Anaesthetic efficacy of clove oil,benzocaine, 2‐phenoxyethanol and tricaine methanesulfonate in juvenile marbled spinefoot (Siganus rivulatus)

Anaesthetics are used in aquaculture and fisheries to facilitate routine procedures, such as capture, handling, transportation, tagging, grading and measurements that can often cause injury or induce physiological stress. Two experiments were performed to assess the efficacies of four anaesthetic agents, clove oil, benzocaine, 2‐phenoxyethanol and MS‐222 on juvenile marbled spinefoot rabbitfish (Siganus rivulatus). In the first experiment we tested the lowest effective doses that produced induction and recovery times in 3 min or less and 5 min or less respectively. Dosages were 70 mg L^?1 for clove oil, 60–70 mg L^?1 for benzocaine, 400 μL L^?1 for 2‐phenoxyethanol and 100–125 mg L^?1 for MS‐222. In the second experiment, we determined optimal concentrations of the four anaesthetics if they were to be used to transport rabbitfish fry. Anaesthetic concentrations suitable for handling and transport were: 10–15 mg L^?1 of MS‐222, 5–10 mg L^?1 of benzocaine, 5 mg L^?1 of clove oil and 50–100 μL L^?1 of 2‐phenoxyethanol. All anaesthetic agents are acceptable for use on S. rivulatus, however, 2‐phenoxyethanol, MS‐222 and clove oil appear to be more suitable than benzocaine. Further studies need to be conducted on effects of high and low doses of anaesthetic agents on physiology of marbled spinefoot.     

Anesthetic Efficacy of Clove Oil,Propofol, 2‐Phenoxyethanol,and Ketamine Hydrochloride on Persian Sturgeon,Acipenser persicus,Juveniles

Anesthetics are commonly used in the aquaculture industry to reduce stress and prevent mortality of fish during transportation, handling, and surgical procedures. This study assessed the efficacy of four anesthetic agents (clove oil, propofol, 2‐phenoxyethanol [2‐PE], and ketamine hydrochloride) on Persian sturgeon, Acipenser persicus, juveniles. In addition, results of the first experiment were used to evaluate sedation concentrations suitable for transportation of Persian sturgeon. The concentrations of anesthetics or sedatives evaluated in the first experiment were: 25, 50, 75, and 100 mg/L for clove oil; 1, 1.25, 2.5, and 5 mg/L for propofol; 110, 330, 550, and 770 mg/L for 2‐PE; and 1250, 2500, 3750, and 5000 mg/L for ketamine hydrochloride. Results show significant reduction in time to anesthesia and significant increase in recovery time with increase in concentration of all anesthetics. The most clinically useful concentrations of anesthetics tested were between 25 and 50 mg/L for clove oil, less than 1 mg/L for propofol, 330 mg/L for 2‐PE, and none of the tested concentrations for ketamine hydrochloride. In the second experiment, juveniles were placed in low concentrations of anesthetic solutions for 24 h and survival assessed. The four anesthetics tested are suitable for light sedation during transportation of A. persicus juveniles. Results are helpful to scientists working with Persian sturgeon aquaculture and restocking programs.     

The use of clove oil, metomidate, tricaine methanesulphonate and 2-phenoxyethanol for inducing anaesthesia and their effect on the cortisol stress response in black sea bass (Centropristis striata L.)

Juvenile and adult black sea bass (Centropristis striata L.) were exposed to various concentrations of four anaesthetics to determine practical dosages for handling as well as for procedures such as bleeding, ovarian biopsy or tag implantation. In experiment 1, juveniles exposed to either 2.0 mg L^?1 metomidate, 15 mg L^?1 clove oil, 70 mg L^?1 tricaine methanesulphonate (TMS) or 200 mg L^?1 2‐phenoxyethanol (2‐PE) reached stage II of anaesthesia in 3–5 min and could be handled for weighing and measuring. All fish had completed recovery to stage III within 6 min. In experiment 2, the established concentrations of each anaesthetic were tested on juveniles to determine their ability to prevent a reflex to a subcutaneous needle puncture. All of the fish exposed to clove oil (20 mg L^?1) and 40% of the TMS‐treated (70 mg L^?1) fish reacted while none of the fish anaesthetized in metomidate (2.0 mg L^?1) or 2‐PE (200 mg L^?1) responded to the needle puncture. In experiment 3, metomidate (5.0 mg L^?1), clove oil (30 mg L^?1) TMS (125 mg L^?1) or 2‐PE (300 mg L^?1) were all effective for performing an ovarian biopsy or tag implantation on adults. In experiment 4, TMS (125 mg L^?1) exacerbated the cortisol response to a short handling stressor during a 30 min exposure. Fish anaesthetized in 2‐PE (300 mg L^?1), metomidate (5.0 mg L^?1) or clove oil (40 mg L^?1) had increased cortisol levels associated with the handling stressor but there were no further increases during the remainder of the experimental period. The results demonstrate that these anaesthetics are effective for sedation and anaesthesia of black sea bass and that the best choice is dependant upon the procedures to be performed.     

