For feces collection two different methods were used, consecutively. Final guts of the fishes were stripped by an abdominal massage for a period of 10 days every second day and 7 h after feeding. All samples of one replicate were pooled in one plastic beaker and were deep frozen immediately at −18 °C. After a recreation period of 14 days all
fishes were killed 7 h after feeding. The gut contents were sensitively dissected from the final gut, as described by Dietz et al. (2012, 2013).
For both feces collection methods apparent digestibility coefficient (ADC) was determined for dry matter (DM), organic matter (OM), crude ash (CA), crude protein (CP) and energy.