Navigate to the folder in which you installed Aquaria. (For a Steam install,
this is "C:\Program Files\Steam\steamapps\common\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.