Chinese sleeper (Amur sleeper) – Perccottus glenii

The Chinese sleeper, a species of the perciforms native to Asia, differs clearly in appearance and lifestyle from gobies native to Finland. Its habitats are mainly small waterways rich in submerged aquatic vegetation, such as shallow ponds, lakes and slow-moving streams. The Chinese sleeper is a voracious, omnivorous predator and can grow to approximately 25 cm in length and weigh 350 g.

It reaches sexual maturity when it is around 4 to 6 cm long and its life span may be 5 to 8 years. Chinese sleepers spawn in summer during several periods, when the surface water temperature is 15–20°C. The female lays its oval eggs on aquatic plants or other surfaces. The male guards and tends to both the eggs it has fertilised and its fry. The Chinese sleeper can survive in ponds that have frozen all the way to the bottom and it can tolerate nutrient-rich, oxygen-deprived conditions.