bully fish, dont know what it is though!

[courageous_stumbling]

Hey, I know I'm not on here all the time and I dont really know you guys yet. But there is a fish in my tank called Jack.
CLICK HERE TO SEE JACK
This fish is always cruel to Dassian.
CLICK HERE TO SEE DASSIAN
There are 7 fish in the tank and Dassian is not the smallest. I bought these fish together and they got on fine for ages, I was wondering if its maybe something stupid like Dassian a girlie in heat and Jack just horney, but its lasted for a few montsh now. The reason I've left it so long is that Dassian is never hurt and doesnt seem too disstressed by it all. But now, the little darling spends more time at the planty end of the tank, hiding away.
Does anyone know what type of fish they are and maybe know how to stop Jack bullying dassian? I'd appreciate any help.

 

[CFC]

The first is a kissing gourami and the second is a red rainbow. How big is the tank? Kissing gouramis can be territorial and aggressive when kept in smaller tanks and as they grow the aggression levels grow too.

 

[courageous_stumbling]

My tank is 4' x 1' x 1.5' and it's ruled by Oscar. This photo is older and there are only 7 fish in it now. Do you think it's a bad idea to keep him? I wouldnt want to give him back to fish shop but I suppose I would if he turns nasty.
CLICK HERE TO SEE TANK

 

[SirMinion]

There's goldfish in your tank?

 

[courageous_stumbling]

There did used to be goldfish in my tank, from back before I went tropical about 7 - 8 years ago. They not around now, but I can confirm that upgrading cold water fish to tropical fish doesnt harm them or shorten their lives. Infact I found that it makes them more active and seem happier if you know what I mean. At the moment there is Jack the kissing gourami and dassian the rainbow fish, an oscar, ariel the gouamri, atom the albino plec and the dude and the janitor the plecs.