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1.
The effects of different aeration rates at night to prevent sinking syndrome‐related death (SSRD) of the tiger grouper, Epinephelus fuscoguttatus were examined. The aeration rates were fixed at 300 mL min?1 at daytime (07:00–19:00 hours) and regulated to 0, 300 and 900 mL min?1 at night (19:00–07:00 hours). Larval survival, growth, feeding intake, sinking velocity, distribution and behaviour, stress level, surface tension‐related death (STRD) and flow velocity distribution were assessed. The occurrence of SSRD in the tiger grouper was observed through the accelerated sinking velocity (Vl) (from 0.15 ± 0.09 cm s?1 at 4 days AH to 0.41 ± 0.09 cm s?1 at 12 days AH) coupled with larval passive swimming behaviour at night‐time. On the final day of experiment (15 days AH), larvae reared in 900 mL min?1 at night had attained significantly higher (P < 0.05) survival (34.4 ± 5.5%), growth (5.8 ± 0.5 mm) and feeding intake (60.46 ± 6.98 ind. larva?1). A favourable flow field for the tiger grouper was produced in 900 mL min?1 at night‐time, in which larvae were transported 15–25 cm above the tank bottom and 1.0 cm beneath the water surface. Under these night‐time rearing conditions, larval stress level and number of STRD reared in 900 mL min?1 compared with those observed in 300 mL min?1 remained insignificant, indicating that strong turbulence of flow velocity was not detrimental for larvae. Our findings recommend aeration at 900 mL min?1 at night as this could improve larval survival by reducing SSRD.  相似文献   

2.
Success of swim bladder inflation (SBI) is crucial for early survival of Pacific bluefin tuna (PBF) larvae, because it reduces larval sinking death by enhancing buoyancy. In Experiment 1, we examined the effect of photoperiod on SBI and survival in PBF larvae by comparing photoperiods of 9L: 15D (9L), 14L: 10D (14L: natural photoperiod), 19L: 5D (19L) and 24L: 0D (24L) during 2–10 days post hatch (dph). In Experiment 2, the combined effects of photoperiod (24L and 14L) and nighttime aeration rate (enhanced night‐time aeration: ENA of 1300 mL min?1 as a countermeasure for sinking death and 130 mL min?1) on the survival and SBI were also examined during 2–10 dph. Moreover, in Experiment 3 the effect of photoperiod on vertical distribution of larvae in night‐time was examined on 3–5 dph. Photoperiod of 24L in Experiment 1 significantly inhibited SBI compared with 14L and 19L; nevertheless, it significantly improved survival compared with other photoperiods with a dark period. On the other hand, the shortened light period (9L) showed significantly reduced SBI and also survival. In Experiment 2, the countermeasure for sinking death of ENA under 24L did not further improve the survival; rather it tended to reduce the survival. In Experiment 3, larvae distributed less in the bottom layer in 24L than in 14L, suggesting the reducing effect of 24L on sinking death. The results indicate that 24L without ENA is suitable for survival which is the most serious problem in PBF larviculture.  相似文献   

3.
Early‐stage mortality due to surface water tension‐related death and due to sinking to the tank bottom was investigated for yellowfin tuna, Thunnus albacares (YFT), larvae. Different aeration rates and rearing water surface conditions were examined to evaluate the effect on larval survival, swim bladder inflation and growth. The percentage survival of yolk sac larvae was significantly higher when the rearing water surface was covered with fish oil at aeration rates of 0 and 50 mL min?1. The highest mortality occurred at the highest aeration rate of 250 mL min?1 regardless of surface water condition. A second experiment was conducted twice under different water surface conditions: the water surface was covered by fish oil (FO), skimmed of fish oil (SS), and was not treated (NC). The percentage survival was not significantly different between treatments after 7 days of feeding. In contrast to the survival, the proportion of larvae with inflated swim bladders was significantly higher for the NC and SS groups than that of the FO group. Results of these experiments indicate that the addition of oil to the rearing water surface without its removal interferes with the initial swim bladder inflation in YFT larvae. These results also indicate that YFT larvae need to obtain (gulp) air at the water surface for initial swim bladder inflation, and success of initial swim bladder inflation may be crucial for their survival.  相似文献   

