We oftentimes will freeze our fish in ziploc bags full of water. I have very little problems with leaks. I would say about one bag out of every 3 boxes I buy will leak. Are you getting the ones made for the freezer or just the general purpose?
We do the same with fish. Try this, after filling and zipping the bags closed, stand them up in a plastic container of some type (we use a large rectangular shaped tupperware container that holds 5-6 bags side by side). Make sure the zip area is pointed up. After they freezer remove them from the container and store in whatever direction you like.
Works well for us and we freezer fish, dove, wild turkey, quail....etc all this way