So, I'll admit : the Aquarium idea posted as a joke got me thinking "Hey, I could get a second turtle !?"
As soon as I read about the Aquarium, I actually purchased about 30 stacks of Stranglekelp, and stored them in my guild bank. It took me five days to finally realize there was no such thing as an Aquarium.
But, to the point : you CAN catch a second Sea Turtle, the same way you CAN catch a second Sewer Rat =)
For bragging rights, fish on!