KNOWLEDGE SUMMARY

Keywords: ANAESTHESIA; ANALGESIA; FISH; OPIOID; PAIN; PAIN RELIEF; SURGERY

Do opioids provide adequate analgesia for surgical coeliotomy in teleost fish?

Shannen Schultz, BSc(VetBio) DVM^1*

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¹ The University of Adelaide School of Animal and Veterinary Sciences, Adelaide, Australia
* Corresponding author email: shannenj.schultz@gmail.com

Vol 10, Issue 1 (2025)
Submitted 04 Feb 2024; Published: 04 Mar 2025
DOI: https://doi.org/10.18849/ve.v10i1.702

PICO question

For teleost fish undergoing surgical coeliotomy, do intramuscular exogenous opioids reduce perioperative pain, compared with no analgesia?

Clinical bottom line

Category of research

Treatment.

Number and type of study designs reviewed

Four studies were critically reviewed. All were randomised controlled trials, 2 with a parallel group design, and 2 with a factorial crossover group design.

Strength of evidence

Moderate.

Outcomes reported

The studies produced contradicting results regarding the analgesic efficacy of opioids perioperatively, with some evidence of pain alleviation when assessing behavioural parameters, but not when assessing clinical pathology or quantitative cardioventilatory data.

Conclusion

Perioperative use of opioids for teleost fish undergoing invasive surgical procedures may reduce behavioural changes associated with pain compared with no analgesia, but there is insufficient evidence to determine if they provide adequate pain relief based on the study methodologies.

How to apply this evidence in practice

The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.

Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.

Clinical scenario

An ornamental fish keeper and avid aquarist approaches you, a first-opinion practice clinician, because one of their teleost fish has a distended abdomen, and on examination you are suspicious of an abdominal tumour. You plan to perform a coeliotomy under anaesthesia to identify the cause of the abdominal distension and want to construct an analgesic plan to go with it. You have experience with and access to opioid analgesia in your clinic, and you wish to find evidence to inform whether opioids would be an appropriate choice of perioperative analgesia in this case.

The evidence

Four relevant laboratory-based randomised controlled trials, which are high on the hierarchy of evidence, were identified which satisfied the PICO question. All four studies investigated the effect of opioids on teleost fish undergoing surgery under anaesthesia. Baker et al. (2013) assessed changes in behaviour in fish treated with morphine, butorphanol or saline, and either with or without anaesthesia and surgery. Crivelaro et al. (2019) performed surgery under anaesthesia in all fish and compared changes in behaviour between those treated with methadone and saline. Gräns et al. (2014) assessed the impact of buprenorphine on the cardioventilatory parameters of fish either with or without surgical intervention. Harms et al. (2005) compared the impacts of butorphanol, ketoprofen, or saline on the behaviour and clinical pathology of fish undergoing surgery. There is moderate evidence that opioids provide post-surgical pain relief for teleost fish when assessing behavioural indicators of pain, but not when examining cardioventilatory data or clinical pathology.

Summary of the evidence

Baker et al. (2013)

Comparative analgesic efficacy of morphine sulfate and butorphanol tartrate in koi (Cyprinus carpio) undergoing unilateral gonadectomy

Aim: To compare the effect of intramuscular morphine and butorphanol on pain-related behaviours of koi carp (Cyprinus carpio) undergoing surgical coeliotomy and unilateral gonadectomy.

 

Crivelaro et al. (2019)

Behavioural and physiological effects of methadone in the perioperative period on the Nile tilapia Oreochromis niloticus

Aim: To assess the analgesic effect of intramuscular morphine on Nile tilapia (Oreochromis niloticus) undergoing coelomic laparoscopy and surgical ventricular resection.

 

Gräns et al. (2014)

Post-Surgical Analgesia in Rainbow Trout: Is Reduced Cardioventilatory Activity a Sign of Improved Animal Welfare or the Adverse Effects of an Opioid Drug?

