No detailed citation.
| Species | Development state | Trait | Primary Data | Secondary Data |
| Gymnocephalus cernua | Male | Onset of spermatogenesis | Two periods of gonad activity are observed in males in the course of the year; spring and autumn wves of spermatogenesis occur [Winter conditions provoke a considerable slowing down of spermatogenesis, ending in most specimens (81%) with its cessation in the phase of reprodcution of spermatogonia | ['January', 'February', 'March', 'April', 'May', 'June', 'October', 'November', 'December'] |
| Gymnocephalus cernua | Male | Main spermatogenesis activity | The peak of the spring wave of spermatogenesis, is observed annually under natural conditions, in late May, when all phases of spermatogenesis, from the reprodcution of spermatogonia to the formationof new ripe spermatozoids, are found in cysts of the testes. | ['April', 'May', 'June'] |
| Gymnocephalus cernua | Male | Maximum GSI value | In 3 test fish, the coefficient of maturity was 3.74, 4.18 and 4.80 | 3.0 percent |
| Gymnocephalus cernua | Male | Resting period | Periods in which gametogensis is absent occuring between spring and autumn [The coefficients of maturity after discharge of the spermatozoids (in the absence of spermatogensis) is on average 0.8% (range 0.5-1.2%), and after completion of the rearrangement of the somatic elements of the testes less than 0.25% | 7.0 months |