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.
Carnivorous monsters that inhabit deserts. Delex always travel in schools of five or six. When near large monsters on a hunt, they attempt to surround the prey and scavenge food. Known to flee if other Delex are injured.
Carnivorous desert monsters that often travel in schools of four or five. When near large monsters on the hunt, they will attempt to surround the prey and scavenge feed. Their aural sensitivity makes them weak against Sonic Bombs.
The Delex is the smallest known Piscine Wyvern in the entire Monster Hunter series.
A small noise, like a bell, can be emitted by one of the group (usually after an individual has died) to instruct the rest of the group to flee the area.
They will also make this noise when forced out of the sand.
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.
Delex's movement speed is almost par with most charge attacks of monsters.
Delex is the only Piscine Wyvern featured in Monster Hunter 3 and Monster Hunter Portable 3rd.
In Areas 9 and 10 of the Sandy Plains, after a few minutes of being in the same area as a hunter, Delex will swim toward the opposite area and disappear from the current area, but spawn in the other area they swam toward.
Delex was the only Piscine Wyvern featured in MH4 and it is only found in the Great Desert in MH4 and is now also found in the Dunes in MH4U.