Aim: To assess the effect of intramuscular buprenorphine on the ventilation and heart rate of rainbow trout (Oncorhyncus mykiss) undergoing surgical coeliotomy.

 

Harms et al. (2005)

Behavioral and clinical pathology changes in koi carp (Cyprinus carpio) subjected to anesthesia and surgery with and without intra-operative analgesics

Aim: To compare the analgesic effect of intramuscular butorphanol, an opioid, and ketoprofen, a non-steroidal anti-inflammatory analgesic, on the behaviour and clinical pathology of koi carp (Cyprinus carpio) undergoing surgical coeliotomy.

 

Appraisal, application and reflection

There has been a recent surge in demand for successful methods of surgical analgesia for teleost fish. Though there has been debate regarding whether fish neuroanatomy can allow for interpretation of nociception, it has been shown that fish possess nociceptors. Additionally, when presented with noxious stimuli, they display physiological responses such as changes to opercular rate and heart rate and develop avoidance behaviours (Sneddon, 2012). Teleost fish have been involved with invasive surgical procedures as part of biomedical research, aquaculture, and ornamental fish medicine for decades, but postsurgical analgesia is seldom a feature of fish anaesthetic protocols. To maximise animal welfare and optimise postoperative recovery, adequate analgesia should be used which limits behavioural and physiological changes when compared with presurgical values. The opioid class of analgesics are effective at attenuating these changes in response to nonsurgical noxious stimuli in fish and could be beneficial in the perioperative period for painful surgical procedures (Stoskopf & Posner, 2008). The goal of this Knowledge Summary was to investigate if current evidence supports the use of opioids as part of the surgical anaesthetic plan for these fish species.

Current evidence suggests that the most effective option for analgesia in fish are those in the opioid class, particularly mu-opioid agonists (Sladky, 2023). One of the challenges associated with determining effective analgesic plans in fish is the vast interspecies diversity regarding anatomy, physiology, and pharmacology. Species differences can influence the pharmacokinetics and pharmacodynamics of analgesic drugs, such as with the slower metabolism of morphine in winter flounder compared with rainbow trout (Chatigny et al., 2018), and the significant difference in maximum plasma morphine concentration between goldfish and salmon (Nordgreen et al., 2009). It is important to therefore make comparisons between similar species where possible, and that appropriate species selection is carried out when performing research, so that results may be reliably applied. Interspecies differences may also influence the route of administration of analgesic drugs. Administering analgesia via immersion bath, which exposes the gills to a prescribed dose of a soluble drug, can be an effective administration technique, particularly for small fishes in which injection may prove difficult. Intracoelomic or intraperitoneal injection allows for large volumes to be administered, particularly in larger fishes but carries risk of injecting organs and may have reduced absorption compared with intramuscular injection. Intravenous injection is not routinely used in fish due to the intricate nature of their blood vessels (Sladky, 2023). In the appraised studies, there is also wide variety of concentrations of anaesthetic agent used, which may impact on the reliability of results and comparisons between them. It is therefore crucial to compare studies that involve a similar method of drug administration in a similar species to make reliable conclusions.

While the goal of this Knowledge Summary was to assess the literature relating to opioid use for surgical coeliotomy from a clinical perspective, much of the literature related to less-invasive noxious stimuli in laboratory settings and the results of these studies should be acknowledged. Surgical fin clipping is a common procedure in research animals, particularly zebrafish, and has been shown to be a painful procedure leading to increased respiratory rate, lower tank position, and reduced activity levels (Schroeder & Sneddon, 2017), as well as reductions in swimming speed and tank exploration (Deakin et al., 2019). Immersion therapy with methadone reduced these behavioural changes (Deakin et al., 2019), but immersion in butorphanol did not provide significant differences in these parameters compared with a control group (Schroeder & Sneddon, 2017). The studies assessing analgesia for fin clipping may be extrapolated to other surgical procedures such as lumpectomies, but more research in this area would be beneficial.

