Beautiful colors and lighting, Horacio. The frog is nicely captured and has good detail throughout. I agree with Robert about smoothing out the BG - think that would really help put all the emphasis on the frog where it belongs.
Horacio,
I agree with Robert's and Jules' comments, and would add a suggestion to darken the upper left background.
This looks like a relative of the leopard frogs we have here in the US. They're one of my favorite amphibian subjects; colorful and with very interesting patterns of markings. You have a nice specimen, well composed, and I especially like the eye-level perspective -- engages the viewer very well.