I dig the Krusty Krab!!! But FYI: I went all out on the Spongbob setup about a year ago: Got Spongebob & Squidward's house, the Krusty Krab, and like 5-6 figurines. I was very disappointed at how quickly the color came off. Yeah, I have a pleco - maybe it was him, but I spent almost $100 for everything... and it all lasted less than 6 months. blech.
But more on point, I agree with the other posts; anything fun with high light demand like glossostigma or dwarf baby tears will just wind up growing UP to the light (instead of spreading out horizontally) if you don't have muchos lighting. Java moss or similar might be the best choice right now.