Re: ADA Mini M-ish Journal
Looking forward to seeing what you do with it.
As for ISO for taking aquarium shots it doesn't really matter. Higher ISO is more sensitive to light which means you can have a faster shutter speed. The main downside there is that the higher ISO can also lead to increased colour noise in your images. I'd opt for supporting the camera and using a slower shutter speed, either with a tripod or if you don't have one a little table or even a stack of solid books.
If you use a slow shutter then use the timer to take the picture, as even the pressure from pressing the release button can cause some blur.
Hope that helps,
Rob