The Abyssal Angler is a Hardmodeenemy found rarely in the Aquatic Depths. It swims towards the player whether or not they are submerged in water to deal contact damage and inflict the Feral Bitedebuff. It becomes less visible, in a manner similar to stealth, the farther away it is from the player, reaching minimum visibility at about 18 tiles away. However, the gold coin acting as its lure always has the same visibility and glows slightly.
In real life angler fish will try to lure other fish in by producing light from their modified spine. The Abyssal Angler will similarly try to lure players in with a Gold Coin.