your baby is 2.5months, and may be by now 3months..he is sufferng from infant colic...

i expect him to outgrow this sensitivity,by say 6months or m fine, even if he outgrows by the time, he is ready to eat fish ! which is by 9months..
also, if at all your baby was allergic to fish or ne sea foods,,thn by now he would have rashes, skin eczma or ne other irritation,itchng,,or would have vomttd badly...
allergy is not sensitivity,,its abnormal hyper sensitivity !!!
let me add that right now he is sensitive to sea foods, which means that until his digestive system gets mature enough to digest meats(by 8months),,i expect him to outgrow his sensitivty...if not,,he might show his actual responses which might be ne allergic reaction,,just in a day or 48hours of intake of these foods...
this is not food allergy as of now,,by in future,,if it continues,,or aggrevates,,could be a sign tht your child is sensitive to sea foods...
wait until 8-9months, dont rule out the line that your child is sufferng from colic because he is allergic.,,
allergy is an abnormally high sensitivity to certain foods or substances,,while colic is persistent, unexplained crying in healthy baby between 2 weeks to 5-6months of age..allergy or asthma can be said as disease but colic is not a disease !!!!! its something that happens to almost all 70% babies,,and mostly they recover by the time they are ready for solids or by 1 year even !!!

check my other post of allergies and colic so that you understand the differnce between both and dont confuse them :

about allergy/food allergy/avoid allergy attacks :

http://www.indiaparenting.com/boards/showmessage.cgi?messageid=1747&table_name=dis_healthissues

http://www.indiaparenting.com/boards/showmessage.cgi?messageid=1742&table_name=dis_healthissues

http://www.indiaparenting.com/boards/showmessage.cgi?messageid=1744&table_name=dis_healthissues

http://www.indiaparenting.com/boards/showmessage.cgi?messageid=2002&table_name=dis_healthissues

http://www.indiaparenting.com/boards/showmessage.cgi?messageid=1980&table_name=dis_healthissues

about Colic/reflux/spitting :
http://www.indiaparenting.com/boards/showmessage.cgi?messageid=6873&table_name=dis_feeding

hope this suffcs.
Good Luck ! Neha replied. Thank you Hetal.
we were really worried that my baby allergic to fish.your reply was quite clear & well explained.I appreciate your efforts.
Thanks for all the support & guidance.
Regards,
Neha