- Order: Piscine Wyvern
- Suborder: Land Fish
- Family: Delex
Delex feed on rodents, insects, lizards, small birds, and weak or sick animals. These creatures are also notorious scavengers and clear the environment of any carcasses. However they're also low on the food chain and are preyed upon by Great Jaggi, Nibelsnarf, Rathian, Tigrex, Tigerstripe Zamtrios and Deviljho. They also feed off leftovers left behind by Jhen Mohran.
The average size of an adult Delex is approximately 405.8cm. Delex look very different compared to most other Piscine Wyverns. Their shape allows them to swim in the sand, like the Cephalos, and also "crawl" on land. The front limbs of Delex have evolved into fins while their back limbs have degenerated completely. They can't breath in the sand so they have to occasionally jump out the sand in order to breath air. While swimming, however, they will swallow some of the sand as they swim. The swallowed sand is stored in a special organ in their body, that combines sand with its mucus, and saves this sand as a weapon to injure prey.
Delex are rather calm until provoked by a threat. When provoked, Delex will either flee or attack the threat. One lone Delex is very weak alone but, in a group Delex can overpower larger prey. Though once at least one member of their group is killed, the Delex group will swim away from a threat as quickly as possible. Delex can be seen following Jhen Mohran and Dah'ren Mohran due to them wanting to feed on leftovers left behind by the giants. This is risky, however, since the giants may also swallow the Delex while feeding, leaving behind fins or other parts in their mouth.