I'm pretty sure this is not the case.

I've seen clams "in their own juice" and salmon "in broth", but I believe fish "in water" is purified and then added to the cooked fish, in most cases. Similarly to olive oil which fish may be canned with, but not cooked in.

Some of it is, and some of it isn't. There are several fish brands that advertise their tuna as packaged in "natural spring water." I believe the big ones (i.e. bumble bee, starkist, etc) do this. Then there are some, like Wild Planet, where they are canning only tuna meat and the water is a broth that leaks out of the fish and you're right, it is analogous to bone broth. Either way, if the can is BPA-free I'm sure the water is chock full of nutrients and is fine to consume.

Most "bone broth" is cooked very long and slow. The long slow cooking process leaches nutrients out from the bones as well as from connective tissues, cartilage, etc. I don't think cooking liquid is enough. Real nutrient dense broths cook for up to or more than 24 hours.

I think most of the water canned fish comes in is probably closer to "salted water" than a traditional bone broth. Of course, you still want to EAT the bones for sure, but as for sucking down all the water? Not so sure. I think you probably get more of the EFAs that may have leached out into the water but not so much on the minerals from the bones. (With canned salmon and sardines, you can see the water looks a little fatty.)

One thing I do want to point out is to read your labels. Most of the more expensive, genuinely wild-caught seafood in cans is packed in just water and salt, but most of the commercial brands are packed in "vegetable broth," and that usually means SOY. (If you read the label on Bumble Bee and Chicken of the Sea, for example, most of them say "Contains soy.") Very obnoxious how they sneak it into everything.

In the case of canned fish, the bones are usually so softened that you can simply eat them or stir them into whatever you're making with the fish and barely notice them. Eating the whole bones must provide even more full of the goodies from bones than whatever leaches out in the canning liquid.

A previous response noted Wild Planet, which doesn't even add water to most of their tuna. This is a brand I'm really starting to prefer. The fact that the tuna is cooked in the can during the process that preserves it, rather than being pre-cooked, then cooked again during preservation, really does seem to result in much better flavor and texture. Open one of these cans, and you find barely any liquid--and you don't even need to drain it.

But the tuna doesn't have bones, so I doubt the little liquid there is has much to offer, and Wild Planet seems not to make any claims about BPA-free cans--except for the sardines, whose BPA-free status Wild Planet is careful to mention on their website. AND, sardines do have bones that you can/should eat.

So once again, the diminutive but mighty canned sardine seems to rule.

UPDATE: Thanks to a comment below, I re-checked the website and found that Wild Planet indeed uses BPA-free cans. Sorry about that!

Before I went Paleo, and starting making home made bone broth, I was usually grossed out by what I used to call: Gefilte slime (the gelatinous stuff in a jar of Gefilte fish):

http://en.wikipedia.org/wiki/Gefilte_fish

Now that I'm more schooled on bone broth, that actually seems like broth (because it gels).

Right?

Mike

You have to look at the ingredients. I have yet to find a brand of "tuna packed in water" in our town that doesn't list "vegetable broth" and "soy" in it's ingredients. BTW, I was checking the ingredients in various flavoured tea bags at the store the other day to make sure it didn't contain artificial colors/flavors, and was surprised to find that most all of them contain soy (it hadn't dawned on me that I would need to look for soy). But an even a bigger shock was that more than a few of them listed fish in the ingredients! Now why on earth would tea need to contain either soy or fish??

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