halfmoon king betta

I was at my LFS today to get a filter, and saw they had a bunch of Longfin Green Dragon Bristlenose Pecos. I REALLY want one, so I am going to rearrange my tanks tomorrow to find room for one. The tank I want to put him in is a 20 gallon high tank, it has a Quietflow 30 on it. Ph at 7.4 and my...