Due to the common practice of injecting laboratory animals with drugs in research, a large amount of literature focuses on pain associated with injection of noxious chemicals into various locations in fish. Acetic acid is commonly used as a pain-inducing chemical and can cause rubbing of the area injected in rainbow trout (Sneddon, 2004) and catfish (Rodrigues et al., 2019), as well as increased circling and abdominal writhing behaviours (Costa et al., 2023), and changes to locomotory activity in zebrafish (Taylor et al., 2017; Lopez-Luna et al., 2017). Acetic acid injection also reduced interactive group and social behaviours in zebrafish (Rosa et al. 2022). Similar nociceptive effects can be seen with administration of formalin in zebrafish (Magalhâes et al., 2017) and catfish (Rodrigues et al., 2019). The administration of morphine reduced these nociceptive changes in all cases. While very relevant in a laboratory setting, the injection of noxious chemicals is less relevant to a clinical or therapeutic setting.

There are other noxious stimuli that are assessed in pain studies in fish that may not be applicable to the clinical setting, namely electricity and corneal noxious stimulation. Application of an electric shock decreased locomotor activity in zebrafish larvae, which was minimised by treatment with buprenorphine prior to electric stimulus (Steenbergen, 2018). An electric shock produced an agitated swimming response in goldfish, which was inhibited with administration of morphine (Ehrensing et al., 1982). Additionally, an electric shock to the face region caused changes to fin and tail movement in rainbow trout, and these changes were minimised by treating with morphine in a dose-dependent manner (Jones et al., 2012). Application of hypertonic saline to the cornea of zebrafish resulted in a significant change in locomotory activity associated with nociception. This effect was inhibited with administration of morphine, which in turn was inhibited by the administration of the opioid-antagonist naloxone (Magalhâes et al., 2018).

A major consideration when interpreting the results of these studies is the effect of the endogenous analgesic system on antinociception. When piauçu were injected with 3% formaldehyde as a noxious stimulus, there was an increase in locomotor activity. When the fish were exposed to stress by either restraining them (Wolkers et al., 2013), or exposing them to a conspecific alarm substance (Alves et al., 2013), which is a fear-evoking epidermal-released chemical used to signal predatory risk to other animals (Li et al., 2023), this change in locomotor activity was reduced, suggesting a possible antinociception that is restraint or stress-induced. When the opioid antagonist naloxone was given prior to restraint, this inhibition was blocked, indicating involvement of opioid receptors in stress-induced antinociception (Wolkers et al. 2013; Alves et al. 2013). Additionally, zebrafish undergoing fin-clipping surgery exhibited fewer pain-associated behavioural changes when first exposed to acute or chronic stress. When naloxone was administered prior to the procedure and the stress, zebrafish exhibited similar behavioural changes to the stress-free zebrafish (Thomson et al., 2020). Furthermore, when zebrafish were injected with acetic acid, a noxious stimulus, in conjunction with naloxone, the pain response exhibited by increased abdominal curvature was prolonged, indicating the role of endogenous opioids in the recovery from pain (Costa et al., 2019). It is important to consider the possible effects of stress-induced analgesia when interpreting the results of these studies, particularly when repeated conscious handling and restraint is part of the study design. It is advisable that assessment of cortisol levels is performed to ensure stress is not a confounding factor (Jones et al., 2012).

Allocation of participants to treatment groups is described as random in all four studies, but the method of randomisation was not outlined. It is therefore not clear that the authors truly minimised confounding factors with successful randomisation. Three out of four studies specified that they were blind studies, reducing possible biases. In Baker et al. (2013), a single person acting as surgeon and observer was blinded to which injection was administered. In Crivelaro et al. (2019), the observer of recovery period videos was blinded to the treatment group, but it was not outlined whether surgeons were blinded to treatment prior to procedure. In Harms et al. (2005), surgeons were blinded to the treatment group, as treatments were made up to equivalent volumes for body weight, and observers were blinded to both treatment and group. But in Gräns et al. (2014), there was no mention of blinding in the article, and it is not clear whether the observer was aware of the intervention and treatment group of participants.