Current status of the giant freshwater prawn ( Macrobrachium rosenbergii) industry in China,with special reference to live transportation

The giant freshwater prawn Macrobrachium rosenbergii was first introduced into mainland China by the Chinese Academy of Agricultural Sciences from Japan in 1976. It was cultured at the Guangdong Province Fishery Institute (now as Pearl River Fishery Institute, Chinese Academy of Fishery Sciences). Following these early efforts, giant freshwater prawn culture has gradually spread to northern and inland areas. At this time (2011), China has become the largest producer of giant freshwater prawn in the world. Due to a preference of cooking with fresh aquatic products, Chinese retail markets have developed which have special live‐holding counters. From small rural shops to urban supermarkets and specialty restaurants, live seafoods are commonly available whereby customers pick out the products they wish to purchase and consume. Giant freshwater prawns are produced in over 35 countries throughout the world. They are usually sold either fresh, on‐ice, or frozen. What makes the Chinese prawn industry unique is its focus on a live transportation and marketing model. As a result, numerous innovative live‐transport technologies have been developed which have been key to the success of this expanding domestic industry. In this article, we would like to give a general overview of the giant freshwater prawn industry, its status in China, and the special role live‐transportation has for expanding production of giant freshwater prawns.     

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.     

Effects of water temperature and body weight on anaesthetic efficiency in marbled rabbitfish (Siganus rivulatus)

The effects of four anaesthetic agents, tricaine methanesulphonate (MS‐222) (112.5 mg L^?1), 2‐phenoxyethanol (400 μL L^?1), clove oil (70 mg L^?1) and benzocaine (65 mg L^?1) on juvenile marbled spinefoot (Siganus rivulatus) of three mean body weights (7.3 g, 19.1 g, 55.5 g) and at three temperatures (20, 25, 30°C) were evaluated. In addition, the relationship between body lipid content and efficacy of the four anaesthetic agents was evaluated in juvenile S. rivulatus. Times necessary for induction and recovery were recorded. Significant effects of temperature on induction and recovery times were observed. Induction and recovery times decreased with increasing water temperature. No uniform relationship between body weight of juvenile marbled spinefoot and anaesthetic efficacy was observed. Body fat content was positively correlated with induction time only when MS‐222 was used but did not affect induction times of fish exposed to 2‐phenoxyethanol, clove oil or benzocaine. Recovery times were generally longer for all fish containing more body fat. Results of the study show that anaesthetic efficiency increases with increasing water temperature but is not strongly affected by body weight for juvenile marbled spinefoot. In addition, body fat in fish affected the efficacy of the various anaesthetic agents tested in this study, generally slowing down recovery.     

Comparison of the effects of six stunning/killing procedures on flesh quality of sea bass (Dicentrarchus labrax,Linnaeus 1758) and evaluation of clove oil anaesthesia followed by chilling on ice/water slurry for potential implementation in aquaculture

The effects of different stunning/killing procedures on flesh quality of European sea bass were investigated: (1) anaesthesia with clove oil, (2) anaesthesia with 2‐phenoxyethanol, (3) percussive stunning, (4) immersion in ice/water slurry, (5) chilling on ice and (6) anaesthesia with clove oil followed by immersion in ice/water slurry. Muscle pH values were significantly lower in sea bass anaesthetized or stunned by a blow to the head compared with fish immersed in ice/water slurry, chilled on ice or immersed in ice/water slurry after clove oil anaesthesia. Lightness was highest in sea bass anaesthetized by 2‐phenoxyethanol or percussively stunned and lowest in ice‐chilled fish. Redness and yellowness were highest in fish chilled on ice and lowest in fish anaesthetized with clove oil. Liquid loss, fat loss and shear values were not significantly different among the procedures. In general, lipid oxidation values during refrigerated or frozen storage did not significantly differ among treatment groups. Combination of clove oil anaesthesia followed by chilling on ice/water slurry appears to improve both flesh quality and welfare of sea bass, although the implementation of further studies is warranted to consolidate this finding.     

