Im thinking of Africans cichlids and as far as filters I went with a 50g Penguin filter. I was also looking at the spiny eels but they didn't seem as active as the "moray".
How active a spiny eel is depends alot on thier personality. Like every person, fish have different personalilites. I have two different types of spiny eels, a peacock eel and a zig-zag eel, both which stay around 7 inches. I have one who is active all day while the other one does nothing but hide, burried under the substrate all day. They are really fun during feeding time. I do have to admit that I really like the morays but I don't have the ability to house one as of right now!