Ideally the outcomes reported for each study would be based on species-specific guidelines outlining the most reliable indicators of pain, but this type of information is available for very few species. Zebrafish are the subject of many research studies, and as such more detailed data is available describing the most appropriate outcomes when assessing pain in these animals. Measuring activity levels, total distance travelled, and utilisation of space can be reliable indicators of pain in zebrafish (Sneddon et al. 2023). There are also automated methods of measuring these variables, such as the Fish Behaviour Index (FBI), which uses cameras with automated tracking software to automatically measure distance travelled and activity levels at different time points during the study (Deakin et al., 2019). There are concerns about the applicability of these behavioural indicators of pain in zebrafish to other less commonly used species, such as the koi carp, rainbow trout, and Nile tilapia utilised in the appraised studies. There are currently no standardised measures of pain in these species, and further research should be done to create similar guidelines for other common species, so that there can be uniformity in outcome selection between studies.

All four studies involved assessment of behavioural or physiological parameters in the postsurgical period. Baker et al. (2013) compared data recorded prior to intervention with that at multiple intervals postsurgery. Outcomes assessed were respiratory rate, food consumption, activity level, interactive behaviour, and hiding behaviour. Respiratory rate, food consumption, and activity level were found to be the most useful indicators of surgical pain in koi carp, when compared to baseline levels.

Crivelaro et al. (2019) utilised recorded video data for 5-minute intervals at 1, 2, 3, 6, 12, and 24-hours postsurgery. Opercular beat rate, caudal fin beat rate, use of cover, and food consumption were measured. The authors did not find that any of these outcomes reliably indicated surgical pain or its alleviation with analgesia, but the outcomes were only compared between the exposure and control groups and were not compared with presurgical or baseline values. Therefore, behavioural and physiological variation between treatment groups could be confounding results and downplaying their significance.

Harms et al. (2005) measured vertical position in water column, activity level, respiratory rate, and response to food as key outcomes. Additionally, for assessment of clinical pathology, haematocrit, total solids, plasma cortisol, and complete plasma biochemistry panels were compared between presurgical and postsurgical samples. The authors report that vertical position in the water column, activity level, and food response were indicators of surgical pain. Clinical pathology changes were consistent with surgical haemorrhage, and minimal differences were seen between profiles of participants in either treatment group. But haematology and biochemistry profiles were compared only between presurgical and postsurgical samples, and were not compared with species-specific reference ranges, which may place these results within normal limits.

Gräns et al. (2014) was the only study to not use behavioural or observational outcomes in their trial, instead relying on quantifiable data. Cardioventilatory data was monitored for 7 days postoperatively. Electrodes in the water detected bioelectric potentials generated from cardioventilatory muscle activity, which was amplified and processed to record ventilation rate, heart rate, and heart rate variability. But data was recorded for only 4 hours each day, from 12am–4am, at times of least spontaneous muscle activity. Therefore, the immediate postoperative period was not involved, nor were varying time points throughout the day. Additionally, by removing direct observation and behavioural data from the trial, a full assessment may have missed the analgesic effects of the treatment.

In all of the appraised studies (Baker et al., 2013; Crivelaro et al., 2019; Harms et al., 2005; and Gräns et al., 2014), many of the outcomes such as activity level and respiration rate may be affected by the sedative effect of opioids and their tendency to cause cardiorespiratory depression. A profound bradycardia and reduction in cardiac output, as well as a transient decrease in respiratory rate were observed after treatment of morphine in winter flounder (Newby et al., 2007). Similarly, administration of fentanyl to zebrafish larvae resulted in a marked reduction in respiratory rate, which was inhibited by the opioid-antagonist naloxone (Zaig et al., 2021). Gräns et al. (2014) and Baker et al. (2013) attempted to account for this by assessing variables in fish receiving opioids with and without surgery. Without this distinction, it is difficult to determine whether the outcomes were affected by a reduction in pain after administration of opioids, or by adverse effects of the opioids themselves.

