Navigate to the folder in which you installed Aquaria. (For a Steam install, this is "C:Program FilesSteamsteamappscommon aquaria". If you have a 64-bit PC, replace "Program Files" with "Program Files (x86)". For the Mac version, right click on the Aquaria application and click "Show Package Contents".) In here there should be a folder called "gfx". Two of the files in this folder should be "aquarian.png" and "aquarian_alt.png". Swap the names of those two files. This should replace all of the symbols written on the wall with English text.