Poisonous Fish

POISON, from POTION, a drink, later, a potion/poisonous drink, from Latin potare, "to drink."

I always thought that the French word for fish, poisson, looked just a bit too much like "poison," and that this was unfortunate. But that's just a coincidence. It's actually cognate to fish/piscis, where we get the zodiac sign Pisces and the Spanish get their pez/pescado. And the pescatarians get their pescatarian diet.

There are of course quite a lot of poisonous fish out there. You must be careful.