Baker et al. (2013) found that both butorphanol and morphine reduced behavioural changes in koi carp undergoing coeliotomy and unilateral gonadectomy. Similarly, Harms et al. (2005) also reported that treatment with butorphanol led to no significant decreases from presurgical behaviours in koi carp undergoing exploratory coeliotomy. These authors concluded that opioids may have some analgesic effect perioperatively for these animals. However, Crivelaro et al. (2019) suggest that methadone may not have an analgesic effect, but merely a sedative effect on Nile tilapia undergoing laparoscopic ventricular partial resection. Finally, Gräns et al. (2014) proposed that buprenorphine causes nondiscriminatory cardiovascular and respiratory depression in rainbow trout, whether undergoing coeliotomy or not.

Within the appraised studies, there is a great deal of variation in species used, opioid intervention administered, and outcomes assessed. Further research needs to be undertaken with a consistent approach to measuring opioid efficacy and focusing on appropriate dosages required to provide surgical analgesia. This should be done by focusing on determining the physiologic impact of opioids on teleost fish so that their analgesic effects can be more accurately assessed, as well as development of more uniform measures of pain in these species. Although there were differences in the studies’ findings regarding the true analgesic efficacy of opioids for teleosts undergoing surgery, and their possible adverse effects, the results of the trials indicate that there is room for opioid analgesia in the anaesthetic protocols for these animals.

Methodology

Search Strategy

 

Exclusion / Inclusion Criteria

 

Search Outcome

 

ORCiD

Shannen Schultz: https://orcid.org/0009-0009-2835-3936

Conflict of Interest

The authors declare no conflicts of interest.

