Herbs in fish nutrition Aleksandra Kwaśniak-Płacheta, PhD

HERBS

IN FISH NUTRITION

Aleksandra KWAŚNIAK-PŁACHETA, PhD

Hydrobiologist, expert on feeding and breeding of ornamental fish, aquarium enthusiast. A highly recognized speaker of many aquarium training courses and symposiums. Author of articles published in domestic and foreign magazines including ”Nasze Akwarium”, ”Magazyn Akwarium”, ”Planeta Zwierząt”, ”Tanganika”, ”Fauna & Flora”, ”Pet Market”, ”Aquafeed Magazine”, ”Pet Worldwide” and various publications of Wrocław Aquarium Association.

Herbal medicine (or phytotherapy) is a type of treatment that uses plants. The first documented reports of human use of herbs to treat various ailments date back five thousand years. However, it can be assumed that people had used the beneficial properties of plants to help them with numerous conditions much earlier. People had been gathering this knowledge and passing it on to the next generations and with time they started to write it down.

The Sumerians recorded their prescriptions and information about medicinal plants in cuneiform script on clay tablets. The oldest Chinese herbarium (Pent-Sao book) dates back to the XXVIII century BC. It contains descriptions of plant remedies (juices, infusions, decoctions, powders, ointments and wines). In Egypt, information about herbs has survived on temple walls and papyri. Ebers papyrus seems particularly interesting. This more than 20-metre-long scroll was written down around 1550 BC. It contained almost 800 recipes for medicines, which were mainly based on plant materials, including garlic (Allium sativum), mint (Mentha sp.), aloe (Aloe vera) and greater celandine (Chelidonium majus). The most prominent ancient physician and expert on plant medicines was Hippocrates of Kos (460-377 BC). Another one was Dioskurides (1st century BC). Some of the herbs he described are still used today – e.g. chamomile (Matricaria chamomilla), valerian (Valeriana officinalis), comfrey (Symphytum officinale) or lemon balm (Melissa officinalis). In the 2nd century AD, Galen introduced various forms of medicines made from fresh or dried herbs.

Alkaloids give the plant a bitter taste, which is probably to protect it from eating by animals. Some animals, by eating plants rich in alkaloids, acquire poisonous properties, which protects them from attack by predators. Many alkaloids are used in medicine. The most popular include: ephedrine (among other things, increases metabolism, stimulates the heart muscle and respiratory center), quinine (analgesic and antipyretic effects, and also deadly for malarial spores), codeine (cough suppressant), caffeine (reduces the feeling of sleepiness and fatigue, speeds up heart rate), theine (regulates intestinal movements and relieves pain).

Phenols are strong antimicrobial agents, found in oak bark, fruit, Ketapang leaves, chicory, and elderberry, arnica, and others.

Flavonoids are colourful compounds found in almost all plants. Their main groups are yellow flavones and colored anthocyanins (their color changes from orange, through purple, to violet – depending on the pH of the cell sap). They protect the plant from insects and fungi. They are strong antioxidants.

Tannins are compounds of varying chemical composition, very common in plant tissues, but generally found in low concentrations. They protect plants against pests and pathogens (bacteria, fungi, viruses). The best known is a common tannin, which is found in very high amounts in Ketapang leaves and oak bark. We experience the tart taste of tannin every day when drinking our tea. The bactericidal effect of tannins is due to their ability to bind proteins. Tannins are a component of black waters. Thanks to their disinfectant properties, they are responsible for low concentrations of microorganisms in the water environment.

Glycosides are a group of organic compounds with a very complicated chemical structure, in which sugar combines with alcohols, phenols, sulfur compounds, etc. The most important group of glycosides are flavonoids, cardiac glycosides and phenolic glycosides. They all play an important role in herbal medicine.

The fall of Roman civilization resulted in a decreased interest in science. And while herbs have not been totally forgotten, a lack of observation and research has stunted the development of herbal medicine. At that time alchemy had its golden age. In the dark ateliers, the search was on for the Philosopher’s Stone, an extraordinary substance that would change common metals into gold. Alchemists wanted to create a miraculous elixir to prolong youth, life and cure all diseases. They never managed to fulfill their dreams, but they made outstanding contributions to chemistry. The 16th century belonged to Paracelsus, who was the first to notice that some ”chemical bodies” in plants were responsible for their healing properties. And it was this chemical body that had to be extracted from the plant. The first active substances were isolated from plants in the early 19th century. In 1815, Friedrich Wilhelm Adam Sertürner identified the active ingredient in poppy and named it morphine. In 1818 Pierre Joseph Pelletier and Joseph Bienaimé Caventou isolated strychnine from the seeds of the strychnine tree (Strychnos nux-vomica) and two years later chinin from the bark of the Cinchona tree (Cinchona succirubra). In 1820, Friedlieb Ferdinand Runge obtained caffeine from coffee (Coffea arabica) seeds. The most important groups of active plant compounds include: alkaloids, phenols, glycosides, flavonoids, tannins, essential oils, mucilages and pectins.

