- Order: Ichthyosauria
- Suborder: Fish Feet Wyvern
- Superfamily: Lava Wyvern
- Family: Lavasioth
Being a Piscine Wyvern, Lavasioth is related to Plesioth and Cephadrome, though it is more closely related to Lavasioth Subspecies. Goruganosu and Aruganosu are said to be the Supremacy Species of Lavasioth.
Lavasioth is found only in the Old World Volcano.
Lavasioth is high up the Volcano food-chain. It is fond of Apceros and Ceanataur, both of which it can catch by burning through the rock below them, catching them by surprise. However these creatures must compete with other predators such as Rathalos, Teostra, Lunastra, Rajang, Brachydios, Agnaktor and Akantor, all of which can be deadly competitors to the Piscine Wyvern.
Lavasioth are very well adapted to live in their habitat. Having a layer of hardened lava, coal, and ore on its skin makes it very durable. They also have the ability to spit lava, which is used to attack prey, or any other monsters that may pose a threat. The Lavasioth has been known to kill Vespoids, which may sting Lavasioth causing them to be irritated. The eyesight of these creatures is quite poor as is common among Piscine Wyverns. Despite the bad eyesight, the Lavasioth's other senses are quite good. Lavasioth are powerful swimmers in lava and their speed in swimming through the volcanic rock is matched only by the magma-dwelling Leviathan known as Agnaktor. During the mating season, female Lavasioth will cover themselves in rare volcanic ores in order to attract a mate, giving them a reddish-crimson color.
Some unusual individuals have reddish tinted skin, clean white teeth and use new techniques for attacking. These individuals also perform an unusual mad hopping behavior once thought to mainly be used by Bird Wyverns such as when a Yian Kut-ku goes into Rage Mode. This mad hopping usually smashes intruders beneath its feet. They have also been seen spitting lava chunks into the air around them to let them rain on surrounding intruders.
Lavasioth are extremely territorial and will attack any monster or human that enters its area with ferocity, excluding one of its own kind.