What to feed herbivorous aquarium fish?
Herbivorous fish in both freshwater and marine aquariums typically have their nutritional needs met through the use of pre-prepared foods containing spirulina. This microalga definitely dominates the diet of herbivorous fish in aquaria. It’s not surprise, given its enormous nutritional and health-promoting values. However, it is worth remembering that this is not the only alga that can be used in fish nutrition. So what to feed herbivorous aquarium fish, aside from spirulina, to make their diet as varied as possible? Learn about the nutritional values of other algae used in aquarium fish nutrition
What algae can you find in aquarium fish foods?
Feeding ornamental fish with algae collected from their natural environment is practically impossible, as you may have guessed. That’s why aquarium fish food manufacturers use algae grown or harvested commercially. As I mentioned earlier, the most popular microalgae in aquarium fish foods is spirulina (Arthrospira platensis). In its composition, the share typically ranges from a few to several tens of percent. Aquarists are generally more familiar with the properties of spirulina compared to algae such as Chlorella, Scenedesmus, Laminaria, Ascophyllum, Undaria, Ulva etc., which are less commonly used in the diet of ornamental fish and more often found in food for consumer fish.
Tropical Super Spirulina Forte with 36% of spirulina, which has been manufactured by Tropical company for many years, is one of the market bestsellers. This is a perfect choice if you want to properly feed herbivorous fish. However, if you would like to diversify their diet with other algae be sure to reach for Tropical 3-Algae Flakes. It contains three species of algae: Chlorella vulgaris, Ascophyllum nodosum and Laminaria digitata. Let’s take a look at their properties. Are they competition for spirulina or rather a great dietary enrichment?
Why use chlorella in aquarium fish nutrition?
Chlorella vulgaris is a unicellular representative of green algae (Chlorophyta). It can be found in both fresh waters and damp habitats. Similar to spirulina, the interest in chlorella stems from its potential use as a protein source for both humans and livestock. In dry matter chlorella can contain 45% to 57% protein rich in essential amino acids. In addition, it is rich in provitamin A (like spirulina), folic acid and iron. This alone makes it a desirable addition in prepared foods, which allows for proper feeding of herbivorous fish. But that’s not all.
| Species: | Average protein content [% dry weight] |
| Arthrospira platensis | 65.0 |
| Chlorella vulgaris | 53.0 |
| Laminaria digitata | 8.5 |
| Ascophyllum nodosum | 9.0 |
Chlorella in fish’s diet means greater immunity
Chlorella has been attributed with health-promoting properties due to the natural immune stimulator beta-glucan present in its cells ‒ beta-glucan and high concentration of chlorophyll (about 2% of dry weight). Beta-glucan increases the natural specific and non-specific immunity of fish. On the other hand, chlorophyll promotes digestion, reduces the number of putrefactive bacteria in the digestive tract, acts as an antioxidant, aids in cleansing the body of toxins, and, when used externally in fish in the form of baths, supports the treatment of skin injuries and infections (aquarists report). In addition, it aids cell repair processes and increases the concentration of hemoglobin in the blood.
Does chlorella have a colour-enhancing effect on fish?
Chlorella vulgaris like spirulina, is a very good source of carotenoids. It may contain about 0.4% of these pigments in dry mass and 80% are red shades. The role of carotenoids in the body of fish is complex and the need for these pigments is constant. However, fish cannot synthesize carotenoids de novo, they must obtain them with food. Colorful breeding varieties of ornamental fish have special requirements in this regard. You can read more about carotenoids and the effects of color-enhancing foods here: Color-enhancing foods for fish – how do they work? oraz How do carotenoids affect fish coloration?
More chlorella means better fat burning
Chlorella in the diet of Plecoglossus altivelis and Nile tilapia (Oreochromis niloticus) reduced excessive fat accumulation in tissues. In its presence, fats were better utilized, which is probably related to its effect on the endocrine system (stimulation of lipolytic hormones). Maintaining chlorella presence below 50% resulted in notable improvements in tilapia growth, accompanied by a decrease in tissue fat content and a simultaneous increase in protein concentration. Chlorella’s properties appear to be beneficial for aquarium fish, which often display fatty internal organs as a result of overfeeding.
What are Kelp algae?
Kelp algae is a trade name of a variety of seaweeds belonging to the brown seaweed. Many Tropical fish foods, including Tropical 3-Algae Flakes, contain two species: Ascophyllum nodosum and Laminaria digitatta. This seaweed stands out due to its rich mineral content, including iodine, iron, potassium, magnesium, calcium, selenium, and phosphorus, with a majority present in easily digestible organic compounds. They are also rich in vitamins (A, B1, B2, B3, B9, C, E) and natural pigments such as fucoxanthin (which belongs to carotenoids) and chlorophyll. And what is most important they have a very high content of dietary fiber.
