From the official website of Ben Chapman who played the water version of the Creature. The website can be located here
http://www.the-reelgillman.com/
Able to breathe surface air for only a few minutes before returning to a watery habitat
Is around 6 feet 5 inches in height on land and 5 feet 8 inches in the water! (due to actors of different height playing the creature)
Blood composition is approximately 35% white corpuscles, or "halfway between marine life and mammal." It is also important to note that these white corpuscles have no nucleus.
The Gillman falls in love with Kay (Julia Adams), the lone female in the party.
Outer layer of marine scales cover a layer of mammalian epidermis
Living primarily in the dark depths of the sea, the GillMan reacts adversely to bright light
Although it has been known to exhibit violent tendencies, such actions can be classified as defensive.
Typically, it usually hunts fish for its food.
The film was originally shot in 3-D