[Louis]

Let's say.....

1 : 1 = Current resolution (screen width) : Sachs' Standard
1 = Sach's Standard = 7 fishes

eg:
Current resolution is 1024x768 pixels
Sachs' Standard occupied 1024 pixels
( The width of coral's region = 1024 pixels and
the fish should be proportional to width of coral's region )

User Defined:
1 : 0.5
0.5 = User Defined = 7 / 0.5 = 14 fishes

eg:
Current resolution is 1024x768 pixels
Sachs' Standard occupied 1024*0.5 = 512 pixels
( The width of coral's region = 512 pixels and
the fish should be proportional to width of coral's region )

The tank would look bigger and more fishes could be put in.