References

1. Alves, F.L., Barbosa-Júnior, A. & Hoffmann, A. (2013). Antinociception in piauçu fish induced by exposure to the conspecific alarm substance. Physiology & Behavior. 110–111, 58–62. DOI: https://doi.org/10.1016/j.physbeh.2012.12.003
2. Baker, T.R., Baker, B.B., Johnson, S.M. & Sladky, K.K. (2013). Comparative analgesic efficacy of morphine sulfate and butorphanol tartrate in koi (Cyprinus carpio) undergoing unilateral gonadectomy. Journal of the American Veterinary Medical Association. 243(6). 882–890. DOI: https://doi.org/10.2460/javma.243.6.882
3. Chatigny, F., Creighton, C.M. & Stevens, E.D. (2018). Updated Review of Fish Analgesia. Journal for the Association for Laboratory Animal Science. 57(1), 5–12.
4. Costa, F.V., Canzian, J., Stefanello, F.V., Kalueff, A.V. & Rosemberg, D.B. (2019). Naloxone prolongs abdominal constriction writhing-like behavior in a zebrafish-based pain model. Neuroscience Letters. 708, 134336. DOI: https://doi.org/10.1016/j.neulet.2019.134336
5. Costa, F.V., Gonçalves, F.L., Borba, J.V., Sabadin, G.R., Biasuz, E., Santos, L.W., Sneddon, L.U., Kalueff, A.V. & Rosemberg, D.B. (2023). Acetic acid-induced pain elicits stress-, and camouflage-related responses in zebrafish: Modulatory effects of opioidergic drugs on neurobehavioral phenotypes. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. 270, 109640. DOI: https://doi.org/10.1016/j.cbpc.2023.109640
6. Crivelaro, R.M., Thiesen, R., Aldrovani, M., Silva, P.E.S., Barros Sobrinho, A.A.F. & Moraes, P.C. (2019). Behavioural and physiological effects of methadone in the perioperative period on the Nile tilapia Oreochromis niloticus. Journal of Fish Biology. 94(5). 823–827. DOI: https://doi.org/10.1111/jfb.13959
7. Deakin, A.G., Buckley, J., AlZu’bi, H.S., Cossins, A.R., Spencer, J.W., Al’Nuaimy, W., Young, I.S., Thomson, J.S. & Sneddon, L.U. (2019). Automated monitoring of behaviour in zebrafish after invasive procedures. Scientific Reports. 9. 9042. DOI: https://doi.org/10.1038/s41598-019-45464-w
8. Ehrensing, R.H., Michell, G.F. & Kasten, A.J. (1982). Similar antagonism of morphine analgesia by MIF-1 and naloxone in Carassius auratus. Pharmacology Biochemistry and Behavior. 17(4), 757–61. DOI: https://doi.org/10.1016/0091-3057(82)90358-6
9. Gräns, A., Sandblom, E., Kiessling, A. & Axelsson, M. (2014). Post-Surgical Analgesia in Rainbow Trout: Is Reduced Cardioventilatory Activity a Sign of Improved Animal Welfare or the Adverse Effects of an Opioid Drug? PLOS One. 9(4). e95283. DOI: https://doi.org/10.1371/journal.pone.0095283
10. Harms, C.A., Lewbart, G.A., Swanson, C.R., Kishimori, J.M. & Boylan, S.M. (2005). Behavioral and clinical pathology changes in koi carp (Cyprinus carpio) subjected to anesthesia and surgery with and without intra-operative analgesics. Comparative Medicine. 55(3), 221–226.
11. Jones, S.G., Kamunde, C., Lemke, K. & Stevens, E.D. (2012). The dose-response relation for the antinociceptive effect of morphine in a fish, rainbow trout. Journal of Veterinary Pharmacology and Therapeutics. 35(6). 563–570. DOI: https://doi.org/10.1111/j.1365-2885.2011.01363.x
12. Li, Y., Yan, Z., Lin, A., Li, X. & Li, K. (2023). Non-Dose-Dependent Relationship between Antipredator Behavior and Conspecific Alarm Substance in Zebrafish. Fishes. 8(2), 76. DOI: https://doi.org/10.3390/fishes8020076
13. Lopez-Luna, J., Al-Jubouri, Q., Al-Nuaimy, W. & Sneddon, L.U. (2017). Reduction in activity by noxious chemical stimulation is ameliorated by immersion in analgesic drugs in zebrafish. The Journal of Experimental Biology. 220(8), 1451–1458. DOI: https://doi.org/10.1242/jeb.146969
14. Magalhâes, F.E.A., de Sousa, C.Á.P.B., Santos, S.A.A.R., Menezes, R.B., Batista, F.L.A., Abreu, O., de Oliveira, M.V, Moura, L.F.W.G., Raposo, R.D.S. & Campos, A.R. (2017). Adult Zebrafish (Danio rerio): An Alternative Behavioral Model of Formalin-Induced Nociception. Zebrafish. 14(5), 422–429. DOI: https://doi.org/10.1089/zeb.2017.1436