4.
First feeding success is critical to larval marine finfish and optimization of live feed densities is important for larval performance and the economics of commercial hatchery production. This study investigated various rotifer feeding regimes on the prey consumption, growth and survival of yellowtail kingfish Seriola lalandi larvae over the first 12 days post hatch (dph). The common practice of maintaining high densities of rotifers (10–30 ind. mL?1) in the rearing tank was compared to a low density feeding technique, where 5–8 ind. mL?1 of rotifers were offered. A ‘hybrid’ feeding regime offered rotifers at the high density treatment until 5 dph and the lower feeding densities thereafter. There was no significant difference in larval survival (hybrid: 28.9 ± 7%, low density: 17.3 ± 5% and high density: 17.2 ± 9%) or growth (hybrid: 6.12 ± 0.18 mm, low density: 6.03 ± 0.10 mm and high density: 6.11 ± 0.23 mm) between treatments. Rotifer ingestion was independent of rotifer density throughout the trial and increased with larval age, with larvae at 4 dph ingesting 22 ± 1.5 rotifers larvae?1 h?1 and by 11 dph ingesting 59 ± 1.6 rotifers larvae?1 h?1. These data demonstrate that from first feeding, yellowtail kingfish larvae are efficient at capturing prey at the densities presented here and consequently significant savings in rotifer production costs as well as other potential benefits such as facilitation of early weaning and improved rotifer nutritional value may be obtained by utilizing lower density rotifer feeding regimes.  相似文献   

5.
By introducing recirculation aquaculture systems (RAS) in the nursery phase of the blue mussel (Mytilus edulis) (17–18 mm), we aimed at a similar growth and survival and a similar water quality compared to the commonly used flow‐through systems (FTS). To calculate water flow and size of the biofilter, a series of experiments were done to determine clearance rate (9.26 mL min?1), pseudo faeces threshold (60 000 cells Pavlova lutheri mL?1), nitrogen production (0.00065 mg TAN h?1 ind?1 and 1.6 × 10?5 mg NO2–N h?1 ind?1) and oxygen consumption (0.03 ± 0.01 mg O2 h?1 ind?1). RAS showed no significant differences in water quality (0.06 mg TAN L?1; 7.7 mg O2 L?1) and growth performance of mussel seed specific growth rate (SGR = 5% day?1) after the experimental period of 4 weeks compared with FTS. The low water refreshment, 10% per day, as well as the constant chlorophyll concentrations (9.76 ± 1.06 μg L?1), suggests the potential of RAS as culture system for mussel seed.  相似文献   

6.
Knowledge on apparent digestibility coefficients (ADC) is necessary to maximize the feed efficiency, thus lessening dietary nutrient and energy losses. This study tasks the determination of apparent digestibility of selected feedstuff to striped surubim Pseudoplatystoma reticulatum, a carnivorous, South American catfish of economic importance for fisheries and fish culture alike. Juvenile striped surubim (82.4 ± 17.7 g and 23.0 ± 1.6 cm) was distributed in 21 cylindrical, plastic cages (80 L), housed in seven 1000 L feeding tanks under constant water flow and aeration and conditioned to a two daily meals (20h00m and 22h00m) feeding regimen on a practical, reference diet (RD) (460.0 g kg?1 crude protein (CP); 19.23 kJ g?1 gross energy (GE)]. Test diets were obtained by adding of 1 g kg?1 chromium III oxide and 300 g kg?1 of one the following feedstuffs: fish meal (FM), meat and bone meal (MBM), poultry by‐product meal, feather meal, blood meal, soybean meal, wheat bran, corn and corn gluten meal to the RD. After the last daily meal, fish were transferred to cylindrical, conical‐bottomed aquaria (200 L) under aeration and continuous water exchange, coupled to refrigerated plastic bottles for faeces collection by sedimentation. Best ADC of protein (99.36%) and energy (86.25%) were recorded for poultry by‐product meal and MBM, respectively, which are thus deemed ideal surrogate feedstuffs to FM in the formulation and processing of diets for striped surubim.  相似文献   

