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Analyzed with regard to their slaughter weights and flesh quality 78-month-old diploid and triploid rainbow trout (full sibs) were reared together in a pond after tagging at an age of 12 months. Triploids had higher body weights and carcass percentages than diploids (6 kg vs 4 kg and 66% vs 52%). Triploid fish also displayed lower electrical conductivity values and darker (L* value) and redder (a* value) flesh color. The fillets of the triploid trout contained more crude fat and less moisture than the diploids (6% vs 3% and 68% vs 74%, respectively). No effect of ploidy was found with regard to the protein contents. Triploid rainbow trout had larger mean white and intermediate muscle fiber areas than diploid fish in the dorsal and pelvic fin regions. In the pelvic fin part, the white muscle fiber areas were larger than in the dorsal fin part. In conclusion, adult triploid rainbow trout grow faster especially by fiber hypertrophy and have better flesh quality parameters than diploid fish.

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The provision of fry and fingerlings, independent of the natural spawning season, can facilitate the implementation of innovative rearing strategies also in pike perch (Sander lucioperca L.). As strict pharmaceutical acts or codes of conduct for organic aquaculture can constrain fish farmers in inducing spawning with hormonal applications, this study intended to develop protocols for advanced and postponed spawning just by simple photo‐thermal treatments. After spending between 31 and 61 days at temperatures below 10 °C, different groups of pike perch spawners were treated with light and temperature programmes to advance spawning. Reproduction could be induced successfully 2 months before the natural spawning season when the mating pairs spent 43 or more days below 10 °C, followed by a maturation phase of 44–68 days at 15 °C and 16 h illumination per day. Advanced spawning could be documented for 32 out of 35 females (91%) that underwent photo‐thermal treatments. Mean commercial fecundities up to 24% and average rates of developing eggs of 65% were observed in advanced spawning groups. Coldbanking of mature females allowed to postpone spawnings for 2 and 3 months. However, no egg development could be recorded in these treatment groups.

1,2,5,6,9,10-hexabromocyclododecane (HBCD) is a brominated flame retardant consisting of a mixture of diastereomeric pairs of enantiomers that is a known omnipresent, environmental contaminant. The present study investigated the possibility of bioisomerization of HBCD stereoisomers. Therefore, mirror carps (Cyprinus carpio morpha noblis) were exposed to pure (+)- and (-)-gamma-HBCD, randomly sampled biweekly over a period of three and a half months and the fillets were subjected to enantiomer-specific determination of HBCD. Considering the background contamination of the fish at the beginning of the feeding period, significant enrichment of the respectively fed gamma-enantiomer was already detectable after two weeks of exposure. However, no significant enrichment of the respectively expected alpha-enantiomer was observed within this period. Thus, no evidence for the isomerization of HBCD stereoisomers was found in mirror carp under the applied conditions.