Can i add a spotted puffer to my tank???? i have a(look below)?

I ume that you are talking about the fresh water version of the spotted puffer. The biggest problem you will find is with fin nipping. Puffers can really nip. People think of piranhas as being the great white sharks of an aquarium. I find that customers who want to see carnage are disappointed with them. Put a goldfish in with a bunch of marine puffers and you get results. However, the little green spotted puffs aren't as terrifying but they will be a good match for the J. Dempsey. Why don't you get a couple knife fish and some clear plastic tubes instead? BTW who is telling you that your fish shouldn't be together? It's a lot better than the soccer moms who buy goldfish, angels, barbs and get upset when I tell them that they can't possibly put a parrotfish in with them.