The "snake" might be a loach -- possibly a yo-yo loach. Here's a good website: http://www.loaches.com/species_index.html
I'm not sure about the crab. Maybe a fiddler crab?
To post multiple pictures in one post (three is the limit for one post), just click on the "browse" button again to find another picture, and then click "add attachment". Just do the same thing that you did for the first one over again. You won't see all the pictures when you do the preview, but if you clicked on "add attachment", they will be there when you click submit.