Are crayfish considered a type of "hair food" (trigger food)?
Whether crayfish is considered a "trigger food" (fayu) depends on individual circumstances. If someone has an allergic constitution or suffers from skin conditions, crayfish can be regarded as a trigger food. However, for those without such issues, it is generally not considered a trigger food. Detailed analysis is as follows:

Trigger foods refer to those that are nutritionally rich or have stimulating properties, which may induce or exacerbate diseases. For individuals with allergic constitutions or skin disorders such as eczema or urticaria, crayfish may act as a trigger food. Its high protein content might provoke or worsen allergic reactions, including symptoms like skin itching and red patches.
However, for generally healthy individuals, moderate consumption of crayfish does not typically cause noticeable discomfort or disease flare-ups. Crayfish is rich in protein, minerals, and vitamins, and moderate intake can be beneficial to health. Therefore, in such cases, crayfish should not simply be categorized as a trigger food.
In daily diets, attention should be paid to food hygiene and cooking methods, avoiding excessive consumption of any single food item to ensure food safety.