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.Brian W. Coad Freshwater Fishes of Iran (accessed 18 Feb 2015)
It has been found at a depth of . The length of the fish was TL.
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