15. Magalhâes, F.E.A., Batista, F.L.A., Lima, L.M.G., Abrante, I.D.A., Batista, F.L.A., Abrante, I.D.A., de Araújo, J.I.F., Santos, S.A.A.R., de Oliveira, B.A., Raposo, R.D.S. & Campos, A.R. (2018). Adult Zebrafish (Danio rerio) As a Model for the Study of Corneal Antinociceptive Compounds. Zebrafish. 15(6), 566–574. DOI: https://doi.org/10.1089/zeb.2018.1633
16. Newby, N.C., Gamperl, A.K. & Stevens, E.D. (2007). Cardiorespiratory effects and efficacy of morphine sulfate in winter flounder (Pseudopleuronectes americanus). American Journal of Veterinary Research. 68(6). 592–597. DOI: https://doi.org/10.2460/ajvr.68.6.592
17. Nordgreen, J., Kolsrud, H.H., Ranheim, B. & Horsberg, T.E. (2009). Pharmacokinetics of morphine after intramuscular injection in common goldfish Carassius auratus and Atlantic salmon Salmo salar. Diseases of Aquatic Organisms. 88(1), 55–63. DOI: https://doi.org/10.3354/dao02147
18. Rodrigues, P., Barbosa, L.B., Bianchini, A.E., Ferrari, F.T., Baldisserotto, B. & Heinzmann, B.M. (2019). Nociceptive-like behavior and analgesia in silver catfish (Rhamdia quelen). Physiology & Behavior. 210, 112648. DOI: https://doi.org/10.1016/j.physbeh.2019.112648
19. Rosa, L.V., Costa, F.V., Gonçalves, F.L. & Rosemberg, D.B. (2022). Acetic acid-induced nociception modulates sociability in adult zebrafish: Influence on shoaling behavior in heterogeneous groups and social preference. Behavioural Brain Research. 434, 114029. DOI: https://doi.org/10.1016/j.bbr.2022.114029
20. Schroeder, P.G. & Sneddon, L.U. (2017). Exploring the efficacy of immersion analgesics in zebrafish using an integrative approach. Applied Animal Behaviour Science. 18, 93–102. DOI: https://doi.org/10.1016/j.applanim.2016.12.003
21. Sladky, K.K. (2023). Treatment of Pain in Fish. Veterinary Clinics of North America: Exotic Animal Practice. 26(1), 11–26. DOI: https://doi.org/10.1016/j.cvex.2022.07.003
22. Sneddon, L.U. (2004). Evolution of nociception in vertebrates: comparative analysis of lower vertebrates. Brain Research Reviews. 46(2), 123–130. DOI: https://doi.org/10.1016/j.brainresrev.2004.07.007
23. Sneddon, L.U. (2012). Clinical Anesthesia and Analgesia in Fish. Journal of Exotic Pet Medicine. 21(1), 32–43. DOI:  https://doi.org/10.1053/j.jepm.2011.11.009
24. Sneddon, L.U., Schroeder, P., Roque, A., Finger-Baier, K., Fleming, A., Tinman, S. & Collet, B. (2023). Pain management in zebrafish: Report from a FELASA Working Group. Laboratory Animals. 58(3), 261–276. DOI: https://doi.org/10.1177/00236772231198733
25. Steenbergen, P.J. (2018). Response of zebrafish larvae to mild electrical stimuli: A 96-well setup for behavioural screening. Journal of Neuroscience Methods. 301, 52–61. DOI: https://doi.org/10.1016/j.jneumeth.2018.03.002
26. Stoskopf, M. & Posner, L.P. (2008). Anesthesia and restraint of laboratory fish. In: R. Fish., P. Danneman., M. Brown. & A. Karas., (eds)., Anesthesia and Analgesia in Laboratory Animals. 2nd ed. London, Elsevier,  519–534.
27. Taylor, J.C., Dewberry, L.S., Totsch, S.K., Yessick, L.R., DeBerry, J.J., Watts, S.A. & Sorge, R.E. (2017). A novel zebrafish-based model of nociception. Physiology & Behaviour. 174. 83–88. DOI: https://doi.org/10.1016/j.physbeh.2017.03.009
28. Thomson, J.S., Deakin, A.G., Cossins, A.R., Spencer, J.W., Young, I.S. & Sneddon, L.U. (2020). Acute and chronic stress prevents responses to pain in zebrafish: evidence for stress-induced analgesia. Journal of Experimental Biology. 223(14), jeb224527. DOI: https://doi.org/10.1242/jeb.224527
29. Wolkers, C.P.B., Barbosa Junior, A., Menescal-de-Oliveira, L. & Hoffmann, A. (2013). Stress-Induced Antinociception in Fish Reversed by Naloxone. PLoS One. 8(7), e71175. DOI: https://doi.org/10.1371/journal.pone.0071175
30. Zaig, S., da Silveira Scarpellini, C. & Montandon, G. (2021). Respiratory depression and analgesia by opioid drugs in freely behaving larval zebrafish. eLife. 10, e63407. DOI: https://doi.org/10.7554/elife.63407

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