Pond and ornamental fish such as koi, goldfish, sterlet (a small subtype of sturgeon) and others appreciate a tasty and balanced diet. This best includes optimally digestible (fish) protein and important omega fatty acids. High-quality fish feed is ideally made from suitable and easily digestible ingredients. Various crustacea and shellfish such as krill, daphnia, shrimps and amphipods are often included, as well as some protein products such as mealworms, silk worms and spirulina. Spirulina is a type of cyanobacteria that, in contrast to algae, does not contain iodine. Soybean meal is not digested as well by pond and ornamental fish. The food should also contain no preservatives, if possible.