Well, I guess i'm just the luckiest guy there is. Bought a pair of GBM's that were the same size. I've had one in my small tank at home that was a bit bigger.
So here's how it all shook out. I had added a GBTA to the home tank, the bigger GBM wanted nothing to do with it. Well the two similar sized GBM's fought like crazy as soon as they hit the water together. Sooo...dip the less aggressive one out, take him home, destroy home tank getting bigger GBM out, add smaller from work, drive back to work, add the big one. Whew!
So, the small one at home has taken with the GBTA, sleep in it, feeds it...perfect. I got lucky. The two I put in my office tank? Yeah, they're paired up nicely. Sleep in the same cave, rarely very far from each other. All this in two days. I should go hit vegas while it's so good. LOL
