Aphaniusisfahanensis is a new endemic killifish species that has been described in the Zayandeh River of the Isfahan basin in Iran. During a study on the biology of nine fish from this species, the parasite Diplostomumspathaceum was observed in the aqueous humor of the eye of a single individual. It was visible as a white mass with a diameter of 0.38 mm. This is the first report on the infectio...