No, I don't think it is guaranteed. If the fish has been frozen and defrosted then prepared I think that reduces the likelihood.
Mercury poisoning is another consederation !
MrsO had Ciguatera from eating reef fish, she was in a bad way and symptoms of one sort or another continued for months. Especially the neurological ones. We don't eat reef fish anymore (never eat Barracuda !)
http://en.wikipedia.org/wiki/Ciguatera