The ability of clove oil and MS-222 to minimize handling stress in rainbow trout (Oncorhynchus mykiss Walbaum)

The effects of 60‐mg L^?1 clove oil and 60‐mg L^?1 tricaine methanesulphonate (MS‐222) on the blood chemistry of rainbow trout were compared after exposure to handling stress via caudal puncture blood sampling. Fish sampled by caudal puncture and subsequently exposed to anaesthetics showed a typical handling stress response over a 48‐h period. There were no significant differences between the responses of fish exposed to equal concentrations of clove oil and MS‐222, with the following exceptions: the blood glucose at full anaesthesia, and lactate at full recovery increased significantly in the clove oil‐exposed fish. In a subsequent experiment, the stress response observed in fish sampled by caudal puncture and exposed to clove oil and MS‐222 was compared with a non‐anaesthetized control group. The increases in plasma cortisol levels were significantly lower at recovery in fish treated with either anaesthetic compared with the control fish. Fish exposed to MS‐222 had significantly higher cortisol levels at 1 h. These findings show that few differences exist between the anaesthetic effects of clove oil and MS‐222 on the physiological response of fish to stress. However, clove oil is more effective at reducing the short‐term stress response induced by handling and blood sampling, and is recommended as an alternative fish anaesthetic.     

丁香酚的分离及其杀多子小瓜虫活性研究

利用不同极性大小的溶剂石油醚、乙酸乙酯、氯仿、甲醇回流提取丁香制备粗提物,进行杀灭多子小瓜虫幼虫和包囊的药效活性追踪,确定丁香杀虫的活性部位为石油醚提取部分,进而利用硅胶柱层析和中压制备液相等分离技术结合活性追逐试验追踪分离丁香石油醚提取物(对多子小瓜虫幼虫和包囊的100%致死质量浓度分别为50mg/L和80mg/L),最终分离获得一种杀虫活性物质,经质谱、核磁氢谱、核磁碳谱等多种波谱分析技术确定该活性物质为丁香酚。体外杀虫结果表明,丁香酚对多子小瓜虫具有较强的杀灭作用,其对幼虫15min、1h、2h、3h和4h的半数致死质量浓度分别为6.21(5.85~6.65)mg/L、3.50(3.24~3.84)mg/L、2.90(2.62~3.22)mg/L、2.33(2.10~2.50)mg/L和2.15(1.98~2.32)mg/L,对幼虫4h的100%杀灭的质量浓度为3.5mg/L,对包囊6h的100%杀灭质量浓度为3.5mg/L。结果表明,丁香酚是一种具有较好开发前景的杀多子小瓜虫药物。     

Simultaneous effect of sex and dose on efficacy of clove oil,tricaine methanesulfonate, 2‐phenoxyethanol and propofol as anaesthetics in guppies,Poecilia reticulata (Peters)

We studied the simultaneous effect of sex and dose on anaesthesia efficacy to estimate, if possible, the lowest effective dose (LED) for clove oil, tricaine methanesulphonate (MS‐222), 2‐phenoxyethanol (2‐PE) and propofol in mature guppies. LED is the lowest dose needed to reach A5 stage in a mean time of 3 min, with mean recovery (R5) time of 5 min. We used four doses/anaesthetic: 25, 50, 75 and 100 mg/L for clove oil; 120,140,160 and 180 mg/L for MS‐222; 800, 1,000, 1,200 and 1,400 mg/L for 2‐PE, and 7.50, 8.25, 10.00 and 11.25 mg/L for propofol. Each dose was tested on 10 females and 10 males. Morbidity, mortality and behavioural changes were checked on two control groups (10 males and 10 females/group). Sedation (A3), A5 and R5 times were recorded. Significant interactive effect dose*sex on A5 time was found for each anaesthetic agent (p_dose*sex < .05). Except for MS‐222 (p_dose*sex = .284), significant interactive effect dose * sex on R5 time was found (p_dose*sex < .05). A5 time in females tended to be greater than in males, but, in general, R5 times were longer in males. Body size differences between males and females could explain these differences in MS‐222 on A5 time and for clove oil, 2‐PE and propofol on R5 time. No dose simultaneous meet LED′s conditions relating to both A5 and R5 times; therefore the lowest doses inducing A5 in a mean time of 3 min could be a safe guideline for anaesthetic procedure in both male and females.     

