Partial fishmeal and oil substitution with a microorganism mix as an innovative diet for rainbow trout (Oncorhynchus mykiss) and pike-perch (Sander lucioperca)

Abstract

Fishmeal and oil are regarded as byproducts resulting from fish processing. However, the procedures are hypothesized to be an ecological harm for maintaining the balance of the aquatic ecosystems. This study aimed at characterizing an innovative algae–yeast mix for a partial substitution of fishmeal and oil in fish feed. The microorganism mix consisted of the cyanobacterium Arthrospira sp., the microalgae Crypthecodinium cohnii, and the yeast Rhodotorula glutinis to create a balanced nutritional composition with an enrichment of bioactive compounds for inducing positive health effects in selected fish species. Such a modification can also be interpreted in terms of a positive (human) nutritional effect. From an ecological point of view, all these microorganisms can be cultivated without minimum effort. In fish feeding trials, pike-perch (Sander lucioperca) and rainbow trout (Oncorhynchus mykiss) were taken for evaluating the feed acceptance, fish health, and fish filet quality. The study revealed a successful feed development, which resulted in healthy organisms depending on the species and compared to conventionally fed organisms.