Fish gills because fish animals need to breathe and detoxify through fish gills, which contain many harmful microorganisms and dirty things, and the taste is very fishy, and the taste is not good, so eating may cause physical discomfort. 2. Toothed eels have sharp teeth and belong to a carnivorous animal. There may be a lot of dirty things left on their teeth, and there is no edible value. Therefore, the head of the seven-star eels is not suitable for eating.