 The eggs hatch after 13 days, into 7– to 11-mm-long hatchlings with a large yolk sac, minimal sight, minimal swimming ability, and a strong tendency to seek cover.After another 9–12 days, they mature to a swimming larval stage at about 15 mm in length, resembling a miniature adult by the time they reach 20 mm in length and begin feeding.They then drift downstream in the deep channels of the river, remaining in freshwater for the first year of their lives.