The diamond killifish (Fundulus xenicus) is a species of North American killifish found in salt marshes, hypersaline flats and mangrove along the Gulf Coast of the United States.

[1] This species grows to a length of 6 cm (2.4 in).

It is found in the aquarium trade.

Nucleotide analyses has reevaluated the phylogeny of the Funduliidae and placed the diamond killifish into the Fundulus genus.

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