Algae in the diet of ornamental fish are a source of protein and valuable components, which are attributed with pro-health effects, improving fish’s condition, resistance and coloration. Although the different species of algae vary considerably in their protein content and composition, they generally seem to contain all amino acids, which are essential for fish. Algae in the fish diet are thus a much more valuable component compared to other plant raw materials used as a source of protein.
Spirulina (Arthrospira platensis)
The most commonly used algae in fish diet is spirulina (Arthrospira platensis). Initially, the main reason for the interest in spirulina was the extremely high protein content in its cells, which oscillates between 62% and 68%. This is impressive compared to the protein content of meat (15-25%) or soy (35%). In addition, spirulina protein is much more valuable than plant proteins, even those derived from legumes. Spirulina was also found to contain high amounts of pigments such as chlorophyll, caretonoids and phycobilins.
Carotenoid content in spirulina dry matter is estimated at 0.5%. I also contains beta-carotene and xanthophylls. The presence of carotenoids in fish food is essential as they stimulate the immune system, protect valuable cell components from free radicals and some of them are the source of vitamin A. They also play an important role in the process of maturation and reproduction and protect the skin and eggs from UV radiation. Fish cannot synthesize carotenoids, so they must receive them with food. Colourful breeding varieties of ornamental fish are particularly demanding in this respect. The highest content of Spirulina can be found in Super Spirulina Forte (available in the form of flakes, granules, mini granules, chips and tablets), Pleco’s Tablets, Hi-Algae Discs XXL and Marine Power Spirulina Formula Granules. A high content of these algae can also be found in Soft Line Africa Herbivore (20%).
Chlorella (Chlorella vulgaris)
Chlorella is a unicellular, freshwater algae of green algae class (Chlorophyta). In dry matter chlorella can contain 45-57% protein rich in essential amino acids. Chlorella has been attributed with health-promoting properties due to the natural immune stimulator beta-glucan present in its cells. In addition, it has high chlorophyll content, which averages about 2% of dry matter. Chlorophyll (2%) facilitates digestion, reduces the number of putrefying bacteria in the gastrointestinal tract, acts as an antioxidant and helps to cleanse the body of toxins. Applied to fish externally in the form of baths, it supports the treatment of skin wounds and infections (aquarists’ reports). Chlorella is a rich source of carotenoids. In may contain about 0.4% of these pigments in dry matter. Chlorella can be found in the following foods: 3-Algae (available in the form of flakes, granules and sinking and adhesive tablets).
Kelp algae are a mixture of seaweeds belonging to the brown seaweeds that are rich in minerals, including well-absorbed organic iodine compounds, vitamins, dietary fiber, and pigments such as fucoxanthin and chlorophyll. The dietary fiber present in marine algae can account for 33 – 50% of tits dry matter. This is considerably more than is found in higher plants. Kelp algae contain two types of dietary fiber: insoluble (cellulose, mannan, xylan) and soluble, for example, alginic acid, fucoidin and laminarin. Dietary fiber prolongs intestinal transit time, supports development of beneficial intestinal bacterial flora, binds bacterial toxins and heavy metal ions.
Numerous studies indicate the antibacterial and antiviral properties of alginic acid, fucoidin and laminarin and their positive effects on the immune system. Tropical uses two species of marine macroalgae recognized as Kelp algae in its foods, these are: Ascophyllym nodosum and Laminaria digitata. They can be found in the following foods: 3-Algae (available in the form of flakes, granules and sinking and adhesive tablets), Hi-Algae Discs XXL, Soft Line Africa Herbivore.
They are small marine algae that have long been mistaken for corals because of the carbonate structures they produce. Live algae are purple-red in color and grow slowly, accumulating macro- and microelements. They are an excellent source of calcium, magnesium, manganese, molybdenum, iron, fluorine, phosphorus, potassium, iodine, zinc, selenium and cobalt. Due to their organic origin, these elements are highly bioavailable. Lithothamnium calcareum is added to the following foods: Soft Line Africa Herbivore, Hi-Algae Discs XXL.
dr inż. (Ph.D.Eng) Aleksandra Kwaśniak-Płacheta