The thirty-fifth of Greater sins is consuming carrion, pork and blood and all those things on which Allah (S.w.T.)’s name has not been invoked during its slaughter as reported by Amash from Imam Ja’far as-Sadiq (a.s.) and Fazl ibn Shazān from Imam ‘Ali Riďa (a.s.). This fact is also mentioned in the Qur’an in Surah al-Baqarah Verse 173, Surah al-An’ām Verse 145 and Surah an-Nahl Verse 116.
In Surah al-Mā’ida Verse 3 Allah (S.w.T.) says,
“Forbidden to you is that which dies of itself, and blood, and flesh of swine, and that on which any other name than that of Allah has been invoked, and the strangled (animal) and that beaten to death, and that killed by a fall and that killed by being smitten with the horn, and that which wild beast have eaten, except what you slaughter, and what is sacrificed on stones set up (for idols) and that you divide by the arrows; that is a transgression.” (Surah al-Mā’ida 5:3)
Every animal that dies without the proper religious procedure is Carrion and eating of it is prohibited. If it has warm blood then it would also be Najis (ritually impure), but if it is properly slaughtered it is pure and clean (except dog and pig which will be always Najis and never considered clean and pure).
In a compilation of Anjuman al-Tablighāt Islami it is mentioned that Islamic Jurisprudence has specified and discussed in detail and prescribed the animals whose flesh is allowed. Only an expert in Life science could fully appreciate justification on which these laws are based.
Islam has prohibited the flesh of all carnivorous animals because there is dirt in the stomachs of such animals. The flesh is dirty and smelly and its consumption causes illness. On the other hand herbivorous animals are mostly considered permissible. Animals having claws are considered Harām and hoofed animals are mostly considered Halāl though some are considered as Makruh (unpleasant) such as Horse, Ass etc. Birds that flap their wings more and glide less while flying are Halāl and those who glide more and flap their wings less are Harām. Islam has also prescribed rules for hunting. Hunting is permissible for hunters who hunt to feed their family or for their sustenance. Hunting is not allowed for fun and entertainment. One who goes for hunting just for fun and play has to recite full prayers (it is not considered Qasr) he should also observe fast because this journey of his is unIslamic. (End of quotation from the compilation of Anjuman Tablighat al-Islami)
Animals are of Three types: Terrestrial, aquatic and flying. Terrestrial animals are of two kinds, domestic and wild.
Among the domestic animals only goats, sheep, cow and camel are Halāl, while flesh of horse, donkey and mule is detestable (Makruh), other than these six animals all domestic animals are Harām, like cat etc.
None of the wild animals are Halāl except deers and its kinds like the mountain goats, (12 horns), wild Cow, wild donkey and mule. Flesh of all carnivorous animals is Harām whether they are strong and powerful like lions, leopard and jackals etc. or weak like the fox; and in the same way the flesh of rabbit which is not from wild animals is also Harām.
Reptiles like snakes and rats etc., whether domesticated or wild. Insects and worms and porcupines and lice etc. are also Harām.
Birds like pigeon and all its kind are Halāl. For example, ringdove, partridge, wild duck, ducks and its kinds. Also birds and its kinds like Bulbul (nightingale), Chandol (name of a bird). Surad (bird with broad head with a peak half-black and half-white who hunts other birds). Swan (Greyish with long head, which mostly lives on a date tree) Shagrāq - Greenish beautiful bird similar to pigeon, it has a red, green and black lining on its black feather.
Bat, peacocks who have webbed feet or birds strong enough which can tear apart animal; or hunting birds, like Charkh (one kind of bird) Eagle, Shahīn, Bāshiq (which is also called as Bāhsā) or a weak bird like Vulture or crow and its kind should be avoided, also Zāgh (crow which inhabits cultivated soil, and Baga whose colour is black and white, those fat and black crows which eat Carrion; all such birds should not be used for food.
Whatever has been said is available in traditions in explicit terms. Regarding birds about where there is no express command these can be considered Halāl by applying the criteria mentioned in the beginning of the chapter: Birds that flap their wings more and glide less during flight are Halāl. Besides they should have Three additional characteristics: an additional finger below the thigh, crop (craw) and gizzard.
The egg of a bird has the same order as its flesh. The egg of a Halāl bird is Halāl and the egg of Harām bird is Harām. In order to determine whether an egg of unknown origin belongs to a Halāl bird or Harām we must see its shape. If one end is pointed and the other is rounded, like the egg of hen or pigeon, it is Halāl. If it is exactly round, or oval having the same shape at both ends it is to be considered Harām.
We should also remember that a permissible animal becomes Harām on account of two things:
1) By eating Najasat
2) By having been sexually assaulted by a man. The details of laws concerning the same are available in Tauzihul Masael and books of jurisprudence.
As regards aquatic animals, only those fishes are Halāl which have scales even though they might have fallen off, like the scales of Kan-at (a kind of fish) (Qoba fish). This is a very naughty fish and it bangs itself on everything and loses its scale and only the scales of its tail remain.