7.
Garlic, Allium sativum L., extract administered as a therapeutic bath was shown to have antiparasitic properties towards Neobenedenia sp. (MacCallum) (Platyhelminthes: Monogenea) infecting farmed barramundi, Lates calcarifer (Bloch). The effect of garlic extract (active component allicin) immersion on Neobenedenia sp. egg development, hatching success, oncomiracidia (larvae) longevity, infection success and juvenile Neobenedenia survival was examined and compared with freshwater and formalin immersion. Garlic extract was found to significantly impede hatching success (5% ± 5%) and oncomiracidia longevity (<2 h) at allicin concentrations of 15.2 μL L?1, while eggs in the seawater control had >95% hatching success and mean oncomiracidia longevity of 37 ± 3 h. At much lower allicin concentrations (0.76 and 1.52 μL L?1), garlic extract also significantly reduced Neobenedenia infection success of L. calcarifer to 25% ± 4% and 11% ± 4%, respectively, compared with 55% ± 7% in the seawater control. Juvenile Neobenedenia attached to host fish proved to be highly resistant to allicin with 96% surviving 1‐h immersion in 10 mL L?1 (15.2 μL L?1 allicin) of garlic extract. Allicin‐containing garlic extracts show potential for development as a therapy to manage monogenean infections in intensive aquaculture with the greatest impact at the egg and larval stages.  相似文献   

8.
During April to June 2009, a large bolus of Amazon River water impacted the northeastern Caribbean Sea. Shipboard observations collected near Saba Bank, the U.S. and British Virgin Islands, and the Anegada Passage showed low surface salinity (35.76 ± 0.05 Practical Salinity Unit (PSU)), elevated surface temperature (26.77 ± 0.14°C), high chlorophyll‐a (1.26 ± 0.21 mg m?3) and high dissolved oxygen (4.90 ± 0.06 mL L?1) in a 20‐ to 30‐m thick surface layer in the riverine plume. The water was ~1°C warmer, 1 PSU fresher, 0.3 mL L?1 higher in oxygen and 1.2 mg m?3 higher in chlorophyll‐a than Atlantic Ocean waters to the north, with Caribbean surface waters showing intermediate values. Plankton net tows obtained in the upper 100 m of the water column revealed larval fish assemblages within the plume that were significantly different from those of the surrounding waters and from those encountered in the area in previous years. The plume waters contained higher concentrations of mesopelagic fish larvae from the families Myctophidae and Nomeidae, which as adults typically inhabit offshore, deep water habitats. Concentrations of larvae from inshore and reef‐associated families such as Scaridae, Serranidae, Labridae and Clupeidae were lower than those found outside the plume in similar shallow areas, particularly in near‐surface waters. An event like the one observed in 2009 had not been documented in at least the past 30 yr, and yet it was followed by another similarly extreme event in 2010. The ecological implications, including any long‐term consequences of such recent extreme events, are important and merit further study.  相似文献   