HERBAL MEDICINE TODAY Currently, almost half of the medicines produced in the world contain active substances derived from plants or synthesized on their basis. The medicinal properties of many plant species have been scientifically confirmed, and the chemical structure of many plant-derived active substances has been identified. Interestingly, while doing this research, it turned out that many plants that have been used for centuries for specific ailments may have much broader uses. An example would be tannins. They have been known for their anti-inflammatory and antibacterial properties. However, in-depth studies have revealed their potent immunostimulatory effects.

HERBS IN ANIMALS NUTRITION Herbs have not only been used to treat humans, but they are also commonly used as a nutritional supplement in foods for livestock and pets. Their flavor is tempting for many animals, so their presence in the feed increases intake, which is eagerly used in livestock farming, where rapid weight gain is important. Herbs increase the palatability of food and the appetite of animals, improve digestion. They also have an anti-inflammatory, diarrheal, bacteriostatic effect and have a positive influence on general health. HERBS IN FISH FOOD For the breeding and raising consumer fish, substances with immunostimulatory properties may be the alternative to drugs. The most popular include lipopolysaccharides (LPS), extracted from the cell walls of various Gram-negative bacteria pathogenic to fish, and beta-glucans, most commonly extracted from yeast cell walls. However, polysaccharides, vitamins and plant extracts can also affect non-specific immunity in fish. When used in aquaculture, herbs enhance weight gain and exhibit antimicrobial properties. Chinese medicine is rich in numerous species of herbs with immunostimulating properties. One of the most famous Chinese herbs is Mongolian milkvetch (Astragalus membranaceus). The main active substances in the root of this plant are polysaccharides, which support non-specific immunity. This was confirmed by studies conducted on carp (Cyprinus carpio) and Nile tilapia (Oreochromis niloticus). The carp given the Mongolian milkvetch extract better fought infection caused by Aeromonas hydrophila. Another interesting plant used in Chinese medicine is the Japanese honeysuckle (Lonicera japonica), often grown also as an ornamental plant. It is credited with having a beneficial effect on the immune system. In Nile tilapia, administration of Japanese honeysuckle increased macrophage activity and reduced mortality in comparison to fish that did not receive it. Using mixtures of different species of herbs gives very good effects in fish. In this case, the active substances from them interact, so they work together more strongly (synergy), as well as the body itself may react more strongly to treatment with several different herbs. Such a synergistic effect has been observed when fish were treated with a mixture of Chinese herbs, designated C-UPIII, consisting of Chinese rhubarb (Rheum officinale), green chiretta (Andrographis paniculata), woad (Isatis indigotica) and Japanese honeysuckle (Lonicera japonica). The mixture given to guppies (Poecilia reticulata) increased their survival rate during infection with Tetrahymena pyriformis. This is just one of many examples of combinations of different herbs used in fish. Numerous scientific studies have also investigated the use of Indian herbs in fish health prevention.

One of the well-known plants from this culture is the emblic (Phyllanthus emblica), also known as myrobalan. This plant shows strong antioxidant, antifungal, anti-inflammatory and antibacterial properties. In addition, the fruit of this plant is known for its very high vitamin C content. The aqueous extract of myrobalan fruit showed positive effects on the immune system of Nile tilapia (Oerochromis niloticus). Also, Indian lilac (Azadirachta indica), known as neem, has shown similar effects in experiments with tilapia. Researchers also looked at species such as smooth licorice (Glycyrrhiza glabra), mistletoe (Viscum album), nettle (Urtica dioica), and ginger (Zingiber officinale). Extracts from these plants were administered to rainbow trout (Oncorhynchus mykiss) with positive outcomes.

HERBS IN AQUARIUMS Herbs are also present in aquaristics. They play an important role in the preparation of water and make an ingredient of both ready-made and home-made foods. In its aquarium fish foods Tropical uses: garlic, nettle, aloe vera, oak bark and Ketapang (Terminalia catappa). It is worth remembering that aquarium fish foods contain plants (spinach, peas, grasses) and algae (spirulina, chlorella, Kelp algae) rich in active substances that regulate metabolic processes, detoxify the body and positively affect the overall health of fish.

