Sixline agression

[Fishko]

In planning on trading my sixline, but i was wondering how should i catch it. I know where it sleeps at night. Should i try capture it at night? I want to add more fish, am going to qt. Just the guy flairs up at my other fish. But they dont fight

 

[Spare time]

I would catch him during the day. I once gave a fish a heart attack going into my tank at night and it actually died. Althought if he just flares up and doesn't attack the fish I personally wouldn't get rid of him since fish will do that regardless.