The evaluation of rapid cooling as an anesthetic method for the zebrafish

As zebrafish became a popular research system in contemporary biomedical research, effective anesthesia, which had low toxicity and high efficacy, was needed. The objective of this article was to evaluate the anesthetic effect of rapid cooling for embryo and larvae zebrafish with ice slush (ice and water admixture). The time to stage 5 anesthesia and maintaining for more than 5 s were detected and compared to MS-222 anesthesia. Besides, the time of recovery from anesthesia, mortality, and the survivability were measured and compared with MS-222 anesthesia. The results showed that anesthesia was generally achieved within 10 s for rapid cooling, which was more rapid than MS-222. The survivability assay demonstrated that rapid cooling was suitable for embryo and larvae zebrafish (1-14 days) and could be used for repeated anesthesia. The most important advantage was that this anesthesia could persist for 10 min and had no mortality. These findings suggested that rapid cooling provided advantages of improved safety, rapid anesthesia, and potentially low mortality rates and could be an effective anesthetic method for scientific research.