How can some cyprinodont fishes survive in stagnant water with little or no oxygen?

Some cyprinodont fishes are able to survive in stagnant or deoxygenated waters by utilizing the surface of the water for respiration. They achieve this either by taking in water at the surface film or by breaking the surface to gulp air.1

It is important to note that these fishes do not possess specialized accessory respiratory structures to perform this function. Instead, they rely on these behavioral adaptations to access oxygen in environments where it is otherwise scarce or absent.1