Most experienced cichlidophiles know the optimal food ingredients for the species they keep, especially differentiating between herbivores and omnivores. The digestive system of all cichlids isn’t the same.
For example, mbuna enthusiasts are aware that these very active fish require high concentrations of algae and limited animal protein. In fact, spirulina is often the algae of choice for prepared aquarium foods (e.g., flakes, pellets) made for these rock dwelling species.
Spirulina meal is a proteic dynamo, just slightly lower in crude protein concentration than typical fishmeal (menhaden). Spirulina even exceeds fishmeal, by concentration, in some basic amino acids such as trytophan, valine, and histidine, to name a few.
Fishmeal is increasingly expensive to produce, so spirulina meal might be a welcome volume substitute in aquaculture. Note that I said volume substitute. That means substituting some percentage of fishmeal with spirulina, not replacing it completely.
For more information about spirulina meal properties compared to fishmeal and references to feed studies conducted on various cichlids, see the paper cited below. This research is not difficult to understand compared to most scholarly articles. Give it a read.
Feasibility of the use of Spirulina in aquaculture diets. Rosas, Victor T. et al. Reviews in Aquaculture (2018). https://doi.org/10.1111/raq.12297.