Killer Bagghi!!!!

[mark97r6]

Hey guys,
I bought 4 bagghi Cardinals from the LFS abot 5 days ago in the hope i would see a pair from them.
The best i could do with sexing is i selected 2 of the smaller ones and 2 larger ones!
The tank is an 8' 360g. After about 2 days one of the smaller fish wasnt looking so good, i didnt witness any harrassment but he cowered in a corner all day long, so to no avail i attempted to catch this fish and move it to one of my other tanks.

The next day the fish had disapered - i exspected this!
the remaining three spread across the tank.
One would hover bang centre and one would hover in the middle of each end. On occasion two would swim around each other (not always the same two)! But all 3 fish ate well on frozen and flake, and were of good bodyweight, and their tankmates are completly peacefull.

Today i have one left!!! !!!
It is the biggest of the four, what happened??

Is it obvious that i got all the same sex (i didnt see this a prob in this size tank)?

Have i just got an evil bagghi?

Can i safetly introduce more to this fish (doubt it)?

I am really gutted with this as i intended to have a go at rearing these fish. If i move this one to another tank and keep it as the sole cardinal, and added another group of 4 to the 360g tank am i to exspect the same? Am i doing something wrong?

Thanks for the help guys, i feel really guilty about losing these fish, especially being how they are endanged! I am really aprehensive about repeating this.

Any thoughts on where i went wrong?

Cheers
Mark