These images are quite stunning!
What makes them great images is that you have close-up, centered shots of unusual sea creatures, well lit, and in focus.
Yes, the colors are a little oversaturated and maybe the contrast is punched a bit too high here or there but these are mainly post-production issues...or could be appropriately solved in postproduction (Photoshop, Lightroom etc.)
My suggestion for improvement, however, is that they are what they are: close up pictures of fish, shrimp etc. that are centered in the frame.
If you look at most of your photos - both horizontal and vertical - you center the subject as much as possible.
So your end result is documenting extraordinary creatures using ordinary composition.
Now that you have these shots, I would experiment with off-framing the creatures, and getting parts and pieces of them instead a center framed fish up close.
I have no doubt that as you continue to take underwater photographs you will improve in this regard as you will get bored yourself, of taking the same sort of composition when you are underwater.
Keep it up and definitely post more here! You're well on your way to making some really impressive images.