On my screen it looks good, but I know that my screen is bright and nice ... and I tend to give my photos some - what I take to be - GOOD contrasts often enough, and to present them a bit darker much rather than too bright ... and then, while over in the UK and using other people's or public internet station screens, I found my photos showed extremely dark in places ... black really.
So it will really depend on who sees this picture and on what sort of monitor/screen if you will get a "yes, it is too dark" answer or a "I like the intensity of the colours and the contrasts in this photo" answer.
It does lean a bit on the dark side, as you yourself are saying, but on my screen it is absolutely ok. It suggests some either early morning or evening light. Nice light which gives good, deep colours. The ISO number suggests it was actually getting dark by the time you took the photo, but I can't see any noise from it, which is good. You achieved the desired DOF with the aperture chosen, which I also like, and I find that the black and yellow of the turtle contrasts nicely with the green of the background (give me a green background and you'll have won me over, anyway

).
So yes, I like this.
Whether this is a "good photograph" per se (by definition) is not for me to say. I am all unskilled in the field ... all I can say is if I like what I see or not. Sorry `bout that.