Improved survival of rohu, Labeo rohita (Hamilton-Buchanan) and silver carp, Hypophthalmichthys molitrix (Valenciennes) fingerlings using low-dose quinaldine and benzocaine during transport

The effects of fingerlings immersion in low‐dose benzocaine (15 and 30 mg L⁻¹, silver carp and rohu) and quinaldine (100 μL L⁻¹ silver crap and 250 μL L⁻¹ rohu) for 1, 3 and 6 h on stress responses and survival of rohu, Labeo rohita and silver carp, Hypophthalmichthys molitrix fingerlings were evaluated in a transport simulation experiment. Both quinaldine and benzocaine showed low mortalities (0–2%). The total mortality in control (with no anaesthesia) was 30% for rohu and 14% for silver carp. Quinaldine and benzocaine‐treated fingerlings had significantly higher plasma chloride levels than the control in both species. Benzocaine, quinaldine, as well as the control, had an initial elevation of plasma cortisol levels. Benzocaine lost its effectiveness after 3 h exposure while quinaldine persisted throughout the 6 h experimental period. Both sedatives reduced bacterial build‐up compared with the control. No post‐exposure mortality was observed for any of the transport methods assessed 48 h after the treatment. This study suggests that the use of low‐dose benzocaine or quinaldine during transport has positive effect on the survival and health of rohu and silver carp fingerlings.     

Clove oil as an anaesthetic for common octopus (Octopus minor, Sasaki)

We evaluated the anaesthetic effect of clove oil [2‐methoxy‐4‐2‐(2‐propenyl)‐phenol] on the common octopus (Octopus minor), in terms of the time required to become anaesthetized (‘anaesthetic time’) and recovery time. We used a factorial experimental design and administered clove oil at different temperatures (15, 20 and 25°C) and concentrations (50, 100, 150, 200, 250 and 300 mg L⁻¹). We observed a significant (P<0.05) relationship between concentration and temperature, and each variable was effective (P<0.05). Anaesthetic time linearly decreased as the concentration and temperature increased. However, recovery time increased as the concentration increased and temperature decreased. There was no mortality. A concentration of 200 mg L⁻¹ clove oil showed rapid anaesthetic and recovery times in the common octopus, indicating its suitability for this species.     

Efficiency of 2‐phenoxyethanol and Clove Oil for Reducing Handling Stress in Reared Meagre,Argyrosomus regius (Pisces: Sciaenidae)

The effect of two anesthetics, 2‐phenoxyethanol (2‐PE) and clove oil (COil) were studied in meagre, Argyrosomus regius. This study aimed to determine the adequate dose of anesthesia for different aquaculture procedures, to assess a sedative or stressor effect of low anesthetic concentrations, and to assess the effect of low anesthetic doses at high fish densities for longer periods of time on fish survival and behavior. Anesthetics were tested at different concentrations: 2‐PE at 100, 250, 400, 550, and 700 mg/L; COil at 25, 40, 55, 70, and 85 mg/L. Meagre became anesthetized within 10 min when using concentrations above 250 mg/L for 2‐PE and above 40 mg/L for COil. Deep anesthesia was achieved at 700 and 85 mg/L, for 2‐PE and COil, respectively. The fish did not react when blood was collected at these concentrations. Plasma cortisol and glucose levels were similar between sedated meagre with both 2‐PE – 100 mg/L and COil – 10 mg/L, and the control (not sedated; P > 0.05). This suggests that low concentrations of these anesthetics induce similar stress response as handling without anesthesia during routine activities. No mortality was registered when meagre was maintained at high densities with low concentrations of each anesthetic for 2 h.     