Dietary fiber from Kelp algae
What needs special attention is the dietary fiber present in this seaweed. It can account for between 33% and 50% of dry matter. This is significantly more than is found in higher plants. There are two types of dietary fiber: insoluble such as cellulose, mannan, xylan and soluble such as alginic acid, fucoidan and laminarin. Among other things, dietary fiber prolongs intestinal transit time, promotes the development of beneficial intestinal bacterial flora, binds bacterial toxins and heavy metal ions. Consequently, it enhances food utilization in fish, fostering improved growth and facilitating body detoxification. Numerous studies indicate the antibacterial and antiviral properties of alginic acid, fucoidan and laminarin and their positive effects on the immune system.
| Component | Ascophyllum nodosum [% dry weight] | Laminaria digitata [% dry weight] |
| Protein | 5.0 | 5.0-12.0 |
| Fats | 3.0 | 0.5-2.0 |
| Carbohydrates, including: Alginic acid Fucoidan Laminarin | 30.0 22.0-30.6 11.4-11.8 2.3-5.9 | 50.0-65.0 32.0 no data 14 |
| Iodine | 0.065 | 0.5 |
Which plant food for aquarium fish should I choose?
Spirulina is certainly the number one algae in fish nutrition. However, it is not the only one that can be used in composing food for herbivorous and omnivorous fish. The nutritional value of chlorella is no different from that possessed by spirulina. On the other hand, the richness of minerals and high content of dietary fiber in Kelp algae, make them highly desirable components of the diet of aquarium fish. Beyond algae, our Tropical foods for herbivorous and omnivorous fish are enriched with nettle, spinach, alfalfa, fruit, oak bark, green peas, and grass.
If you are wondering what to feed herbivorous fish in your aquarium, you can make use of the tips below.
| Food | Algae and other plant ingredients content |
| Super Spirulina Forte Super Spirulina Forte Granulat Super Spirulina Forte Mini Granulat Super Spirulina Forte Chips Super Spirulina Forte Tablets | Spirulina platensis 36% |
| 3-Algae Flakes 3-Algae Granulat 3-Algae Tablets A 3-Algae Tablets B | 12% algae: Chlorella vulgaris, Ascophyllum nodosum, Laminaria digitata |
| Gel Formula for Herbivorous fish | Spirulina platensis 25%, Ascophyllum nodosum 5,4%, Laminaria digitata 4%, Chlorella vulgaris 0,8%, Lithothamnium calcareum 0,8%, oak bark meal 0,7% |
| Soft Line Africa Herbivore S Soft Line Africa Herbivore M | Spirulina platensis 20%, Laminaria digitata 4,1%, Chlorella vulgaris 2,8%, Lithothamnium calcareum 1,2%, young alfalfa sprouts 8,6% |
| Green Algae Wafers | Terminalia catappa min. 2%, Ascophyllum nodosum min. 4%, Spirulina platensis min. 3% |
| Hi-Algae Discs Hi-Algae Discs XXL | Spirulina platensis 36%, Ascophyllum nodosum 8%, Laminaria digitata 6%, Chlorella vulgaris 1,2%, Lithothamnium calcareum 1,2%, oak bark meal 1% |
| Pleco’s Tablets | Spirulina platensis min. 36%, oak bark meal min. 1,0% |
| Spirulina Flakes Spirulina Granulat | Spirulina platensis 6% |
| Microvit Vegetable | nettle meal min. 3%, spinach meal min. 1,5%, Spirulina platensis min. 1% |
| Microvit Spirulina | Spirulina platensis min. 6% |
| Biovit | wheat germ min. 5%, nettle meal min. 2,5%, spinach meal min. 1,5%), Spirulina platensis min. 0,5% |
Ph.D.Eng Aleksandra Kwaśniak-Płacheta
Literature
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Kraan, S. (2012). Algal Polysaccharides, Novel Applications and Outlook, in Carbohydrates ‒ Comprehensive Studies on Glycobiology and Glycotechnology, Chuan-Fa Chang (Ed.), ISBN: 978-953-51-0864-1, InTech, DOI: 10.5772/51572.
Nakagawa H., (1997). Effect of dietary algae on improvement of lipid metabolism in fish, Biomed & Pharmacother, 51, 345-348.
Tartiel, M. Badwy, Ibrahim, E. M., Zeinhom, M., (2208). Partial replacement of fish meal with dried microalga (Chlorella spp and Scenedesmus spp) in Nile tilapia (Oreochromis Niloticus) diets, 8th International Symposium on Tilapia in Aquaculture.
Zahira, Y., Ehsan, A., Afifi, Z., Masita, M., Mohd, S.T., (2014). An overviev: biomolecules from microalgae for animal feed and aquaculture, Journal of Biological Research, 21:6.
