I'm using an Olympus C-3000...which was an average camera when I purchased it. Now it's probably considered pretty cheap. It is 3.3 megapixel. I've found that the best thing for pics is...try different things. Lighting/settings/angles. Take 100 pics...and expect 1 or 2 keepers.
1st of all...get a tripod. The fish move enough, without trying to keep the camera steady. Next, try the Macro setting on your camera. With a digital camera...sometimes you have to move the camera to get things in focus. Most important...be patient. Trial and error/experimenting/and LOTS of pics is the key.
Ah by the way, you may find a post reply of mine in this Catfish & Other Bottom Dwellers category too! Its name is about Clown Loach I don't remember, not my post. There are several photos of my tank there.