Legend have it, when the watch is bought brand new, one should give the watch a good lick. One taste like tuna, while the other more like sardine, hence the association of nickname.
Hahahahahahaha! If the watch tastes or smells like fish I doubt it's still new. Have you smelt old leather straps? Eeeeyew!!!
Glampyre, the nickname "tuna" was given when those Prospex divers were launched. They were one of the chunkiest watches around and reminded collectors of cans of tuna, hence the name. It was first used on some of the US forums and the name stuck.
The other watch was initially called a "baby tuna" and still is refered to as such. But others have called them "sardines" which also helps to differentiate them further; "sardine" seems more common nowadays especially after the blue sardine was recently launched. And "sardine" was used only cause it's a smaller fish (ergo, a smaller watch) AND it's another canned fish, even though a sardine can is sometimes bigger than a tuna can. But go figure.
Hope that helps explain things.
I'll try to take more pics this weekend, weather permitting. Got a few more watches to go... hehehehe
Not the latest shot... Hmmm needs to be updated too. Have already overfilled this case.