I'd be very careful about giving that small a kitten all fish or all chicken. You don't want them becoming dependant on just that. Perhaps just soaking their kibble in some chicken broth or the juice from a tin of salmon or tuna. And remember that cats digestive systems can't handle milk properly. They might get a bout of diahrrea, and kittens with diahrrea area at a risk. Clean,fresh water after they are weaned is all they need for fluids. Here's a pretty good link for you to check out...
And by all means phone the Humane Society where you got your kittens or your Vet if you have any questions or problems you can't resolve yourself. The Humane Societys' moral and ethical involvement does'nt stop once the kittens are no longer in their residence.