Didzioji g. 28 (in Old Town Vilinus)
Mobile Tel: +370.615.38498
http://www.rimi.lt (despite this being on the business card, the site appears to be for the supermarket downstairs; maybe they own the restaurant)
Aqua serves breakfast and lunch cafeteria-style. The decor is fairly upscale, and it attracts a matching local clientele. Foreigners look somewhat more scruffy, because while the prices are high by Lithuanian standards, they're certainly not by Western ones. My lunch came to Lt. 12.50 ($4.16) on my first visit (entree, side dish, vegetable, and soft drink), and Lt. 25 ($8.32) when I was really trying to spend all my remaining Lithuanian money. I couldn't finish it all, that time.
The food, as I said, is fine, if nothing spectacular. Lithuanian and international cafeteria food, although one highlight is that they have a nice free-standing salad bar. Service is friendly and polite. You'll probably need to ask someone what things are because they're labelled in Lithuanian, but many of the staff speak English.
Overall, an inexpensive, cheap, quick place to have breakfast or lunch in the Old Town. If you can cope with the 70's disco they've decided on for background music, you'll probably like it. Note that although they're open late, sometime around 2PM they convert from a cafeteria to an upscale bar.