T‐CHO) contents in the separate fish groups (P > 0.05). Broken‐line regression analysis showed that GIFT tilapia (87–376 g) require a minimum of 20.4 mg/kg niacin in the diet for maximal growth, and 84.6 mg/kg for the highest liver niacin accumulation.     

The effects of temperature on respiration of Amur sturgeon,Acipenser schrenckii,at two acclimation temperatures

In order to clarify the respiratory responses strategy of Amur sturgeon Acipenser schrenckii exposed to water temperature changes, respiratory parameters of the fish were studied under two temperature regimes: fish acclimated at 13°C for Group I, temperature was increased to 16°C, 19°C, 22°C and 25°C and then returned stepwise to 22°C, 19°C, 16°C and 13°C; and fish acclimated at 25°C for Group II, the water temperature was reduced in steps to 22°C, 19°C, 16°C and 13°C, subsequently, returned to 16°C, 19°C, 22°C and 25°C. The results showed that the respiratory frequency (f_R), oxygen consumption rate (VO₂) and gill ventilation (V_G) of the fish were directly dependent on the acute temperature in both acclimation groups (p < .05). The initial 25°C VO₂ in Group II was significantly higher than the initial 13°C VO₂ in Group I (p < .05), but was significantly lower than that at 25°C in Group I (p < .05). In Group I, respiratory stroke volume (V_S.R) of fish significantly increased or decreased with the acute temperature increases or decreases, respectively (p < .05); oxygen consumption efficiencies (EO₂) of fish did not significantly show differences when temperature increased to 25°C from 13°C (p > .05), but the EO₂ significantly declined while returning to acclimation temperature (p < .05). In Group II, the V_S.R of the fish did not significantly change with acute temperature fluctuations between 25 and 13°C (p > .05), while the EO₂ increased with acute temperature increases (p < .05). The Q₁₀ values for f_R, VO₂, V_S.R, V_G and EO₂ were 1.53–1.72, 1.92–2.06, 1.07–1.60, 1.78–2.44 and 1.11–1.65 at 13–25°C of temperature interval respectively. Amur sturgeon showed partial metabolic compensation to temperature changes. The study results suggest that the ability of Amur sturgeon to regulate metabolism in response to acute temperature changes makes this species good adaptability in the aquaculture rearing.     

Variable versus constant temperature acclimation regimes: Effects on hemoglobin isomorph profile in goldfish,Carassius auratus

Goldfish,Carassius auratus, were acclimated for 2 to 3.5 weeks to three temperature regimes: [1] temporally-constant (10, 20 and 30°C), [2] diurnally-cycling (20 ± 10°C) and [3] randomly-fluctuating (± 2°C at approximately 2h intervals between extremes of 10 and 30°C). No significant differences in hematocrit were evident. Hemoglobin levels in fish at constant 30°C and under randomly fluctuating temperature were significantly elevated. Of the three hemoglobin isomorphs observed, the two minor components (G₁, G₃) tended to decrease in relative abundance with increase in constant temperature, but increased under varying temperature regimes. The converse was true of the principal hemoglobin, G₂. Extent of isomorph variation was correlated with extent of temperature variability. These observations confirm that temperature variability significantly effects thermoacclimatory response. The functional significance of changes in isomorph abundances during the acclimatory process is considered.     

Effects of Dietary Magnesium on Growth and Tissue Magnesium Content of Blue Tilapia Oreochromis aureus

Juvenile blue tilapia Oreochrornis aureus (mean weight 0.5 ± 0.05 g) were stocked into 38 liter glass aquaria receiving Row-through well water containing 0.1 mg magnesium/L and fed semipurified, casein-based diets containing graded levels of magnesium (0.003, 0.008, 0.023, 0.037, 0.050 and 0.065% magnesium, dry weight). Magnesium supplements were provided as anhydrous magnesium sulfate (MgSO₄). No treatment-related mortalities occurred and no visible magnesium deficiency symptoms were observed in any treatment group during the 18 week experimental period. Magnesium concentrations in scale and bone of tilapia fed diets containing 0.023 to 0.065% magnesium were greater ( P < 0.05) than in fish fed diets containing 0.003 to 0.008%. Scale and bone magnesium concentrations did not differ ( P > 0.05) among fish that received dietary magnesium levels of 0.023% or greater. The magnesium content of muscle was higher ( P < 0.05) in fish fed 0.037 to 0.065% magnesium than in those fed 0.003 to 0.008% magnesium. Muscle magnesium concentrations did not differ ( P > 0.05) among fish that received 0.037% or more dietary magnesium. Adequate weight gain and superior feed efficiency occurred in fish fed 0.05 to 0.065% magnesium. Results indicated that diets for O. aureus should contain at least 0.05% magnesium (500 mg Mg/kg dry diet) for optimum growth and normal tissue mineralization.