Diagram of the course of the tested environmental factors: specific conductivity (C) and temperature (T) during 339 days in breeding group and tank I containing two females and one male of Notopterus notopterus. 20 spawnings of the female No. 1 were observed within a 5-month period. The breeding experiment was started after 3 months of acclimatization period. A swollen belly of the female was first observed after one month (arrow). * Asterisks refer to observed spawnings.