system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do the populations of poisonous animals (lionfish, poison dart frogs, etc) not run rampant with no natural predators to corral them?
gpt
Both of those animals do have natural predators.

Lionfish:

>adult lionfish have few identified natural predators, likely from the effectiveness of their venomous spines. Moray eels (family Muraenidae),[13] bluespotted cornetfish (Fistularia commersonii), and large groupers, like the tiger grouper (Mycteroperca tigris)[14] and Nassau grouper (Epinephelus striatus), have been observed preying on lionfish.[15][16][17][18] It remains unknown, however, how commonly these predators prey on lionfish.[19] Sharks are also believed to be capable of preying on lionfish with no ill effects from their spines.


Poison dart frogs:

>Despite the toxins used by some poison dart frogs, some predators have developed the ability to withstand them. One is the snake Leimadophis epinephelus, which has developed immunity to the poison


Besides, even with few predators they would be limited by their prey. If there isn't enough food, the populations of these animals will eventually plateau and decline.