Blade-Tooth grants Moonfish the ability to enlarge and reshape his teeth into sharp blades.
The blades can vary in both size and shape. The user can manipulate the length and direction of the teeth at will. They are powerful enough to break through Shoto Todoroki's ice but can be shattered with enough force. 
Moonfish uses his Quirk to increase his mobility and attack his targets from a distance. The villain barrages his opponents with torrents of teeth attacks to overwhelm them and break down their defenses. The blades are fast and can stretch to incredible lengths, making them perfect for Moonfish to skewer his foes from afar.
Moonfish has experience using his Quirk and is capable of using it as an extra set of limbs. Despite being contained inside a straight jacket, Moonfish is a deadly foe because of his mastery over his Quirk. Moonfish can suspend himself in the air and even move by manipulating his teeth.