Spirulina Fish Foods

Spirulina is dried Arthrospira microalgae used in aquarium feeds as a high-protein, pigment-rich vegetable ingredient for herbivores.

What spirulina is

Spirulina is the dried biomass of filamentous cyanobacteria (blue-green algae). The organisms cultivated commercially are now classified in the genus Arthrospira, which was formerly placed within Spirulina; the common species include Arthrospira platensis and Arthrospira maxima. The trade name spirulina has persisted even after the taxonomic reassignment, so feed labels often list it simply as spirulina.

Nutritional profile

Dried spirulina is a concentrated protein source. According to Wikipedia, the dried biomass contains roughly 57% protein by weight. It also carries vitamins and a range of carotenoid pigments. These properties make it a useful component in formulated fish feeds rather than a complete diet on its own.

Pigments and coloration

Spirulina supplies carotenoid pigments such as zeaxanthin. UF/IFAS notes that spirulina is used among natural pigment sources in ornamental fish diets. Carotenoids are deposited in fish tissue and contribute to red, orange and yellow coloration, which is why algae-based ingredients are common in color-enhancing feeds.

Use for herbivores

Plant-based ingredients suit herbivorous and omnivorous species that graze on algae in the wild. In aquarium feeds spirulina appears in flakes, sinking wafers and gel foods aimed at algae eaters such as plecos and other grazing fish. It is one of several vegetable ingredients used alongside seaweed and other plant matter.

Inclusion levels

• UF/IFAS lists spirulina as a natural pigment source at about 0.5-1.0% of the diet.
• Wikipedia reports a safe use level of up to 2% spirulina per day in aquaculture feed.
• Higher inclusion appears in dedicated algae and herbivore formulations.

Aquaculture applications

Beyond the home aquarium, spirulina has been fed to a wide range of farmed aquatic species. Wikipedia lists carp, tilapia, catfish, shrimp, milkfish and several marine fish among species that have received spirulina in their feed, reflecting its established role as a supplementary feed ingredient.

Practical notes

Spirulina-based foods are typically offered as part of a varied diet. As with any prepared food, only the amount fish consume should be added, since uneaten food contributes to waste and can degrade water quality over time.