The Ulama have differed with regards to the permissibility of prawns. The difference is based on whether prawns are part of the fish family or not. (Shaami Vol. 6 Pg. 306). Ulama such as Hazrat Maulana Ashraf Ali Thaanwi Rahimahullah and Hazrat Mufti Abdur Raheem Lajpuri Rahimahullah where of the opinion that prawns are fish whilst Hazrat Maulana Rasheed Ahmed Gangohi Rahimahullah, Hazrat Maulana Khaleel Ahmed Saharanpuri Rahimahullah and Hazrat Maulana Rasheed Ahmed Ludyanwi Rahimahullah believed they are not fish.

Those that classify it as not being from the fish family base it upon the categorization of science and oceanology.

Hazrat Mufti Rasheed Ahmed Ludyanwi Rahimahullah in Ahsanul Fatāwā mentions that there are three features that are distinguishing factors of a fish.

1) The Spine 2) Gills 3) Fins

These features are not found in prawns; hence prawns are not fish.

On the other hand, those that classify it as a fish use the Arabic definition of prawns as well as acceptable social norms (Urf). Hazrat Mufti Abdur Raheem Lajpuri  classified prawns as a fish as they have been referred to as “fish”. Hereunder are some references;

Hazrat Mufti Mahmood Sahib Rahimahullah after mentioning both opinions shows inclination towards the group that advocates abstention and says “the mere fact of dispute relating to its consumption dictates that one should refrain from its intake hence the hadith دع ما يريبك إلى ما لايريبك (‘Leave that which places you in doubt for that which wherein there is no doubt’) also demands its preclusion”. (Fataawa Mahmudiyah Vol. 5 Pg. 123) 

For more information we recommend you to refer to Hadrat Mufti Taqi Saheb’s Risaala which sheds light on this topic. The Risaala can be found in his book tiltled “Fiqhi Maqaalaat” (VOL 3 Pg.216 Memon Islaamic Publishers )

Concerning your Question whether it will be correct to classify prawns as Haraam.

For those Ulama that have Yaqeen that Prawns are not fish, for them Prawns will be Haraam and it will be correct for them to classify it as Haraam. For Those Ulama that believe Prawns to be a Fish then for them it will be Halaal and they will classify it as such.

AND ALLAH TA'AALA ALONE IN HIS INFINITE KNOWLEDGE KNOWS BEST

ANSWERED BY: Ebrahim Patel 

CHECKED AND APPROVED BY: Mufti Muhammed Saeed Motara Saheb D.B. 

Islamic Date: 13 Rabi'ul Awwal 1440 - English Date: 21 November 2018