9.
A 12‐week feeding trial was conducted in eighteen 70 L indoor polyvinyl circular troughs provided with a water flow‐through system (1–1.5 L min?1) at 28 ± 1 °C to evaluate the dietary tryptophan requirement of fingerling Catla catla (3.45 ± 0.24 cm; 0.60 ± 0.13 g). Six casein‐gelatin‐based amino acid test diets (330 g kg?1 crude protein; 13.6 kJ g?1 digestible energy) containing graded levels of L‐tryptophan (1.0, 1.4, 1.9, 2.3, 2.8, 3.4 g kg?1 dry diet) were fed to triplicate groups of fish near to satiation at 08:00, 12:30 and 17:30 h. Absolute weight gain, feed conversion ratio, protein gain, RNA/DNA ratio, hepatosomatic index, viscerosomatic index, condition factor and haematological indices improved with the increasing levels of tryptophan from 1.0 to 2.3 g kg?1 of dry diet. Significantly higher carcass protein was obtained at 2.3 g tryptophan per kilogram of the dry diet. Exponential analysis of absolute weight gain, feed conversion ratio, protein gain and RNA/DNA ratio against dietary tryptophan levels at 95% maximum and minimum responses displayed the tryptophan requirement at 2.5, 2.3, 2.5 and 2.1 g kg?1 dry diet, respectively. Inclusion of dietary tryptophan in the range of 2.1–2.5 g kg?1 dry diet, equivalent to 6.4–7.6 g kg?1 dietary protein, is recommended in formulating tryptophan‐balanced feed for the culture of this fish species.  相似文献   

10.
Growth response of fingerling Heteropneustes fossilis (6.8 ± 0.2 g; 11.2 ± 0.3 cm) to dietary l ‐leucine levels was assessed by conducting 8‐week feeding trial in a flow‐through system (1–1.5 L min?1) at 28 °C water temperature. Casein–gelatin‐based isonitrogenous (380 g kg?1; crude protein) and isoenergetic [17.9 MJ kg?1; gross energy (GE)] basal diet was supplemented with different levels of l ‐leucine to achieve desired leucine levels ranging between 10 and 22.5 g kg?1 dry diet. Analysed values were 9.9 (Lc9.9), 12.4 (Lc12.4), 15.1 (Lc15.1), 17.4 (Lc17.4), 20.1 (Lc20.1) and 22.4 (Lc22.4) g leucine kg?1 diet. Fishes were stocked randomly in quadruplicates and fed to satiation at 07:00 and 17:30 h. Maximum absolute weight gain (AWG g fish?1), feed conversion ratio (FCR), protein utilization efficiency (PUE%), leucine retention efficiency (LRE%) and haematological parameters were found in fish fed diet Lc17.4. For precise determination of dietary leucine requirement of Singhi, AWG g fish?1, FCR, PUE% and LRE% were subjected to broken‐line and second‐degree polynomial regression analysis. Second‐degree polynomial regression analysis fitted the data more accurately (P > 0.05) exhibiting high R2 values. Hence, based on this analysis, dietary leucine requirement of fingerling H. fossilis is recommended to be 16.5 g kg?1 of the diet, corresponding to 43.4 g kg?1 protein for developing leucine‐balanced commercial feeds.  相似文献   

11.
Particle size distribution, organic content and the sinking velocity of bio‐deposits of abalone Haliotis discus hannai Ino were evaluated. The abalone was divided into three size classes according to shell length: Group B: 68.8 ± 2.8 mm, group M: 56.1 ± 2.3 mm and group S: 42.4 ± 2.8 mm. The faecal pellets had an amorphous shape, with a cross‐sectional area ranging from 0.01 to 2.64 mm2. The mean cross‐sectional area varied among the size classes: 0.59 (B), 0.21 (M) and 0.12 (S) mm2. The bio‐deposit organic content was similar among the groups (B: 18.3 ± 1.1%; M: 19.9 ± 0.9%; S: 19.3 ± 1.0%). Sinking velocity ranged from 0.5 to 2.3 cm s?1. Larger abalone tended to have larger and thus faster‐sinking faecal pellets. The median sinking velocity for groups B, M and S was 0.9, 0.5 and 0.7 cm s?1 respectively. The mean daily production rates for groups S, M and B were 2.8 ± 1.2, 3.4 ± 1.3 and 4.3 ± 1.8 g ind.?1 respectively. Bio‐deposit production rate estimated to be between 134.4 and 206.4 mg m?2 day?1 in the bay. Our results suggest that the pellet size was within the appropriate size range for filter‐feeding bivalves.  相似文献   

