have you asked yr health visitor or GP, they might be able to advise you, I totally understand why you need to know as have a friend with sea food allergic little one who even reacts through the skin if she picks up a crab on the beach, tongue swelling, going floppy,the works!! Also had allergic friend at uni who was allergic to fish oils in margerines. you need to make sure his first exposures are controlled and that you don't find out due to "accidental" contamination, though I think it is likely to be the second time when the allergy hits, because the first time is what primes the body to react (but don't quote me on that!)
also remember allergies can begin at any age,as you know from nephews case, my sister became seriously allergic to peanuts in her 20's, with absolutely no other family history of this
sorry not to be more help, but you are right to be concerned
Not sure if it helps but my DS is allergic to milk and the dietician advised me not to introduce him to fish until 12 months because its a common allergen. On that basis, you might want to wait until he's 12 months old before you try him.
I can see why you are worried but it is usually the tendency to be allergic that is inherited rather than a specific allergy.
Having said that I was allergic to fish as a child (and outgrew it, which is rare) and I will be waiting til 10 mo to try ds2 with fish (he is 7 mo now).
Ds1 is allergic to dairy and peanuts but not sesame, fish, eggs, tree nuts or any of the other usual food allergens out there, so trying to predict what a child may be allergic to is very hit and miss. Having said that tho, neither of my boys will be getting kiwi cause half my family is allergic to it.
A friend of mine was rushed to hospital suffering a life threatening reaction to eating tuna when he was about 30 years old after eating fish all his life. Don't know whether that's normal, or freakish though.
My son has has anaphylatic reaction to normal fish and been in the ambulance. The problem with allergies is that some people are just intolerant and some people are seriously allegic so when you say that you are allergic then people tend to assume intolerance except for peanuts where people assume that you are seriously allergic. We out to make the terminology clearer. All of my children have severe food allergies (not peanuts) so I always have to explain.