so is this like the rat, cat, toxoplasmosis trio?

Basically. They swim closer to the surface of the water.

And that parasite that makes snail eye stalks go googly to attract birds to eat it…

"Brain-encysting" was not a word I ever wanted to learn

Is that a part of the worm's parasitic life-cycle, or is it just a thing that happens?

Nice, ok, so I was assuming:

1. Infected fish swim closer to the water to be eaten by birds
2. The flatworms reproduce in the bird; flatworm eggs are shed in bird waste
3. Fish eat the bird waste and get infected

I remember that for toxoplasmosis, they could only reproduce inside cats