Tilapia is the most farmed tropical fish species in the world. The emergence of diseases has led to significant loss to tilapia aquaculture over the years. Medicinal plants have been known for use in treating some human diseases and studied in aquaculture to find safe and eco-friendly compounds that are suitable alternatives to the use of antibiotics and chemical compounds. Several parts including seeds, roots, flowers, leaves, and their extracts have been applied in tilapia aquaculture, administrated to fish through injection, immersion, and oral. The biological activities of medicinal plants include enhancement of growth and feed utilization, stimulation of the cellular and humoral immune response, gene expression, and increased disease resistance in tilapia. Despite the potential contribution of medicinal plants, there are some drawbacks including few commercially available medicinal products, no precise data on optimal dose requirements, lack of toxicity studies, and inadequate data on the effects of medicinal plants at the molecular level. This article describes the role of medicinal plants and their forms used to improve growth, feed utilization, immune response, and disease resistance as well as the prospects of medicinal plants in tilapia aquaculture.
Introduction
The emergence of diseases has led to considerable loss to tilapia aquaculture. Over the years, although antibiotics use generally have been successful in treating fish diseases, they can accumulate in the environment as antibiotics residues or in fish tissues and lead to the development of antibiotic-resistant strains. Vaccines are often too expensive and unpractical for widespread use in fish farms, and also, a single vaccine has a specific effect against only one type of pathogen. As a result of the above mentioned complications associated with the use of antibiotics and vaccines, research in recent times has been devoted to finding a safer means to prevent and control diseases in tilapia culture. Out of the numerous findings, the use of medicinal plants is considered one of the best ways to boost the fish’s immunity and could be suitable alternatives to antibiotics. Furthermore, they are cheap, effective with fewer side effects during the treatment of diseases, and above all without any environmental and hazardous problems.
Medicinal plants and aquaculture
Medicinal plants are undoubtedly one of the best alternatives to the use of antibiotics and or vaccines because they possess chemical elements which enhances immunity by specific or non-specific (irrespective of antigenic specificity) routes, thus rendering the animal more resistant to diseases and external aggressions. Medicinal plants comprise of herbs, seaweeds, herbal extracted compounds, spices, commercial plant-derived products, and traditional Chinese herbs. The application of medicinal plants as natural and harmless compounds has potential in aquaculture as a replacement for antibiotics and immunoprophylactic. It is well documented that they have antimicrobial capabilities; the ability to promote growth and improve the immune system and also stimulate appetite and possess anti-stress; and anti-pathogen properties in fish due to active compounds such as alkaloid, terpenoid, phenolic, polyphenolic, quinone, lectin, and polypeptide compounds, and most are effective alternatives to antibiotics, chemicals, vaccines, and other synthetic compounds; thus, they are used as chemotherapeutics and feed additives in aquaculture.
This review seeks to highlight the role of medicinal plants in improving growth, immune response, and disease resistance of tilapia aquaculture and also the factors that seem to affect their application in fish culture studies. We also suggested some interventions that could help promote research to encourage the prospective use and wide scale application of medicinal plants in tilapia aquaculture.
The efficiency of medicinal plants depends on many factors including, dosage, duration, mode, and route of administration. Despite all of the above, there is the need to define the optimal doses and timings of administration of potential medicinal plants. This would help to prevent misuse and also ensure effectiveness since the improper use of medicinal plants can lead to other problems including immune suppression or toxicity effects.
Although fewer studies have dealt with the effects of multispecies medicinal plant formulations in fish culture, the little available evidence indicates that better results are due to the possibility of synergies of energy by the individual plants in the multispecies or combined forms.
Conclusion
medicinal plants and their by-products contain several active compounds such as phenols, polyphenols, alkaloids, and lectins that have been shown to be effective in improving growth, feed utilization, immune responses, and disease resistance in tilapia. However, we suggest the following to help improve research and the application of medicinal plants in fish culture.
Research on the biological effects of medicinal plants at the molecular level as well as their effects on intestinal morphology and bacterial composition is essential in understanding how medicinal plants can contribute to disease prevention and control for the development of suitable therapies.
Sources: Kuebutornye, F.K., Abarike, E.D. The contribution of medicinal plants to tilapia aquaculture: a review. Aquacult Int 28, 965–983 (2020). https://doi.org/10.1007/s10499-020-00506-3
