my babies have had thier first fight tonight.. they have been co-existing quite happily for almost 5 months now. They both seem to be growing really well.. we moved house with them 5 days ago but they have been fine all week. Could it be delayed stress? They are not off thier food. Could it be adolesence? should i be considering getting another tank? does anyone have any ideas? please help...

oh yeah.. tiger keeps going really light in colour and then dark again, is he being dominated or is he the agressor?

They are just re establishing the pecking order. It normal for this to happen after a move. Many things can start this off, moving the decor around or even adding a new fish can cause fish that have been fine to start dong this. The lightening of the fish is something they do, mine do it sometimes when im moving decor around to clean under it