Answer
(Fatwa: 33/33/M=1433)
According to Hanafi Fiqh, all the species of fish are halal provided they are samak (fulfil the definition of fish). There is difference whether lobster is fish or not. It is makrooh to eat lobster according to those who consider it out of the species of fish. If someone eats it then it is not unlawful but it is better to avoid. Apart from lobster, whatever sea food you wrote we are not aware of them. However, if it is learnt by study that its consumption is unlawful then also it does not imply that its business is also unlawful. It is lawful to sell and purchase them for external use.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband