i do, i actually have 4 right now. 2 F8's in brackish, GSP and a Neon/Spotted Sharpnose Puffer in my marine tank. plus i want my congo for my empty 29 or 45. i think i might get the ceylon, hes small, about the size of a full grown F8. and like i said the main reason i got rid of the smaller GSP is because he would seem to stress my big guy out when he would seem to want to bully him a little. i loved having both of them, and my friend loved my puffers, but i wouldnt get rid of the bigger of the two so he wanted the other GSP. which im glad he took because i can still see the fish, help him out etc. but now since i got rid of the smaller one, my bigger GSP of the two i had seems to be depressed or lonely even though he has other tankmates he hasnt been acting the same. i tested my water to see if something is off and that has something to do with it and everything was within check.
after i move i plan on getting at least 100G to upgrade my buddies too, and then use my 75 probably for the sump/refuge, glass is scratched up from previous owner so i dont want it as a main tank anymore