3X optical zoom with basic elements (as in no ED or APO), macro focus range is only 2". Of course it is Canon, but it's fairly basic. And quite frankly, you can place two photo's side by side of the same subject, one composed through the view finder, one composed through the LCD, and chances are, the one composed through the view finder is going to be better.
I actually get a kick out watching people using the LCDs to compose their shot's. The subject moves and they try to coordinate their tracking with it and end up with half the subject, not a problem when it's a stationary subject I suppose, but in my opinion, the best results always come from the view finder. You'll generally notice things in the view finder that get ignored through the LCD.
For $309, you can get a lot more camera features you may not even know you want or need until you find yourself without them.
I would recommend the Canon 1S IS if that's the brand you want. It's a bit more, but the zoom is great, although minum focus is a bit sad, but the image stabilization system would be a huge plus in aquarium photography allowing for handheld shots in low light. Thelens is also fairly fast with an aperature of 3.1 at full zoom.
Price a zoom lens in that range and speed eh.
Of course the trade off is a lower resolution (most likely not a problem really, a 3.2 will give you a very good 8 X 10 in a digital printer) and is more than sufficient for any online application.