More information for anyone who is still experiencing crashes (hopefully not many of you!):
Q: Why is Aquaria crashing on my first-generation iPad (iPad 1)?
A: The most likely cause is that you have too many apps on your iPad.
In addition to storage memory for apps, photos and other data (16, 32, or 64 GB), iPads have system memory which is used by iOS to manage the iPad's data, and by apps themselves (like Aquaria) when they're running. iOS needs a small amount of system memory to keep track of each app that's installed, in addition to the storage memory used by the app. If you only have a few apps installed, this will be just a trivial amount, but as you install more and more apps, iOS begins to use up so much system memory that there's not enough left for the apps to actually run. This is what causes Aquaria to crash.
Q: But it worked an hour ago / yesterday / last week, and I haven't installed anything since then!
A: iOS is complex, and the amount of system memory it uses can change over time for many reasons — the number of installed apps is just one factor. Things like syncing your iPad, checking mail, even just unlocking the screen can reduce the amount of memory available. If you're very close to the limit, you may find that Aquaria works fine on some days but not on others.
Q: Why does this only happen with Aquaria and not other apps?
A: This can happen with any app, and in fact can even happen to the Home screen itself if your iPad is too full. Aquaria is simply much bigger than most current iPad apps, so it runs into this problem sooner.
Q: What can I do to fix the problem?
A: First, upgrade Aquaria to version 1.0.2 or later. Version 1.0.2 includes an adjustment to graphics resolution for the iPad 1 (iPad 2 is unaffected) which will allow it to run more stably even when iOS is using a lot of memory. The change is tuned so you shouldn't notice any difference during normal gameplay.
Also make sure you're using the latest version of iOS; if not, updating iOS may solve your problem.
If that doesn't help, try deleting all the apps you're not actively using from your iPad — remember that you can always reinstall them from iTunes later. It may also help to restart your iPad (power it off and then turn it back on) right before playing Aquaria, which will clear out the system memory and make as much as possible available to the game.