At the bottom of a sea, the Blob Fish basically remains stationary throughout its life. They rarely move unless food is found nearby, otherwise they will wait for prey to come close. Studies show the Blob Fish’ diet consists mainly of urchins, mollusks, crabs, lobsters, and other slow-moving ocean bottom feeders. When something edible comes by, the Blob Fish waits for it to come close. Even though Blob Fish literally have to muscle, they are still able to open and close their mouth. It is currently unknown of how much they eat in an amount of time. A Blob Fish barely moves at all when feeding. Where prey is scarce, some Blob Fish will die simply of starvation.
The Blob Fish is a predator, as it eats and doesn't get eaten by other animals. The Blob Fish has no natural predators, but they are commonly swept up off the ocean floor by human fishermen. So technically Blob Fish fall prey to humans.