12.
Effectiveness and efficiency of frozen sperm on fertilization and hatching success of eggs from silver barb was examined in relation to cryoprotectants, freezing rate and storage period. Sperm was diluted in calcium‐free Hank's balanced salt solution, equilibrated with dimethylsulphoxide (DMSO), propylene glycol, sucrose or methanol at 5%, 10%, 15% or 20% final concentrations, and frozen in 250‐μL straws using a one‐step freezing procedure (1, 5 and 8°C min?1 from 25 to ?40°C). Highest post‐thaw sperm motility was found from a treatment using 10% DMSO and 5°C min?1 (82.2 ± 2.1%), similar to that of 10% DMSO and 8°C min?1 (87.8 ± 3.2%). Post‐thaw motility of sperm frozen at 5 or 8°C min?1 was significantly higher than 1°C min?1. Relative sperm motility declined significantly after 10 months of cryostorage while viability did not change during a 12‐month cryostorage. Average fertilization rates of sperm after 1 and 4 months of storage were 64.5 ± 4.6% and 61.3 ± 3.4%, respectively, similar to those of fresh sperm (69.6–72.3%). Hatching rates of cryopreserved sperm (45.4–51.2%) were similar to those of fresh sperm (51.8–57.8%). This study developed suitable methods for cryopreservation of silver barb sperm that can be used to facilitate hatchery operation.  相似文献   

13.
Effect of various dietary protein levels on growth and nutrient utilization were studied in fringe‐lipped carp, Labeo fimbriatus fingerlings for 60 days. Five practical diets containing graded protein levels of 200, 250, 300, 350 and 400 g kg?1 with respective digestible protein (DP) contents of 192.4, 244.5, 291.6, 339.4 and 391.4 g kg?1 were evaluated as five treatments, T1, T2, T3, T4 and T5, respectively, in triplicate. Each experimental tank (80‐L) contained eight fingerlings (4.9 ± 0.1 g) and was subjected to continuous aeration and 25% water replenishment daily. The fish were fed two times daily at 8:00 and 14:00 h to satiation. Significantly higher (P < 0.05) absolute growth and thermal growth coefficient, and lower feed conversion ratios (FCR) were observed in T2–T4 than T1 and T5. Protein efficiency ratio (PER) and protein productive values (PPV) were highest in T2 and lowest in T5. Significantly higher (P < 0.05) apparent protein digestibility was perceptible in T2–T4. While specific amylase activity declined linearly with increasing DP : DE, the protease, trypsin, aspartate aminotransferase and alanine aminotransferase established polynomial relationship. Based on live weight gain, PER and PPV fitted to quadratic model optimum DP levels were estimated as 301.4, 260.0 and 273.0 g kg?1, respectively.  相似文献   

14.
Under controlled conditions of food density and temperature, larval performances (ingestion, growth, survival and settlement success) of the flat oyster, Ostrea edulis, were investigated using a flow‐through rearing system. In the first experiment, oyster larvae were reared at five different phytoplankton densities (70, 500, 1500, 2500 and 3500 μm3 μL?1: ≈1, 8, 25, 42 and 58 cells μL?1 equivalent TCg), and in the second, larvae were grown at four different temperatures (15, 20, 25 and 30°C). Overall, larvae survived a wide range of food density and temperature, with high survival recorded at the end of the experiments. Microalgae concentration and temperature both impacted significantly larval development and settlement success. A mixed diet of Chaetoceros neogracile and Tisochrysis lutea (1:1 cell volume) maintained throughout the whole larval life at a concentration of 1500 μm3 μL?1 allowed the best larval development of O. edulis at 25°C with high survival (98%), good growth (16 μm day?1) and high settlement success (68%). In addition, optimum larval development (survival ≥97%; growth ≥17 μm day?1) and settlement (≥78%) were achieved at 25 and 30°C, at microalgae concentrations of 1500 μm3 μL?1. In contrast, temperature of 20°C led to lower development (≤10 μm day?1) and weaker settlement (≤27%), whereas at 15°C, no settlement occurred. The design experiments allowed the estimation of the maximum surface‐area‐specific ingestion rate  = 120 ± 4 μm3 day?1 μm?2, the half saturation coefficient {XK} = 537 ± 142 μm3 μL?1 and the Arrhenius temperature TA = 8355 K. This contribution put a tangible basis for a future O. edulis Dynamic Energy Budget (DEB) larval growth model.  相似文献   

