Use and Diversity of Medicinal Plants in Aquaculture Practices

Medicinal plants are widely used in Brazilian folk medicine because of their various properties. Their chemical components have attracted the attention of researchers from the field of animal production, particularly aquaculture. This study aimed to analyze the use of medicinal plants in aquaculture practices. The main results showed that medicinal plants have been used in the management of anesthesia, in antibacterial, antifungal, and antiparasitic treatments, and as growth-promoting additives. When the potential of Brazilian flora is considered, little knowledge has been gained about the use of medicinal plants in aquaculture practices, especially when considering the native species, which may represent an important research front in the development of phytopharmaceuticals for the treatment of diseases of cultured aquatic organisms. Keywords—Fish farming, Plant extract, Tambaqui, Tilapia.


INTRODUCTION
In 2016, the world aquaculture production, including aquatic plants, was 110.2 million tons (FAO, 2018). In this context of growing aquaculture activities, Brazilian fish farming reported an 8% growth in 2017, with a total production of 691,700 tons of farmed fish (Peixe & Peixe, The inclusion criteria were scientific articles published in scientific journals in the last 10 years only (2009-2019). Duplicate articles or articles not related to the study theme, as well as abstracts in annals of scientificjournals, dissertations, theses, technical newsletters,and other documents were excluded. The data collected from the articles were inserted into Microsoft Office Excel® 2010 spreadsheets for content analysis and data tabulation.

III. RESULTS AND DISCUSSION
The search in the SCIELO database found only one article based on the descriptor "medicinal plants AND aquaculture," one article for "medicinal plants AND fish farming," no results for "medicinal plants AND tambaqui (Colossoma macropomum)."and two results for "medicinal plants AND tilapia (Oreochromis niloticus)."In CAPES journals, six articles were found for "medicinal plants AND aquaculture,"but only one met the inclusion criteria;ten results were found for "medicinal plants AND fish farming,"but only two were related to the study theme;and two articles each were found for both "medicinal plants AND tambaqui" and "medicinal plants AND tilapia." In the Google Scholar database, 2,300 articles were found for "medicinal plants AND aquaculture," 2,850 for "medicinal plants AND fish farming," 549 for "medicinal plants AND tambaqui (Colossoma macropomum)," and 1,360 for "medicinal plants AND tilapia (Oreochromis niloticus)." After a careful analysis of all Google Scholar search results, only 28 items were related to the study theme, and they were selected for content analysis.  Table 1 shows the use of these medicinal plants in aquaculture practices. The pitanga tree (E. uniflora L.) has edible fruits that are well known and appreciated in Brazil; the infusion of its leaves has applications in folk medicine mainly as a hypotensive, anti-gout, stomachic, and hypoglycemic agent (Auricchio & Bacchi, 2003). In vitro and in vivo tests have shown that extracts from the leaves of E. uniflora L. have several pharmacological properties, such as antidiarrheal, diuretic, anti-inflammatory, and antifungal actions (Almeida, Faria, & Silva, 2012). Fiuza et al. (2011) found that tilapia (Oreochromis niloticus) exposed to different E. uniflora L. extracts and leaf fractions had a vasodilation effect on gills, and toxic effects, such as detachment and desquamation of the respiratory epithelium and hyperplasia of the interlamellar epithelium cells.These effects were more pronounced in those individuals who received the highest concentrations. This study contributed to establish Nile tilapia as a model system for testing active ingredients of plants, such as the vasodilation effect, the effect on cell morphology and on the tissues of the gills, the main respiratory organ of fishes.

3.2Hyptidendron canum(Pohl ex Benth) Harley
Hyptidendron belongs to theLamiaceae family, which consists of herbs, shrubs, and trees, with usually quadrangular branches (Fiuza et al., 2010). Hyptidendron canum is native to the Brazilian savannah (cerrado) regionsand is frequently used in alternative medicine for the treatment of malaria, with anti-inflammatory, antiulcerative, and anti-hepatotoxic actions (Brandão, 1991;Ferri &Ferreira, 1992). Desquamation of the respiratory epithelium, changes in curvature, cell hyperplasia, and vasodilation in the lamellae and in the central vessel of the filaments were the main results that Fiuza et al. (2015) found in the gills of O. niloticussubmitted to ethanol extract and to hexane, chloroform, and ethyl acetate fractions of H. canum. The authors pointed out that H. canumcaused inflammatory processes and injuries that varied according to the dose administered.  Passion flower, of the Passiflora incarnataspecies, has the potential to reduce stress.Its activity is related to the presence of pyronic derivatives, harman alkaloids, and flavonoids, to which sedative and anxiolytic effects are attributed (Dhawan, Kumar, & Sharma,2003). In a study conducted by Oliveira et al. (2010), the authors suggested that passion flower extract could be included in the diet of young tilapia, without prejudice to food consumption and growth. They also reported that the extract changed the morphometry of hepatocytes, suggesting the activity of flavonoids on carbohydrate metabolism, which contributed to increased glycogen levels in liver, particularly in the group that received 100 mg.kg − ¹ of the extract.

