[2][3] It was formerly known as Gerris najas, but the subgenus Aquarius was elevated to generic rank in 1990 on the basis of phylogenetic analysis.

[4][5] This species generally require moving waters, living in places like the stony margins of rivers.

[6] Aquarius najas is among the largest species of water striders, as typical of members of the genus Aquarius (including another European species, the on average marginally smaller A. paludum).

Adult females of A. najas average 16.5 mm (0.65 in) long and males about 30% smaller.

At night, they separate, and the females lay their eggs beneath the water in closely packed patches.