Sometimes grouper is “Lor Gor”, super hard to chew!
This is the commonly known lorgor, or rubberfish texture. and upon cooking it curls up like banana, and skin as hard as rhino horn, meat is hard like dried cardboard.
from our experience, this usually happens to coral fish (grouper) and snappers, and never happen with pelagic fish (mackerel, trevally, tuna). According to fisherman it’s because the fish muscle contracts too hard upon catch and never regain its natural form, but its totally safe to consume. How do we actually eat them? at least my grandma did something to the fish that up till now we still do. After frying, pull off the skin, and cut into thin slices or shreds, and cook Teowchew porridge!