Commercial diets for rotifers vary considerably in nutrient composition and this variation is partly mirrored in rotifers.
The present study was undertaken to investigate the variation in rotifers and rotifer diets used in commercial marine fish hatcheries and to identify possible deficiencies or excess of individual nutrients.
Culture and enrichment diets and unenriched and enriched rotifers were sampled from four hatcheries for Ballan wrasse (Labrus bergylta) and analyzed for nutrients which can potentially fall outside the safe window of supplementation for marine fish larvae.
It is concluded that rotifer diets generally contain appropriate levels of fatty acids and vitamins C and E, while vitamin A, iodine and selenium need more attention. For vitamins D and K and many of the micro-minerals, data on larval requirements are still lacking and these nutrients need further research.
Protein and phospholipid levels are mainly determined by the rotifer's own metabolism and can be low compared to assumed requirements.
December 2015