Aloe vera (Aloe vera(L.)Burm. f.)
Aloe verabelongs to the Aloaceae family,which includes approximately 15 genera and 800 species. It is a herbaceous plant that grows on any type of soil, but it is better adapted to light and sandy soils and does not require much water ( The authors concluded that the essential oil did not contribute to anti-inflammatory activities; however, an increase in the number of neutrophils was observed. In a study by Oliveira et al. (2018), the authors usedL. origanoidesessential oil to control infections by Aeromonas hydrophila in tambaqui (C. macropomum) juvenilesand found a survival rate of 79.2% after a therapeutic bath with 10 mg.L − ¹ of essential oil; the changes in hematological and biochemical parameters were not significant.

Cockspur coral tree (Erythrina crista-galli L.)
The Erythrinagenus (Fabaceae) contains more than 100 species distributed in the tropical and subtropical areas of the Americas, Africa and Australia (Kone, Solange, & Dosso,2011 1999). Additionally, its bark is used to treat many diseases associated with rheumatism and hepatitis (Hashimoto, 1996). Siqueira et al. (2019) conducted a study to evaluate the anxiolytic effect of E. crista-galli extract in goldfish (Carassius auratus)juveniles, and the authors observed that the extract did not present fish toxicity or mortality.However, it did cause undesirable changes in blood physiological parameters when used in doses above100 mg.L − ¹.Thus, the authors reported that the anxiolytic action was not beneficial to the fish species analyzed. The country almond (Terminalia catappa) belongs to the Combretaceae family.It is an ornamental plant found in several tropical countries, widely used in urban forestry, and present in coastal areas to provide shade (Francis, 1989). Its origin is the coastal areas of eastern India, Indochina, Malaysia, northern Australia, Oceania, Philippines, and Taiwan (Francis, 1989). Studies have demonstrated its bactericidal and fungicidal effects (Costa, Bevilaqua, Morais, & Vieira,2008), and its anti-Helicobacter pyloriand anti-ulcer (Pinheiro , anti-diabetic (Nagappa, Thakurdesai, Venkat Rao, & Singh,2003), and anti-inflammatory (Fan et al., 2004) properties. T. catappa leaves were tested as a growthpromoting additive for N. tilapia (Oreochromins niloticus)juveniles, and the results did not showany positive effects on performance.However, when administered at high levels, it reduced mortality (Santos et al., 2015). In a study conducted by Claudiano et al. (2009), an aqueous extract of dry leaves of T. catappa presented improved efficiency at the dose of 120 ml.L −1 and effectively controlled monogenetic parasites and the protozoan Piscinoodinium pillulare in tambaqui (C. macropomum) juveniles; however, it had no effect against the protozoan Ichthyophthirius multifiliis. Santos et al. (2013) evaluated the performance and behavior of Betta splendens fish growing at different concentrations of T. catappa aqueous extract, and concluded that the extract had no effect on fish performance,whereasfish behavior was influenced by the concentration-that is, higher concentrations caused the fish to be calmer.

Yellow cinnamon(Nectandra grandiflora Ness)
The yellow cinnamon (Nectandra grandiflora Ness) (Lauraceae) is an endemic species of Brazil, predominantly found in the Atlantic rainforest and cerrado biomes (Lorenzi & Brasileira,2002 2017) reported an in vitro analysis in which the essential oil of N. grandifloraexhibited an antiparasitic effect against I. multifiliis, a fish parasite that causes considerable losses in aquaculture. They also suggested that in vivo studies should be conducted to develop a product for the control of I.multifillis.

Species of the Piperaceae family
The Pipergenus belongs to the Piperaceae family, which was described in the 18 th century by Linnaeus. It hasapproximately 12 genera, of which Piper and Peperomia are the most important ones in the Brazilian flora (Medeiros & Guimarães, 2007 essential oils were an alternative source for direct use or for the development of anthelmintic herbal medicines, requiring advanced studies for in vivo treatment.

IV. CONCLUSION
This study on the use of medicinal plants in aquaculture practices demonstrated the diversity of plants used. However, when analyzing the biodiversity of the Brazilian flora across its most diverse biomes, the production of knowledge in this area still presents few results, particularly considering that the tests were conducted with Nile tilapia, the main exotic species grown in Brazilian aquaculture.
The potential of the Brazilian flora for the production of phytopharmaceuticals that can be used in aquaculture still needs further investigation, mainly regarding its use with cultivated native species. While fish farming activities have increased in Brazil, many cases of diseases related to the presence of parasites, endoparasites, bacteria, fungi, and viruses have been reported because of the intensive systems used in fish farming practices. Fish sanitary diagnoses are usually expensive, particularly for small fish farmers. Thus, the use of medicinal plants, especially those producing essential oils and mentioned in this study, has presented great potential for the treatment of aquaculture diseases. Further studies evaluating their use are required to reduce the costs involved in the treatment of these diseases.