The objective of this study was to determine differences in relevant parameters of the basic chemical composition of flesh (descriptors: dry matter – DM, crude proteins – CP, net proteins – NP and net muscle proteins – NMP, fat – F, ash – A) of communal stock of diploid (2n) and triploid (3n) tench (Tinca tinca L.) of the same origin, in relation to sex (F: female vs. M: male) and age (T<sub>3</sub>: 36 months, after overwintering vs. T<sub>3+</sub>: 42 months, after one summer in the pond). Altogether 137 siblings of tench were studied. The basic chemical composition of flesh of 2n and 3n tench of T<sub>3</sub> age was found to be nearly the same. The only significant difference (P < 0.05) was found in DM content in diploids (5.7% higher DM content in females). Marked changes in the basic chemical composition were related to the increasing age of tench: after one summer in the pond (from T<sub>3</sub> to T<sub>3+</sub>) the DM content increased significantly in all groups of tench (by 5.4% in 2n females, P < 0.05; by 6.5% in 2n males, 9.9% in 3n females and by 7.4% in 3n males, all at P < 0.01). The content of nitrogenous substances was found to increase significantly (P < 0.01) in flesh of 2n males: CP by 3.2%, NP by 4.2% and NMP by 3.3% and in flesh of 3n males: CP by 7.0%, NP by 6.6% and NMP by 7.3%. Muscles of 3n females contained 107.3% higher fat content (P < 0.05). The proportion of ash decreased in 2n and 3n by 2.5% and 1.7%, respectively (P < 0.05). The flesh quality of T<sub>3+ </sub>tench after one summer in the pond was higher if compared with that of T<sub>3 </sub>tench after overwintering. Related to the ploidy level, more favourable chemical composition of flesh and more favourable flesh quality were found for triploids of T<sub>3+</sub> age.
Chemical composition of flesh of diploid and triploid population of tench (Tinca tinca, Linnaeus 1758)