15.
Physiological (reference) value intervals determined by the lower 2.5% and upper 97.5% quantiles were calculated for blood plasma cholesterol (CHOL) and triacylglycerol (TGL) in farmed rainbow trout, Oncorhynchus mykiss, in raceway culture. The fish were given dry pelleted diets that contained 37–47% crude protein and 7–14% crude fat and were kept at a stocking density of 50 kg m?3 in tanks provided with running freshwater at an ambient temperature of 3–16°C and dissolved oxygen, 8.4–11.5 mg L?1. Blood was sampled between September and November at a photoperiod of 9:00–13:00 hours: 11:00–15:00 hours (light:dark). Cholesterol levels were significantly (P = 0.0001) greater in males (4.7–12.1 mmol L?1, n = 34, mean weight 406 ± 138 g) than immature females (3.2–9.7 mmol L?1, n = 386, mean weight 416 ± 147 g). Physiological range for TGL in immature females and males was 2.4–14.4 mmol L?1 (n = 249, mean weight 418 ± 149 g). The distribution and density of the quantiles in the tested reference group were made possible by the use of histograms, which showed normal distributions for CHOL in males and in females, but not for TGL, in which a sinistral asymmetry was found. Correlation and regression analyses indicated significant (P = 0.0000) dependence between the CHOL and total protein (r2 = 76.2%), CHOL and Fulton's condition factor (r2 = 43.3%) and CHOL and absolute weight of liver (r2 = 45.5%). Fluctuation in cholesterolaemia and triacylglycerolaemia, depending on nutrition and the aquaculture method is discussed below.  相似文献   

16.
This study focused on methods to reduce bacterial loads in the larval culture tanks of California yellowtail (Seriola lalandi). We conducted two trials to evaluate methods to minimize bacterial loads in the larval rearing water. The first trial examined the use of bentonite clay as a turbidity agent to replace algae in a green water‐type environment. This trial consisted of three treatments: (1) clay with continuous feeding (CCO), (2) clay with batch feedings (CBA) and (3) algae paste with batch feedings (ALG). The results showed that both clay treatments had significantly fewer Vibrio colonies in the water column (CBA – 180 ± 78; CCO – 377 ± 120 CFU mL?1) than the ALG treatment (5692 ± 2396 CFU mL?1) after 14 days of culture. Survival was significantly higher in the CCO treatment (14.1 ± 2.6%) than either the CBA (2.3 ± 0.5%) or ALG treatments (2.8 ± 1.5%). The second trial attempted to limit bacterial loading in the larval culture tank by passively transferring the larvae into an adjacent, clean tank at 1, 5 and 9 days post hatch during the first 2 weeks of culture. The results from this trial showed that after 12 days of culture, water in the transfertank had fewer Vibrio colonies (1025 ± 541 CFU mL?1) than the water in the control tanks (1962 ± 1415 CFU mL?1). Also, survival was significantly higher among larvae that were transferred (43.9 ± 13.5%) than in the control tanks (23.1 ± 6.3%).  相似文献   

