A fish that can attach itself to other fish and suck their blood or body fluids.
Suckfish can make people think of scary things in the water, like monsters.
Examples:
The suckfish attached itself to the big fish.
I saw a suckfish in the water.
The suckfish is very small and has sharp teeth.
The suckfish is like a vampire of the sea!
The suckfish can suck all the blood from a big fish!
The suckfish is the scariest fish in the sea.