The lake is within the Tumba-Ngiri-Maindombe area, the largest Wetland of International Importance recognized by the Ramsar Convention in the world.

[2] Mai-Ndombe contains acidic, humic-rich blackwater and in general the fish of this lake have been poorly documented, even compared to other regions in the Congo River basin.

[2][3] Initial surveys were performed by George Albert Boulenger more than a century ago and there have been relatively few later studies of the fish fauna in the lake.

[2] The remaining are relatively recent discoveries that only were described in the last few decades: In 1984, a new species of cichlid, Nanochromis transvestitus, named for the fact that it exhibits reverse sexual dichromatism, was scientifically described from the lake.

[3] Some of the main concession areas of the logging company Sodefor are to the north and south of Lake Mai-Ndombe.