Selection of marine species and meals for cephalopod feeding based on their essential mineral composition

A quantitative analysis of the essential mineral content (mg kg−1 dry weight) was carried out in 31 samples, including molluscs, crustaceans, fish and meals in an attempt to identify those most suitable for formulating cephalopod diets. The mineral ratios (MR: content in the test sample/content in whole Octopus vulgaris) were used as index of nutritional quality. Both crustaceans and oysters presented an optimal profile that covered the macro- and microelements composition of O. vulgaris. These samples differed from the rest by their higher Ca, Mg, B, Cu and Zn contents based on a principal component analysis. Fish were deficient in macroelements, such as Na (MR: 70–420 g kg−1) and Mg (MR: 220–690 g kg−1), but would be good source of K, Ca and P. Most fish were also deficient in Fe, Zn and Cu, although the copper content would be the most affected (MR: 3–130 g kg−1). Fish and krill meals showed a high content of Ca and P, although both would be deficient in Na (MR: 440–470 g kg−1) and Cu (130–540 g kg−1), along with K, Fe and Zn in krill and Mg and B in fish. Among the plant meals, sunflower and soybean were the most appropriate, presenting higher total content of minerals and MRs above 1000 g kg−1 for all minerals, except Na, Cu and Zn.