Cool frog! is that yours? is it a Dendrobates azureus? I have a D. leocumelas...they're such cool animals
anyway, I think you did an amazing job of capturing the pattern of the frog's skin onto that gaunt. It needs to be a bit brighter, but you said that it is brighter in person, so it's probably perfect. However, in my opinion, that base doesn't really go. Try modeling on some moss or fake water or a more riverbed-ish rock scheme