Tetrodotoxin, found in puffer fish, inhibits sodium channels. This prevents depolarization of cardiac muscle and neurons, which leads to death if consumed in high enough quantity. The symptoms are vague (nausea, diarrhea, paresthesia), so questions will need to give some form of history about eating at a Japanese restaurant or eating pufferfish to give you a big hint. There is unfortunately not treatment.

The main ingested seafood toxins we should know (246 Fa2019)

Histamine, Tetrodotoxin, and Ciguatoxin. Histamine - spoiled dark meat (tuna, mahi mahi) causes like an anaphylactic reaction because the bacterial toxin converts histidine --> histamine. Tetrodoxin - seen in this Q, pufferfish - blocks Na channels NO depolarization Ciguatoxin - reef fish barracuda - opens Na channels so CONTINUAL depolarization

For last 2 no cure, supportive only