Delex are small Piscine Wyverns that are fish-like in appearance, sporting long dorsal fins and reptilian-like snouts lined with sharp teeth. They have, like the Cephalos, the ability to "swim" through sand and even expel small sand blasts from their mouth at attackers. These blasts may occasionally inflict Waterblight.
Due to their nimbleness they are difficult to hit with slower weapons. Several appear in the fight with Jhen Mohran, jumping onto the boat and attacking Hunters that get in their way. Delex hunt in small groups of six or seven individuals and likely prey upon small animals. They also scavenge off the remains left by larger desert-dwelling monsters, such as Jhen Mohran.
- Delex is the only Piscine Wyvern featured in Monster Hunter 3 and Monster Hunter Portable 3rd.
- The Delex is the smallest known Piscine Wyvern in the entire Monster Hunter series.
- A small noise, like a bell, can emitted by one of the group (usually after an individual has died) to instruct the rest of the group to flee the area.
- Sensitive to sound, the use of a Sonic Bomb will send Delex launching out from the sand, making them vulnerable to attacks for a few seconds. Large monsters' roars such as Diablos can also cause this effect.