COMMON NETTLE (Urtica dioica) Nettle contains minerals, amines, glycosides, pectins and tannins. It has anti-inflammatory and immunostimulating effect. In poultry studies, capsaicin (a compound we know from hot peppers, responsible for their pungent taste), antimicrobial cinnamaldehyde and antiseptic carvacrol were found to have positive effects on the poultry’s growth. This became the premise for experiments on fish. Scientists studied the effects of different doses of nettle in the diet of juvenile and adult Labeo victorianus, an endemic carp fish inhabiting the Lake Victoria catchment in Africa. The results confirmed the beneficial effect of nettle on the immune system of fish and its anti-infective properties. In addition, nettle components can affect pathogenic and non-pathogenic bacterial species in the digestive tract of fish. This leads to a better utilization of the food, which accelerates growth and facilitates immunity. Nettle also had beneficial effects on the immunity of rainbow trout (Oncorhynchus mykiss) and beluga sturgeon (Glycyrrhiza glabra). It is worth noting that non-specific immunity, which is vertebrates’ first line of defense against pathogens, plays more important role in fish than in mammals. Hence, enhancing non-specific immunity of fish through various natural immune stimulators is a very important issue. Especially when it comes to reducing the use of synthetic drugs, including antibiotics. Common nettle is added to Malawi Flakes (3.75%), Malawi Chips (4%), Cichlid Color (2.5%). Its active substances regulate digestive processes, prevent inflammatory conditions of digestive tract and strengthen immunity of fish.

GARLIC (Allium sativum) Garlic is a flavorful spice and herb plant known to all and used in folk medicine for ages. Garlic cloves contain sulfur compounds, including allin, which breaks down after tissue damage to form allicin. It is to allicin that garlic owes its strong antibacterial action and characteristic smell. Garlic also contains flavonoids, pectin, mucilage, a number of vitamins and trace el-

ements. It is very readily added to foods prepared at home, especially for discus and other South American cichlids that are often attacked by parasites and suffer from inflammatory disorders of digestive tract. Scientific research has confirmed the medicinal properties of garlic, including the bactericidal and bacteriostatic effects of sulfur compounds (allicin and diallyl trisulfide). In Tropical’s wide offer of foods there are several products containing garlic. The leading food with this ingredient is D-Allio Plus, available as flakes and granules. It can be fed to all aquarium fish. It contains 5% garlic concentrate. And what do the experiments conducted on fish say? Application of garlic in doses of 0; 0.05; 0.1; 0.5; 1.0 g per 100 grams of food to rainbow trout for 14 days resulted in a significant decrease in mortality of Aeromonas hydrophila-infected fish. Doses of 0.5 and 1.0 grams per 100 grams of food reduced fish die-off to 4% compared to 88% in the control group. In addition, an increased growth was observed due to better food utilization. Similar observations were made when feeding garlic to the African catfish Clarias gariepinus. Garlic, admittedly in smaller quantities, can also be found in foods: Gel Formula for Omnivorous Fish (3.5%), Soft Line America (4.5%), Soft Line Africa Carnivore (4.5%), Discus Gran D-50 Plus Baby (5%), Discus Gran Wild (5%).

OAK BARK (Quercus sp.) Oak bark meal has been used in three Tropical products: Gel Formula for Herbivorous Fish (0.7%), Pleco’s Tablets (1%) and Hi-Algae Discs XXL (1%). They are all intended for feeding herbivorous fish, including Loricariidae and other species that use wood as a food source. Their specially adapted teeth and mouth equipped with a sucker allow them to rub off branches and other tree fragments submerged in water. The bacteria in the fish’s gut are involved in digesting this food. No doubt oak bark meal found its way into these foods as a source of fiber and an important component of the diet of wood-eating Loricariidae. It is also worth noting the health-promoting properties of this ingredient. Oak bark has been found to contain large amounts of tannins, polyphenols, flavonoids, fatty acids, vitamins, including an exceptionally large amount of vitamin E and sterols. In herbal medicine, oak bark has been used for digestive problems, skin inflammation and urinary tract infections. It is attributed with antibacterial, anti-inflammatory and anti-diarrheal properties.

