17. Wear solid, dark clothing so you won't be easily seen in the reflection of the glass in your photos. Discus can also be scared if you wear bold, striped shirts, which might cause them to hide in your aquarium.
18. Turn off the air pumps/filters while taking photos. You want the water to be calm while taking photos. Remember to restart the pump after you are finished taking pictures.
19. If possible, use an external flash when taking photos. You can position an external flash far away from the lens of the camera, avoiding the flash reflection bounces that will appear in your photos.
20. Make sure your camera's battery is fully charged and the memory card is empty. It's very frustrating to learn your battery is about to die or your memory card is full just when you are about to take that great shot. It's also a good idea to have an extra spare battery and a few extra memory cards with you when you start taking photos.
21. Have a background in your aquarium. You don't want to take pictures of a glass box. Seeing extension cords and filters and other objects behind a tank with no background will make a nice fish picture look bad. Purchase an aquarium background or just paint the back outside of your tank. You could also paint some heavy duty paper or cardboard and place it behind your aquarium as a background.
22. Purchase a camera with fast shutter speeds. You want as many shutter speeds as possible. Faster shutter speeds will help you capture quick movements by your fish much more sharply.
23. Search for photography forums and digital camera tutorial web sites on google.com. There are plenty of photography web sites that will have information to make you a better photographer. One of my favorite digital photography tutorial sites is ShortCourses.com.
24. Practice. Practice. Practice. Aquarium photography can be very difficult to master. The more photos you take, the better aquarium photographer you'll be. Experiment with different camera settings, different lighting, different lenses. Keep a log of the different parameters while shooting. Compare your log notes with the photo results so you know what works and what doesn't. Eventually, you should find the right settings for your environment to get high quality photos of your aquarium.