The aim of the research was to observe the process of copper and lead accumulation in tissues of adult females of the common carp, during a long-time (3 years) dietary exposure to these metals in pond conditions. The fish were divided into 3 groups, which were fed with control pellets (control group) and pellets contaminated with lead (group Pb, 68.4 mg Pb kg À1 dry weight) or copper (group Cu, 153.1 mg Cu kg À1 ) for three exposure periods: the first, the second and the third vegetation seasons.Quite a different profile of tissue metal accumulation was observed for copper and for lead in female carps. Copper accumulates mainly in the liver (205.4 AE 35.2 mg kg À1 ), reaching values 70 times higher than in control, and 300 times higher than in some other tissues, while lead accumulated mainly in the kidney (1.7 AE 0.25 mg kg À1 ) and intestine (2.2 AE 0.2 mg kg À1 ). Even when exposed to Cu or Pb for three consecutive seasons, the carps studied did not accumulate these metals in the muscles at the level dangerous for human health in case of ingestion.

During a long-term 3-year dietary exposure of mature carp females to lead, its bioaccumulation in the brain, changes in the neurohormonal activity at the level of the hypothalamus and the pituitary gland as well as the growth and maturation of ovaries were analysed. Moreover, an analysis of the effectiveness of hormone-stimulated spawning during two subsequent spawning seasons was carried out. The results of the analyses show that chronic exposure of maturing and mature carp females to lead in feed results in its accumulation in the brain (1.365 lg g À1 ). This impairs the endocrine activity of the hypothalamus, which is manifested by, among others, an increased secretion of dopamine and impaired spontaneous secretion of luteinizing hormone (LH). The observed decrease in the concentration of gonadotropin in blood inhibits vitellogenesis, which is manifested by a lower degree of the maturity of oocytes, lower fecundity (as measured by egg number, egg weight, egg maturity and egg survival) and lower gonadosomatic index values. The final negative impact of lead is the impairment of reproductive functions, as manifested by a smaller number of spawning females and in their lower fecundity during spawning.