Kate, the little red fish is a male Cherry Barb, and the little orange ones - with black stripes along their bodies - are female Cherry Barbs. That's why I love Cherry Barbs so much - they're such beautiful small fish

The males are a stunning deep red color! Very impressive especially when breeding.
Lilsoccakid, Ninja is right - I am using a digital single lens camera, Nikon D40. I guess this is the most basic one of the Nikon lens cameras. Great for beginners such as myself. The lens is interchangeable, as Ninja said, which means you can attach different length lens to your existing camera, without the need to buy a new camera if you want new lens. My lens is 18-55 mm. It's so-so in terms of the distance you can zoom in. But good enough for me right now. In the future I want to buy 2 lenses: one for landscape shots (wide-angle lens), and one for micro-photography (narrow-angle lens). I'd especially love some extreme narrow-angle lens because this would allow me to take great shots of extremely small objects, ex. detailed close-up of leaves of plants as small as Java Moss - imagine how cool that would be!
I think I used a tripod with most of the above pictures. Tripod eliminates handshake while taking pictures, and this helps you eliminate any blurring in the pictures. They come out looking clear and crisp this way. Angels are relatively easy to photograph as they can stay still in one place for a long time. My Angels seem to like me photographing them. They're curious of what I am doing, lol - always swim up to the glass and stare at me meddling with my camera, lol

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I was also manually adjusting light exposure levels and shutter-speed in the above pictures. Normally, pictures in a fish tank come out too bright and unnatural-looking. So you need to adjust the light exposure (I had to lower it to make the pictures show the tank the way it really looks). The faster the shutter speed you choose, the easier it is to photograph fast-moving little fishies like Cherry Barbs for example. As for my Zebra Danios ... forget it, lol. I'd leave photographing Zebra Danios to a professional photographer. I also have my contrast set to high in my camera, so the colors come out vivid. Looks much better this way than no contrast at all - then pictures come out dull and colorless. Lastly, Nikon has an auto setting for fluorescent lighting - if you leave it on Auto Daylight, it will pick up the fluorescent lightbulb's color temperature, and it will adjust it so that pictures come out looking normal - i.e. you don't have weird colors in your pictures due to fluorescent lighting (normally, fluorescent lighting comes out ugly in pictures).
Jim, I think you're talking about Canon Digital Rebel? I don't think Nikon has a "Digital Rebel" model.