[Jeremy]

For those who may be having the same problem:

With my PC resolution set at 1920X1080, in Windows 7, Goldfish Aquarium 2 displayed perfectly. However, with the same setting, in Windows 10 and 11, it looked zoomed-in and failed to show a good part of the aquarium on all four sides (see 1.jpg). To get it to display full screen, as it previously did, in the "Goldfish Aquarium 2" settings I had to set "Windows Resolution and color bit" to 1024X768X32 (see 2.jpg), while my PC resolution remains at 1920X1080.
Now the entire aquarium displays and fills the whole screen (see 3.jpg).