Goldfish

In water it paddles back and forth, reversing every time it bumps a wall. Start a rainstorm and it climbs out and walks around on dry land, and it keeps walking after the weather clears unless it finds water again. Walkers head for the edge of the screen and despawn once they get there, so net the ones you want before the storm rather than during it. Depth does not matter either: fish down in the caverns or the underworld switch to walking when it rains on the surface.

A sloped block is all it takes. Slopes let them swim upward, and if the slope carries on past the waterline they will ride it straight out of the pool and start flopping on the floor. If you are building a decorative pond, keep the walls flat and vertical.

Any Bug Net picks one up to release later, or you can turn it into a Fish Bowl, which is both the display piece and by a wide margin the better thing to hand a merchant. Once bowled it cannot be released again unless you shimmer the furniture back apart. Fish produced by a Fish Statue cannot be netted at all and puff into smoke if you try, so a statue rig gives you kills and banner progress rather than stock to sell. During rain those statue fish come out as walkers, which do not count against the statue's spawn cap.

• A Blood Moon flips loose goldfish into Corrupt or Vicious versions by itself, worth remembering if your pond is inside the base.
• Vile and Vicious Powder do the same conversion on demand, though neither works on one that is currently walking around in the rain.
• The Gold Goldfish is a rare stand in for the ordinary one and the only version worth stopping for.

• It used to drop itself as a weak healing food, which is why the tooltip still reads like snack packaging. The line is a nod to the cracker brand.
• Goldfish, bunnies, birds and penguins are the only critters with banners of their own.
• Walkers spin as they fall, easiest to see if you release a handful up in space during a storm.
• A goldfish shaped cloud drifts past in the background now and then.