It is described as being larger than a five-story building, a kilometer long (not including its tail) and sporting three rows of teeth in a mouth that can easily accommodate a train.

The Dogfish makes its first appearance in Chapter XXXIV when Pinocchio, recently transformed from a donkey to his puppet form, has entered the sea to escape from his former owner.

In the 1940 Walt Disney film Pinocchio, the Dogfish is named Monstro (which is Portuguese, Esperanto, and archaic Italian for "monster") and is portrayed as an aggressive and man-eating sperm whale, in contrast with the "gentle giants of the sea" in real life, with massive jaws, both of which have sharp teeth, and a grooved underside like a rorqual, similar to the whale in the novel Moby Dick.

Unfortunately, just as Geppetto feared, this serves only to infuriate him after drinking lots of water to put the fire out, and he pursues them, using surprise attacks in attempts to kill them, but fails.

Monstro makes a guest star appearance in a Bonkers comic story titled "Whale of a Tale", published in the December 1994 issue of Disney Adventures.

Monstro also appears in the video game Kingdom Hearts as both a supporting character and a world, where Pinocchio and Geppetto temporarily live inside him until being rescued.

Within him dwell many Heartless, including one called the Parasite Cage, which traps Pinocchio in its cage-like stomach, and delivers him to Riku, who wishes to use his heart to rescue Kairi.

Before he could reconsume them when he eventually catches up to them, Pinocchio propels the boat one last time and they zoom into a nearby tunnel for safety, but Monstro runs into the cliffs and ends up smashing against them on impact.