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ABSTRACT
Commercial feeds, encoded by letters A, B, and C, with crude protein between 49.1% and 52.9% and crude fat between 13.0% and 22.2% produced especially for percids were fed to European perch (Perca fluviatilis) with an initial body weight of 91.9 g in a 106-day trial during grow-out in a recirculating aquaculture system. A feed manufactured and declared for sturgeon and sea bass farming but traditionally used for percids served as control diet (feed D). In comparison to the best performing percid feed, the sturgeon/sea bass feed D showed similar results. Feed A showed best results in terms of weight gain (14.6 kg), food conversion ratio (1.65), specific growth rate (0.74%/day) and second best survival rates, (98.1%). Differences in slaughter yield were significant only regarding the viscerosomatic index, whereas fillet yield, condition factor (K), hepatosomatic index, and proximate composition of whole body and fillet were comparable for all diets. In conclusion, three different commercial feeds specialized for percid production revealed significantly different production success in a recirculating aquaculture system. On the other hand, a commercial feed with similar composition sold for sturgeon/sea bass also achieved acceptable results.
Acknowledgments
Special thanks to technician Rica Tielebier for water chemistry analyses; to technicians Andreas Tielebier, Stefan Herper, and Daniel Genz for fish husbandry and technical assistance. With best thanks to Hofmann Nutrition (Swiss) for supply of goods. The author is extremely grateful to professional translator Diane Winkler (Petschow, Germany) for intensive editing of the manuscript and linguistic improvements.
Disclosure statement
No potential conflict of interest was reported by the authors.