After getting food poisoning, I decided to google gindara aka escolar and was surprised to find its effect.
Gindara was the name that the Japanese restaurant used to call the fish. Escolar is its more scientific name.
What I found is that escolar is a type of snake mackerel that cannot metabolize the wax esters (gempylotoxin) naturally found in its diet. The gempylotoxin is very similar to mineral oil and gives the escolar an oil content of 14–25%. This is what gives the escolar its buttery texture.
Unfortunately, human beings are not meant to consume such high quantities of gempylotoxin and hence my adverse reactions (nausea, vomiting, etc). Basically, just imagine drinking mineral oil.
This apparently isn't new because both Italy and Japan banned the sale of the fish. Since 1977, the Japanese government considers escolar to be toxic. In 2007, Hong Kong recommended that escolar not be used for catering purposes. Apparently, the cooking method doesn't matter as the wax ester content remains the same.
In the United States, the FDA informally recommends, "Escolar should not be marketed in interstate commerce."
For countries like Singapore that don't regulate escolar, it would be best for consumers to eat it in moderation by limiting portions to six ounces (170 g) or less, consume portions close to the tail which typically have a lower wax ester content, or simply avoid it all together.
I have learned my lesson and hope that you won't have to suffer through it too.