Evaluation of freshwater prawn‐small fish culture concurrently with rice in Bangladesh

An integrated aquaculture of freshwater prawn (Macrobrachium rosenbergii) and self‐recruiting small fish mola (Amblypharyngodon mola) was conducted in farmers' rice fields at Mymensingh, Bangladesh. There were four treatments with three replications. Four stocking densities, 10 000, 15 000, 20 000 and 25 000 ha^?1, of freshwater prawn were applied. The stocking density of mola was the same (20 000 ha^?1) in all treatments. During land preparation, triple super phosphate (TSP) and murate of potash (MP) were applied at the rate of 150 and 75 kg ha^?1 respectively. Urea was applied at the rate of 200 kg ha^?1 in equally distributed three installments after 16, 45 and 65 days of rice plantation. Prawns were fed with commercial pelleted feed at 3–8% body weight. All water quality parameters were found to be within the suitable range for freshwater prawn culture. There was a homogenous abundance of plankton communities in all treatments. The results of a 4‐month culture period showed that the average production of prawn ranged from 222 to 388 kg ha^?1, mola 51 to 68 kg ha^?1 and rice 2 880 to 3 710 kg ha^?1. Significantly higher production of both prawn and mola was recorded in the plots where the freshwater prawn stocking density was 15 000 ha^?1. This treatment resulted in a net profit of USD 1100 ha^?1.     

Potential of mixed culture of freshwater prawn (Macrobrachium rosenbergii) and self-recruiting small species mola (Amblypharyngodon mola) in rotational rice–fish/prawn culture systems in Bangladesh

The effects of different stocking densities of freshwater prawn (Macrobrachium rosenbergii) on its growth and production in relation to the presence of small self‐recruiting species mola (Amblypharyngodon mola) were investigated in modified rice fields after rice harvest at Mymensingh, Bangladesh. Keeping the stocking density of mola fixed at 20 000 ha^?1 in each treatment, four densities of freshwater prawn (treatments) were maintained: 10 000, 15 000, 20 000 and 25 000 ha^?1 respectively. The rice plots were limed (CaCO₃) and fertilized with urea, triple super phosphate and cowdung regularly. The prawns were fed daily with commercial pellets. Water quality parameters such as temperature, dissolved oxygen, transparency, pH, total alkalinity, inorganic nitrogen (nitrate, nitrite and total ammonia), chlorophyll a and orthophosphate were determined fortnightly. Numerical analysis of plankton communities was performed monthly. All water quality parameters were found to be within the suitable range for freshwater prawn culture, except high temperature, in the peak summer months. There was a homogenous abundance of plankton communities in all treatments throughout the experimental period. Mola started to breed in the second month of the original stocking with partial harvesting after the second month and continued until the final harvest. The total production of mola ranged between 124 and 152 kg ha^?1 during the 4‐month culture period. The average prawn survival ranged from 49% to 57% without any significant difference among treatments. Freshwater prawn production ranged from 294 to 596 kg ha^?1 with significantly higher production in the treatment where 20 000 ha^?1 freshwater prawn were stocked. This treatment also resulted in a higher net profit margin (74%), indicating that stocking at a combination of 20 000 ha^?1 freshwater prawn and 20 000 ha^?1 mola could be the optimum proposition for prawn–mola culture in modified rain‐fed rice fields after rice cultivation.     

Induction and Recovery from Anesthesia in Channel Catfish Ictalurus punctatus Fingerlings Exposed to Clove Oil

Abstract.— The use of clove oil as an anesthetic for channel catfish Ictalurus punctatus fingerlings was examined. At 100 mg/L. clove oil induced anesthesia within 1 min following exposure. Fish recovered from a 10-min period of anesthesia in 100 mg/L clove oil within 4 min following removal from the anesthetic solution. At clove oil concentrations of 150 mg/L or greater, recovery times were prolonged, requiring longer than 10 min for recovery. At 300 mg/L, mortality was observed with half of the catfish fingerlings failing to recover from the 10-min exposure. Fish could be safely maintained in 100 mg/L clove oil for periods of up to 15 min; exposure for longer than 15 min produced both prolonged recovery times and mortality. At a concentration of 100 ma clove oil produced responses similar to those of the commonly used fish anesthetic MS-222. The low cost of clove oil relative to MS-222 and the extensive testing and use of clove oil in dentistry and as a food ingredient make clove oil an attractive candidate as a fish anesthetic.     

