Current knowledge on use of essential oils as alternative treatment against fish parasites

Abstract

This review article focuses on current knowledge about in vitro and in vivo experimentation relating to use of essential oils (EOs) to combat fish parasites. In addition, we discuss the existing methodologies used in studies to determine the antiparasitic activity of EOs, along with their toxicity and major compounds. The methodological approaches used to describe the anthelmintic properties of EOs were demonstrated. The consistency of their activity and thus their potential use for fish ectoparasites (in vitro and in vivo) and endoparasites (in vitro) control was reviewed. There is a clear need to find EOs and active agents of EOs to treatment in vivo against endoparasites of fish. Thus, progress may be achieved through considering the beneficial aspects of EOs when their complementarity and potentiality are exploited. EOs are therefore viable alternative sources of therapeutic products against fish parasites. On the other hand, use of chemotherapeutics has been increasingly questioned, such that constant environmental and consumer concerns regarding them now exist. The synergistic functions of EOs, in comparison with the action of one or two major compounds of these oils, seems unquestionable. It is possible that their activity is modulated by several molecules of the major compounds. Lastly, EOs are bioactive products that are viable sources of therapy against fish parasites. Although more than 3000 EOs are known, less than 0.4% of them have been tested on fish parasites. Thus, it has become clear that more studies testing these therapeutic alternatives are required, in order to evaluate the antiparasitic potential of other EOs for controlling fish parasites and to maximize their benefits to hosts.