Mesogobius nigronotatus is a species of gobiid fish native to the Caspian Sea.

It is only known from a couple of samples, from Kazakhstan and the southern part of the sea; the type material has been lost.

It is suspected to be the same taxon as that known as Mesogobius nonultimus.

[1] It has been found at a depth of 43 metres (141 ft).

The length of the fish was 6 centimetres (2.4 in) TL.