food poisoning

I bought two prepacked lightly smoked fresh snoek with a sell by date of the 24th and use by date of the 25th April. When I opened one to cook, I got a very fishy smell, which I thought OK it's fish, so yes a stronger smell than normal, probably caused by the packaging. The flesh was a bit sticky but I thought it just needed to be washed off. So i cleaned and cooked it but noticed that it had a very pungent taste which I had not experienced previously (had purchased this fish before). Today both hubby and I have food poisoning. I am upset with myself as I should have listened to my instincts and should've wrapped it up and returned it to the store BUT I am more disappointed in woolworths as a consumer. I shop with them because of their quality checks that they normally have in place and for something like this to happen is unforgiveable. I was so looking forward to having fish last night and at a per kg price of R109.99 I didnt't expect to get food poisoning from it. I am very shocked and will really reconsider buying fish from woolworths ever again. I have no doubt in my mind that the fish is spoilt and the sell by date is incorrect. Im taking the other snoek back. Disgusted