Michelle -
Yes definitely we always give the tuna can juice to the cat or cats. They do love it

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In terms of dry vs wet, I'm not sure I realized there was a difference. They both come in either oil or water, so that probably does make a difference. But, at least with the brands we get, both are just as "wet". I imagine different brands use different amounts of water / oil as "filler" - because that probably reduces their costs. I.e. I would think a better brand would be mostly fish, but a cheaper brand would be mostly water because that saves them money and the consumer still pays by the can.
I think the light tuna is mostly skipjack, from what I'm reading, but again that seems to be a brand-by-brand thing. I do love yellowtail so I wish they had type-percentages on the cans so I could see what is what. I wonder if they'll move in that direction as people become more aware of the differences.