Rotifers (Brachionus plicatilis) were reared in sterile filtered
Baltic Sea water (salinity ¼ 17 ‰) in tanks with conical bottoms and
fed with resuspended Nannochloropsis spp. concentrate (BlueBiotech
GmbH, Büsum, Germany). Prior to introducing individuals
to the fish larval tanks, rotifers were harvested from the cultivation
tank and transferred to two conical enrichment-tanks