The efficacy of Aqui‐S vet. (iso‐eugenol) and metomidate as anaesthetics in European eel (Anguilla anguilla L.), and their effects on animal welfare and primary and secondary stress responses

The effects of 40 mg/L metomidate and 300 mg/L iso‐eugenol (i.e. 600 mg/L Aqui‐S vet.) anaesthesia on the stress response in European silver eel during a process of complete anaesthesia, recovery and long‐term survival were studied. Metomidate is a hypnotic agent with no analgesia, whereas Aqui‐S vet. is a true anaesthetic. There was no difference between fish exposed to Aqui‐S vet. and metomidate, with respect to time to anaesthesia (mean 3.8 and 2.6 min respectively) and recovery (mean 7.6 and 6.5 min respectively). For the metomidate group, the plasma cortisol concentration increased to a peak during the recovery phase, and was significantly higher than for the Aqui‐S vet. group, which showed no such increase. Fish were kept in tanks with seawater for monitoring of long‐term survival (4 months) after anaesthesia treatment, and no mortality was observed in either group. The results indicate that metomidate is a potential stressor to European eels during exposure, and we do not recommend using metomidate in this species. Aqui‐S vet., however, seems promising as a stress‐reducing anaesthetic for European eel, and if used properly could improve animal welfare and survivability during and after common ecology‐related procedures, as capture, tagging and size measuring.     

Efficacy and toxicity of oxidative disinfectants for the removal of gill amoebae from the gills of amoebic gill disease affected Atlantic salmon (Salmo salar L.) in freshwater

Amoebic gill disease (AGD) of Atlantic salmon is treated commercially by bathing affected fish in freshwater. Recently, the efficacy of freshwater bathing has been questioned, and the aim of this study was to examine the potential for improving bathing efficacy using additives to the freshwater bath. AGD‐affected Atlantic salmon were bathed in 350 L tanks containing oxygenated freshwater to which chlorine dioxide (0–50 mg L^?1), chloramine‐T (0–50 mg L^?1) or hydrogen peroxide (0–100 μL L^?1) was added. Before and following a 3‐h exposure to the freshwater and chemical additive, the gills were removed from a sub‐sample of fish and the number of live amoebae on the gills were counted and smears made for confirmation of the presence of Neoparamoeba pemaquidensis, the causative agent of AGD. Following a further 3‐h exposure, a sub‐sample of fish was bled from the caudal vein and the gills were removed for histological examination. Chlorine dioxide and chloramine‐T at 25–50 and 10–50 mg L^?1, respectively, reduced the number of amoebae on the gills by approximately 50% compared with pre‐exposure numbers. The results from hydrogen peroxide treatment were equivocal and the toxicity of hydrogen peroxide was high. The toxicity of chlorine dioxide varied with freshwater hardness and/or suspended solid load, whereas chloramine‐T toxicity was low, with mortalities attributable only to elevated temperatures at the highest concentration tested. In conclusion, chlorine dioxide and chloramine‐T show promise as potential freshwater additives for the improved removal of N. pemaquidensis and possibly, other amoebae from the gills of commercially farmed Atlantic salmon.     

Comparison of tricaine methanesulphonate (MS222) and clove oil anaesthesia effects on the physiology of juvenile chinook salmon Oncorhynchus tshawytscha (Walbaum)

This study investigated the feasibility of using clove oil as an alternative to tricaine methanesulphonate as a fish anaesthetic, particularly in fish stress research. The physiological stress responses of juvenile chinook salmon Oncorhynchus tshawytscha (Walbaum) anaesthetized with either tricaine (50 mg L^?1) or clove oil (20 p.p.m.) were compared using unanaesthetized fish as controls. Haematocrit, serum cortisol and serum glucose concentrations, serum lysozyme activity and differential leucocyte counts were measured from blood samples collected before, during and upon recovery from anaesthesia and at specified intervals up to 72 h after recovery. Differences between the two anaesthetic groups were not significant for most of the physiological traits measured. Serum lysozyme activity of control fish, however, was significantly suppressed relative to the treated fish for 72 h after stress. Clove oil may be a safe and cost‐effective alternative to tricaine without significantly affecting study results. Furthermore, clove oil may be more practical for field‐based research, because a withdrawal period is unnecessary, and clove oil does not pose an environmental hazard.     

Cortisol and haematological response in sea bream and trout subjected to the anaesthetics clove oil and 2-phenoxyethanol

Clove oil has been tested for anaesthesia induction and recovery time as well as for haematology and stress indicators in the gilthead sea bream and rainbow trout. The former parameters were compared with those generated by 2‐phenoxyethanol. The results showed only slight differences between both anaesthetics in terms of anaesthetic efficiency and physiological effects. In addition, clove oil does not block the cortisol response to stress, as happens with other anaesthetics.