Only some zoanthids release toxins and that's mostly when you cut them or frag them. Also if you boil live rock and there are zoanthids on them, it can be pretty bad! I read one story where a couple was hospitalized after the husband boiled liverock with zoanthids on them. The effects can be pretty bad in the worst cases. But mostly you will be fine. They say to wear gloves and eye protection when fragging zoas to keep from bring irritated by the toxins. This doesn't mean "stay away" from zoas, just means to be cautious.
Lion fish are also poisonous, as well as cowfish. This doesn't mean to not have them in your tanks, just means to be cautious once again!
20 Gallon Nano Reef