Hi there. I've just read the article and I have some pros and cons to it. I just want to share my experience on taking pictures of aquariums in different conditions. Here is a link to some of my pictures I have taken both of my aquarium and in public locations.
So, here are my guides:
1. Reflections: Reflections are always a problem, however reflections occur when there is more light outside the aquarium, rather than inside. Easiest way to fight reflections is to stay in the dark. So when you're taking pictures of your aqua turn off your ambient light and let the aquarium glow. Your camera will still be able to focus as there is enough light for it in the tank.
REMEMBER: Turn off your built-in flash unless you are reaaaaaallllly close to the glass and the reflection is not visible.
2. Aperture - using large aperture is tricky - if you use aperture 1.8 or 2.8 - you will have a reaally shallow depth of field (focus zone). This means that only some part of your fish will be focused. This will allow you however speeds around 1/80 to 1/160 depending on your tank light and ISO settings. So, if you're not using flash, you definitely depend on large aperture to get focused pictures without motion blur.
3. Flashing - sure you can use flash, however it must always be external. I am using flash all the time in my pics, it is positioned on one side of the aqua or sometimes I place it on top of it, replacing the aquarium lighting. Using an external flash is really rewarding - you can use smaller aperture (f8 - f16) and you are not slave to the speed. You can take as good pictures in 1/160 as well as 1/16 both on lowest ISO setting. The results are slightly different, but overall you don't get blurred shots.
WHY or HOW? - the fact is that the presence of light causes the blur, not the absence of it. It is hard to understand at first, but it is simple. Imagine the following - you have been in the club where there is this white, flashing strobe that blinks very fast, and it seems to you that you see dancing movements like stills - the persons in front of you just stop in a split second and on the next flash they've changed their postures. It is not that they're not moving in the darkness, it is just you don't see it.
The same happens with your camera - if you stay in a dark room, your camera is set to iso 100 aperture to 8 and your speed to 1/16, and you do not use a flash, you will hardly get anything else but a dark black picture. If there is an external flash above the aquarium, that flashes for just a split second - you will get all your fish frozen in that split second. Taking the same picture on speed 1/160 will produce merely the same result. The difference will be in the contrast of the picture and the dark zones - the pic on 1/160 should be darker in shadows, more contrasty. Of course flashing at 1/160 of a second puts more stress on your strobe, so your next shot will be delayed a bit. So, if you can get a remotely controlled flash unit above the tank - use it confidently, and remember ALWAYS avoid the built-in one.
4. Lens types - you are not limited to using MACRO or MICRO lens. Any kinds of lens are good as long as you know what you're doing. My latest pictures are shot with 50-150 mm lens from about 1.50 to 2 meters from the aquarium. Zoomed to the max (150mm) produces the so called 'close-up' photos. They are not macro shots, but you can see enough detail on the fish and scales. My older pics are made with my older lens 50mm 1.8 and 18-70 kit lens. Using longer lens to me was more rewarding than 'pressing' the camera next to the glass. WHY? Because it solves several problems - 1st fish do not get upset or nervous, 2nd I am avoiding reflections caused by the aquarium light, 3rd I have more control on the pic as I see more - using zoom lens I can focus on single fish and then fast get back and get a group shot.
5. Point and shoot cameras - to my opinion are pretty much incapable of taking adequate photos as they lack a lot of control.
So - yes, the article on Nikon page says the truth, but it does not show all the aspects of fish photography, neither all the options you have.