Yeah it looks like a mudskipper/goby that i have. Apocryptes Bato but i'm sure that it is not the same species. From the way its eyes are located, more than likely it's a mudskipper. Might be fine in freshwater but maybe safer if brackish. Good luck
That link cracks me up. The seller has NO CLUE what they are, how they are kept, grabs at straws to guess how they will breed - yet will send you 2 sexed pairs. He assumes a lot, doesn't he?