https://www.babycenter.com/408_when-can-my-baby-eat-fish_1368510.bc
this says you shouldnt give it until three preferably because its got a very high raking on the allergy list or something (couldnt be bothered to read it all).
I havent given Alex fish yet, but thats only because we dont buy fish or fish fingers, im not keen and OH hates it so we dont bother with it. But if we did like it, I probably would have tried him on little soft bits of cod or given him a fish finger to chew at about 8 months ish?
Im not really the best person to answer seeing as we dont eat it but i suppose you can read through the link, its got comments off people sayign what age they gave their babies fish xx