Mystery fish postcard

From: http://www.cryptomundo.com/cryptozoo-news/mysfishrev/

The Mystery Fish postcard, (first noted here (http://www.cryptomundo.com/cryptozoo-news/mysfishrev/) , CryptoMundo) on November 29, 2005, has never been identified, as to exact location or species. Several thousand new readers have found their way to Cryptomundo since November, so here’s a quick revisit to that photographic mystery.

The men in the picture look like military servicemen. The surroundings look like this photograph was taken on a beach or island. The fish appears to be about six feet long (notice the yard or meter stick lying next to it). But where are the fins on this cryptid (or even a tail)? What is it?

Note: There is nothing on the back of this postcard, except it should be noted that the "Place Stamp Here" box is formed by the letters AZO, which according to the comments below date this card. All the AZO triangles are pointing upward, thus indicating a date for this postcard of 1904-18. It was contributed by a reader (Ms. Phyllis Mancz of Ohio) of Loren’s Cryptozoo News blog at Cryptomundo.