Going to almost certainly be less than 1. Moving further up the food chain results in energy losses. Those fish are going to use energy for their own body and such
For sure, which is why I said "another food source would be needed." I had in mind something like the wild-caught fish being processed into something useful as part of a more efficient food chain, e.g. combined with efficiently-farmed plant material.
Moreover there’s high mortality rates inside of fish farms for fish themselves.
I don't have any context on the other pros and cons of fish farming, so definitely not arguing whether they're a net positive or not.