Wandering Eye Fish

This one does not wander in. It appears only while a Blood Moon is running and only when you are fishing: the bobber dips, you reel, and instead of a catch the game drops an enemy into the water a few tiles from the float. Nothing else triggers it, so a Blood Moon spent indoors will never produce one. A Chum Caster raises how often the reel turns up an enemy rather than a fish, and a Sonar Potion tells you which it will be before you commit. A Lifeform Analyzer also picks it out, since the game counts it among the rare spawns, and it takes only half the usual kill count to fill in the bestiary slot and unlock the banner.

Its top speed will run down a character in early gear across open ground, and that is what kills people. Its turning is nowhere near as good. Give yourself any movement accessory, a Cloud in a Bottle or a set of Rocket Boots will do, and start cutting tight circles around it. It commits to a heading, overshoots, and has to haul itself all the way back while you keep landing hits. Knockback will not help you open that gap either, since it does not flinch at all, so every bit of space you get has to come from your own movement.

It arrives beside your bobber with no warning and it is already at speed. In a small fishing hut that means it is on top of you before the rod is away, with no room to open a gap and a doorway between you and anywhere useful. Fish somewhere open, or at least somewhere with a clear exit line behind you. It will also follow you into the water, which most flying enemies cannot do, though it slows down while submerged, and that is a real advantage if you can bait it under.

• A Slimy Saddle stomp is the early game answer. Bounce on it once and it locks onto you vertically, then grinds its own health away ramming the underside of the mount. Watch what is below you between bounces.
• Confusion makes it drift off instead of chasing, and it will often wander far enough to despawn. That saves you, but it also costs you the drops, so it is an escape rather than a tactic.