I have a 29 gallon with 6 Cardinal tetras, 3 Platies, 1 Bristlenose Pleco, and 4 Amano shrimp. I'm looking to add something new to the tank. It's been setup for years, so it's established. PH is 7.2 and I tried GBR's once, but they didn't live. I'm assuming the water was too hard for them. So give me some ideas on a "centerpiece" fish or two I could add to the mix. I'd like to add something that is a little bigger. Something that gets at least 3 to 4 inches perhaps.