Marine Aquarium 3.1 can be downloaded from:
https://prolific.s3.amazonaws.com/Ma...eAquarium3.exe
If you have an MA3 Key on your computer, the program will simply recognize it. If you have an MA3 Key, but haven't typed it in yet, you can do so.
MA3.1 is a free upgrade for MA3, and a $9.95 upgrade for any previous version. Keys can be purchased at SereneScreen.com. If you had a Key and lost it, that can be researched by either the robot Lost Key function at SereneScreen.com or Customer Service.