That's the beauty of 'digital'.
I still have trouble with the focus on these little cameras. But I've found with macro, that after the auto-focus has locked in, if I pull back about an inch, then take the shot, I have more success in catching a clear subject.
Most photography books (and Nick) will tell you that sharp focus on the eye(s) of your subject, animals, fish, and people, is an absolute essential.
If you have those little green focus targeting things, in your camera, note where they lock on, on the overall body of your fish, then pull back the estimated difference, toward the eye of your fish. Then, without refocussing, complete the shot.
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Angels, Black Mollies, Bristlenose', Clown Loaches, Cory Aeneus, Gibby, Guppies, Hockey-stick Tetras, Keyhole Cichlids, Otocinclus.