I don't have much to say about the content/composition.
But for opinions sake, I don't think that the starfield should be in front of the clouds, it should be behind them.
If Whales are to be flying in the clouds, the water could be hard to explain. They should be breaching the cloud tops and not solid water.
The Whale on the left seems to be missing his left side flipper.
Perspectively speaking, the left side Whale would also be much larger than the other Whale since he's closer to the viewer. As it is they appear to be in the same perspective plane and there's no perceived depth between them.
Here's an example of perspective. (note no water here either)