Instant Eels are a species of animals from The Magic Tree Of Nowhere. Courage tries to protect the tree from Eustace (who wanted to cut the tree down). Courage uses the bulldozer the tree gave him to dig a moat with a small island surrounding the tree, and makes a massive sandcastle fortress to protect it. Courage takes a bag that says "Instant Eel" and he pours it out of the bag and into the water. A massive green Eel emerges and roars at Courage, before pausing to sing.
Eustace charges, but Courage throws marbles at him and Eustace slips and falls into the water and the Instant Eel bites Eustace and Eustace jumps out of the water screaming. Eustace ties a handkerchief around a huge boulder and swings it high which causes Eustace to fly until he will reach the island. Courage uses a huge baseball bat, but Courage knows that Eustace is gonna miss. Eustace crashes into the wall of the sand castle and falls into the moat again and the Eel attacks Eustace again.
A lot of battles weren't shown. Eustace gets on a catapult and cuts the rope and says "Chop chop chop chop!," but he falls into Courage's boiling stew and falls back into the moat. Both Eustace and the eel then rise out of the water and start singing together for a brief moment until the eel grabs Eustace and shakes the farmer in his jaws.
After this, both the eel and the sandcastle doesn't appear again, it's unknown what happened to that eel, but surely he has survived.
They are giant eels with a really long body, which is covered by dark green scales. They have also big jaws with sharp teeth, and barbs under the mouth. On the spine, they have the typical dorsal fin of eels which runs the entire upper part of the body from the neck to the tail. Being serpentine-like, they have no hind legs but only two thin arms near the head. Their eyes are mighty and menacing.
They are really loyal and affidable creatures. Once "summoned", they will defend the area (or building) the summoner ordered them to defend to death. Everyone who wants to attack that area will have lot of problems facing these powerful sea serpents, as they are ferocious powerful predators with an insatiable bloodlust.
The eels summoned by Courage loved to sing, and he was as well really murderous as well his species is.
- The song the Eel sings is a ballad called Danny Boy, a message not only from a parent to a child who is leaving for war but also used on Irish funerals.
- Even if they are called "eels" they are more similar than a typical mythological sea serpent which is a reptile and not a fish.