Hm... I guess one of the only things I see that is catching my eye as wrong, is that his left leg (our right) is pure shadow. Maybe the back of his leg could be slightly lit up, because the apparent light source is coming from the left, and even though the leg is behind him, the light source will still hit the very back of his leg, but probably not the front. Or, it could possibly be the top of his thigh, though I would like to hear other peoples suggestions on this part.
i understand and agree with you. there should be some light hitting that back leg...thanx
Nice, you have a good start with anatomy. I would say work on foreshortning, the pose would be a little more interesting if he were pointing a little more towards us.
One thing thats subjective is comparitive anatomy, since its a sea creature maybe use your knowledge of anatomy to play with the shapes a little.
Maybe parts of his legs or arms are more tubular like a fish, odd proportions go a long way to making him feel more 'creature like'. Right now he looks almost 'too' human.