I've taken thousands of fish photos with my digital cameras over the years. Here's a few aquarium photography tips that I've learned along the way that will hopefully help you take better photos of your fish and aquariums.
1. Buy a digital camera! Digital cameras are great to use for taking photos of your aquarium. A digital camera allows the photographer to take as many digital photos of the subject as they like, without the high cost of developing film. Unlike a film camera, you will get instant feed back on the results of your shots. Finally, you can edit and adjust your photos in photo editing software programs like Adobe Photoshop Elements 11
2. Expensive cameras are usually better at producing higher quality photos. Try to get the best digital camera you can afford. Companies like Canon, Sony, Olympus and Nikon make excellent cameras. Here's a couple of good camera review sites to help you find a quality digital camera. Digital Photography Review and Steve's Digicam.
3. Purchase a digital SLR(Single Lens Reflex) camera. It's more expensive than a compact point-and-shoot camera, but will take higher quality photos. A digital SLR camera allows you complete control of all your camera's settings. It's the perfect camera to use when you need to shoot fast photos in a low lighting environment. In addition, you can change lenses and use external flashes on all SLR cameras. High end point-and-shoot cameras can also take nice photos, but for the best results an SLR camera is the way to go.
4. Thoroughly clean your tank the day before you want to take photos of your aquarium. Wipe down all sides inside the tank, including the bottom. Also, clean the outside front of the aquarium. Vacuum out any debris you might have in your substrate. You might want to clean the filters out as well.
5. Use a diatom filter. A diatom filter like the Vortex D-1 Diatom Filter
6. Use very strong aquarium lights under the hood of your tank. The more lighting above your tank, the easier it will be for your camera to focus and take clear photos of your fish. You will need very strong lighting if you decide not to use a flash. Be extremely careful when handling lights above your aquarium. Shock or electrocution can follow if the lights or cords get in contact with the water.
7. Increase your ISO setting on your camera if your photos are blurry due to poor lighting. When using high ISO settings, the camera has to be extremely still to get good results. You just might have to use a tripod if your shots are always filled with noise.
8. Try using the "macro" mode feature on your digital camera. Almost all digital cameras now have a macro mode. The macro mode is used for close ups and will produce better, sharper photos of your fish.
9. Buy a digital camera that allows you to save photos in a raw image file, rather than just a TIFF or JPG file. Raw files have a higher image quality and have no loss of data from file compression. You'll also be able to make more adjustments to a raw image file. The downside is the files are rather large.
10. Buy a good photo editing program. Software programs like Adobe Photoshop, Adobe Photo Elements or Corel Paint Shop Pro can help turn mediocre photos into beautiful works of art. These programs can help eliminate common photos flaws that will make you a better photographer and save you lots of time. Adobe Photoshop is a very complex and expensive program that is probably overkill for most amateur photographers to use. I'd recommend using Photoshop Elements 11 or Adobe Lightroom 4. Both are excellent programs with lots of great photo editing features that are easy to use.
11. Don't try following the fish with your camera as they swim. Instead, focus on a specific spot in the aquarium and wait for the fish to enter into your focus zone. Moving the camera back and forth might cause your photos to blur because of the movement.
12. Use a tripod to steady your camera. It might take awhile before you get your fish to pose for the camera. After awhile, fatigue might cause you to move while you snap photos. Movement can cause blurry picture results, especially if you are shooting with an ISO setting of 800 or higher.