Adam, I agree with you as far as bouncing the light is concerned. As you guessed, I did not have such gears. I usually use softbox, which I did not have at that time either. I should say the frog was behind a thick glass and the environment was very dark, so dark that I had difficulty focusing the camera on the subject. In addition, the frog was at the same height as my head.
The light looks a bit harsh. Did you use an on-camera flash? If so, it might have been better with it on a bracket from above. I realize most folks don't go to the zoo with a flash bracket and everything. Maybe just a cord and hold the flash above.
For these kinds of shots, I try to bounce the flash off a card to make it a little softer and not get the catch light right in the middle of the eye.
0 
