I have heard that prawns are makrooh. Is this true?
According to the reaserch of the Shafi’ee, Maliki, and hanbali school of thought, they are halal because these three imams say that all sea animals are halal.
However, within the hanafi school of fiqh there are two opinions regarding prawns. Imam Abu Hanifah rahmatullahi alayhi says that among the creatures that live in water, only fish is halal. This is due to the Hadeeth which uses the word سمك samak ie. Fish.
Now there is a debate within the Hanafi school as to whether prawns can be classed as fish or not.
According to many linguistic specialists prawns are a type of fish, as stated in the ‘Qamoos’ and ‘Taajul Uroos’.
Also, Allama Dameeri has written in his book ‘Hayyatul Hayawaan’
الروبيان هو سمك صغير جدا أحمر
Translation: “Prawns are very small red fish”
On this basis, many of the Hanafi Scholars have said prawns are halal.
However the modern day animal classification experts do not count prawns as a type of fish. They say the definition of fish is:
هو حيوان ذو عمود فقري يعيش في الماء و يسبح بعواماته و يتنفس بغلصمته
Translation: A fish is that creature which has a backbone, lives in water, swims with its fins and breathes through its gills.
Prawns do not come under the category of fish, because they do not have a backbone nor do they breathe through gills. So they fall under the category of insects, and would not be allowed.
Since many Ulama still regard prawns as a fish and eating them is common amongst them so eating prawns cannot be classed as haram.
However, due to the conflicting evidence, they could be classed as Makrooh. It would be better to avoid them. But, if someone does eat them, we shouldn’t say anything to them. Allah knows best.
( from Fiqhi Maqaalat- Mufti Taqi Saheb pg. 217 vol.3)