... up your Aquaria directory, go into your gfx folder, and locate the two files called 'aquarian' and 'aquarian_alt'. Switch the names. Now, if you're playing through again and want to read all the messages on various walls, stalagmites, biers, and statues, you don't need to take a screenshot, minimize, and translate letter by letter. It's just right there, on the wall! Also handy for first-timers who don't really care about spoilers, I guess.
Note that the letters will sometimes overlap a bit at the corners, since Aquarian is a round font, and English text is more rectangular. Also, since the English text letters are in yellow as opposed to the black of Aquarian text, words will tend to pop out at you a little more, visually. Personally, I think Alec and Derek used this method to plan the location and content of the various hints and notes during development.