both puffers can grow to a decent size and will likely end up fighting. my GSP was one of the most interesting fish and by far the most determined hunter. he slowly but surely hunted every tankmate and tore the fins up until they couldnt escape and he would eat them. also highly recommend adding salt until they are in full SW and they are much more healthy. i know everyone says to wait but i had mine in 1.025 after about a month and he was maybe 1.5 inches. snails and other shelled food are great. wouldnt recomend for a beginner