ALOE VERA It is one of the many species of aloe whose properties for humans and some domestic animal species have been so well investigated. It is used for injuries, skin inflammation, light burns, digestive disorders, constipation, decreased immunity and many other health problems. The properties of aloe vera can be attributed to a large amount of polysaccharides present in the gel obtained from the leaves of this plant. Aloe vera administered to carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) together with food resulted in better utilization of the food, which led to more intensive growth. At the same time an increase in immunity was observed when aloe vera was administered to Brycon amazonicus fish. Studies conducted on juveniles of pacu (Piaractus mesopotanicus) have shown the great potential of this plant. It was found that the addition of aloe extract (1% and 2%) activated the mechanisms responsible for non-specific immunity in fish. The study also included the catfish Clarias

gariepinus, in which the addition of aloe vera clearly intensified growth. In addition, catfish showed greater survival under adverse low pH conditions compared to the control group. Apart from 12% algae, 3-Algae also contains aloe vera extract (2%). This food is available in the form of flakes, granules, sinking tablets and adhesive tablets, which gives the possibility to feed many species of fish. Aloe extract has been also added to many water treatment products such as Esklarin with Aloe and Sanital with Aloe, where its soothing effect on abrasions and other skin injuries is used.

PREPARATION OF WATER Herbaceous plants also prove useful for preparing water for ornamental fish. Commonly used Polish plant species include common oak (Quercus robur) and sessile oak (Quercus sessilis), as well as cones of black alder (Alnus glutinosa) or grey alder (Alnus incana), extremely rich in tannins, flavonoids, phenols, terpenes and phytoncides (substances with antibiotic effect). Tannins and organic acids released from oak leaves and alder cones cause a slight decrease in water pH. Tannins give the water a golden brown color, and if we put too many leaves or cones the water turns dark brown, while their bactericidal properties allow to get rid of excess bacteria from the aquarium environment. Similar properties are presented by sea almond (Terminalia catappa) leaves. SEA ALMOND (Terminalia catappa) In nature sea almond can be mostly found in Southeast Asia. The Ketapang leaves came to aquariums from Asian folk medicine, where they are used to treat liver and skin diseases. The properties of this plant have been confirmed by scientific studies. Extracts obtained from Terminalia catappa have anti-inflammatory, antioxidant, anticancer effects and protect the liver from hepatotoxins. Although scientists managed to isolate many active substances from

Ketapang leaves and recognize their properties, not all mechanisms of action have been fully researched. When placed in an aquarium, dry Ketapang leaves release various substances into the water, including dyes that give the water a golden brown color. At this point, almost every aquarist knows that Ketapang is a source of humic compounds and extremely high amounts of tannins. In addition to these, alkaloids, terpenes and phenols etc. also enter the water. The high concentration of these substances in Ketapang leaves is probably a defense mechanism of the tree, protecting its leaves and fruits from parasite attacks. Substances released into the water greatly limit the growth and reduce the concentration of bacteria, fungi and protozoa in the aquarium environment. However, unlike medicinal preparations, they do not impair biological filtration. Humic acids and tannins released to the water slightly decrease the pH of the water. Ketapang allows to create in a home aquarium conditions similar to natural ones, typical for soft, slightly acidic and tannin-rich waters. Asian ornamental fish farmers use Ketapang to protect eggs from mold. To do this, they apply the leaf to a working filter or directly to the spawning tank. With this treatment, hatchability and hatchling survival rates increase significantly. Due to the antiseptic (disinfectant) properties of Ketapang, it is also used in situations of increased risk of damaging the external layers of fish, i.e. after water changes, after transport and during the period of fish acclimatization in a new tank. Substances released from Ketapang leaves accelerate wound healing, regeneration of mucous membranes and fish fins. Tannins and humic acids also inhibit the development of blue-green algae,

so undesirable in aquariums. Ketapang leaves used in experimental cultures of tilapia (Oerochromis niloticus) contributed to a large reduction in the concentration of Aeromonas bacteria and Trichodina protozoa, and also reduced egg mold. Tropical offers a product in the form of crushed Ketapang leaves in convenient sachets. It can be easily applied to the filter or put in any place of the tank. Furthermore, Ketapang has been used as an ingredient in the food for algae-eating Loricariidae – Green Algae Wafers – and in sticks for freshwater shrimps: Shrimp Sticks. To both products, 2% of the meal obtained from the leaves of the almond tree has been added.

SUMMARY Numerous studies indicate that herbs can be used to increase the natural immunity of fish, which gives hope for reducing the use of synthetic drugs, including antibiotics, in commodity farms. Drawing on this knowledge, we can use herbs in ornamental fish nutrition and water treatment products for aquarium.

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