Neostethus thessa, locally known as bolinao, is a species of freshwater priapium fish endemic to Lake Mainit, Mindanao, Philippines.

It is classified as Endangered by the IUCN Red List of Threatened Species due to its highly restricted range which is threatened by pollution and the introduction of invasive species of fish.

Like other priapium fish (and the origin of their common name), the males are distinguished by a muscular clasping organ from modified fins found under their "chin".

[1] Neostethus thessa is classified as Endangered by the IUCN Red List of Threatened Species.

It is also threatened by the introduction of invasive species of fish, including the Nile tilapia and the Eurasian carp.