Evan1

HahI gues si have a lot of questions today. My rainbow shark is getting more active when it comes to chasing fish around. Whats going on?

Dino

As they get older, they become more territorial.

Typical shark behavior, nothing to worry about unless he is really hasseling your other fish.

Adding more hiding places may cut down on this behavior.

Dino

Jason

You should look at the hasseled fish every now and then for any signs of over agressive behaviour like tattered fins etc.
My red-tail always picked on my chinese algae eater but now the tides have turned and they've been fighting lately and the shark was the loser and the algae eater has the tank now. But the shark is gradually getting his strenght back and looks certain to restore himself to the top.

Evan1

I noticed my rainbow shark picks on my pleco the most out fo the other fish. All the pleco does is suck the glass and mind his own business.

Jason

Pleco should be ok they're pretty tough little guys