I'm very didagent with the water changes, and mine is in a 70 gallon.
I don't think that they are weaklings, they just like good water like any other fish. I don't do anything different with my blue than I do for any other fish I have, and it's all good.
He/she is in with male jack, that was the same size as the blue one when I got it. Now the reg jack is twice the size of the blue, but he's not the boss. The reg jack is 5" now, and no signs of pairing off, so I'm left to guess that the blue is a male too.
I have noticed that before the night time feeding my blue shows the best blue colour....has anyone else noticed this?