It is reported that the Prophet ﷺ said: "Two dead things and two bloods have been made permissible to us: fish and locusts, liver and spleen." Ibn al-Qayyim, for his part, says that there are several kinds of fish, and that the best is the one with good taste and a good smell, of medium size, with thin skin, and whose flesh is neither tough nor dry. It is also the one that lives in fresh water over a gravel bed, feeding on plants rather than refuse.
The best place for fish is a good watercourse leading to rocky then sandy spots, as well as running, sweet waters that are not fouled by refuse or mud, that are stirred, rippling, and exposed to the sun.
Sea fish is good, commendable, and mild if fresh, and is cold and moist. It is hard to digest and produces a great deal of phlegm. On the other hand, it produces a commendable humor, fertilizes the body, increases sperm levels, and improves the hot humors.
As for salted fish, the best is that which has been salted most recently; it is hot and dry.
The longer it is kept, the more its heat and dryness increase.
The eel is very slimy, and the Jews did not eat it in the time of Ibn al-Qayyim. If eaten fresh, it loosens the bowels; if salted and left to sit for a long time, it improves the windpipe and the voice. If crushed to make an external application, it helps to extract the placenta and the excess matter from the depths of the body, for it has a drawing action. He also says that the salted water of the eel is suitable for one with an intestinal lesion.
The fatty acids it contains, such as Omega 3s, are a healing for sciatica. The best part of the fish is the part near its tail, which is fresh and fatty, whether the flesh or the fat, and fertile for the body.
Jabir Ibn Abdallah reports that the Prophet ﷺ sent them out with three hundred horsemen, accompanied by their commander Abu Ubaydah Ibn al-Jarrah, and that when they reached the seashore, hungry, they ate the leaves that had fallen from the trees to the ground. Suddenly, the sea cast up a fish called "amber," and they ate it for fifteen days, using its fat as a seasoning, which allowed them to regain their strength.