17.
The aim of this study was to investigate the effects of different levels of Origanum onites L. essential oil as feed additives on the growth performance, antioxidant activity and disease resistance of rainbow trout. Fish (26.05 ± 0.15 g) were fed the experimental diets supplemented with four different concentrations (0.125, 1.5, 2.5 and 3.0 mL kg?1) of O. onites essential oil for 90 days. Fish fed diets containing essential oil of O. onites had significantly higher final weight than the control group. Feed conversion ratio in fish fed diets containing 1.5 and 3.0 mL kg?1 essential oil of O. onites was improved than other treatments (P < 0.05). The lowest feed conversion efficiency ratio was recorded in the 0.125 mL kg?1 group of O. onites. Antioxidant status of fish was assayed for levels of plasma superoxide dismutase (SOD) and plasma catalase (CAT) activity. Lysozyme activity in plasma was significantly higher in fish fed diet containing 3.0 mL kg?1 essential oil of O. onites (P < 0.05). After 8 weeks of feeding, fish were challenged with Lactococcus garvieae and cumulative mortality was recorded over 15 days. Dietary administration of 0.125, 1.5 and 2.5 mL kg?1 O. onites significantly reduced fish mortality (P < 0.05). The 3.0 mL kg?1 diet showed no mortality after challenged with L. garvieae. These results suggested that the essential oil of O. onites could be applied as growth promoter and also improved disease resistance when added to rainbow trout feed.  相似文献   

18.
ABSTRACT

The effect of photoperiod (24L:00D, 12L:12D, and 00L:24D) and temperature (22 ± 1°C and 28 ± 1°C) on performance of Clarias gariepinus larvae was tested. Larvae weighing 3.2 ± 0.24 mg were cultured in aquaria at a stocking density of 20 fish L?1 and fed twice a day on catfish starter diet (40% CP) at 10 % BW day?1. Highest mean weight gain (31.00 mg), SGR (7.56% day?1), and survival (83%) were achieved at photoperiod and temperature combination of 00L:24D and 28 ± 1°C. Percent survival of larvae differed significantly (p < .05) among treatments with optimal survival of (83%) in treatment combination of 28 ± 1°C and 00L:24D, while lowest survival (40%) in treatment combination of 22 ± 1°C and 24L:00D.  相似文献   

19.
This study evaluated the effects of AQUI‐S®20E (10% eugenol) sedation on the survival and behaviour of yellow perch Perca flavescens (Mitchill) and Nile tilapia Oreochromis niloticus L. held in high loading densities. Fish were held in 0–300 mg L?1 AQUI‐S®20E (0–30 mg L?1 eugenol) for up to 10 h in static tanks. At 17°C, yellow perch held in 200 and 300 mg L?1 AQUI‐S®20E were lightly sedated for up to 7 h. Yellow perch at 200 and 300 mg L?1 AQUI‐S®20E also had >95% mean survival 7‐days post exposure using loading densities up to 360 g L?1. Nile tilapia were only sedated for ≤3 h in concentrations up to 300 mg L?1 at 22°C and had >90% mean survival at loading densities ≤480 g L?1. Ammonia in tanks increased significantly as loading density increased, but treatment with AQUI–S®20E did not reduce ammonia accumulation. Results suggest that AQUI–S®20E was effective to sedate yellow perch and Nile tilapia at high loading densities, but sedation varied with loading density and species.  相似文献   

20.
Nutritional efficacy of fairy shrimp (Streptocephalus sirindhornae) nauplii, as a live food, was studied for growth performance and survival rate of giant freshwater prawn (Macrobrachium rosenbergii) postlarvae. A feeding experiment was designed with four different feeds: dry commercial feed, fairy shrimp nauplii, Artemia sp. nauplii and adult Moina macrocopa. Results from the nutritional composition revealed that fairy shrimp nauplii had protein and lipid contents of 54.58 ± 2.8 g kg?1 and 255 ± 2.8 g kg?1, respectively. The highest value for an individual amino acid in fairy shrimp was lysine (140.7 ± 1.6 g kg?1). The essential amino acids content in the whole body of the larval prawns was in the range of 66.7–67.5 g kg?1. Fairy shrimp nauplii had the highest essential amino acid ratio (A/E) of lysine, similarly, in musculature of prawn larvae. Weight gain and specific growth rate of the postlarvae fed with fairy shrimp nauplii were significantly higher than those fed with Artemia nauplii, adult Moina and dry commercial feed. The presented results suggest that S. sirindhornae nauplii can be used as a nutritionally adequate food for freshwater prawn M. rosenbergii postlarvae.  相似文献   

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