I got my flowerhorn two weeks ago and it all of a sudden started having
vertical stripes on it. When I brought it there was no stripes. Does anyone know why?
It's actually the opposite. Most flowerhorns have the ability to change color variations. Many times this happens when they become aggravated. Flowerhorns tend to get more colorful the more pissed off they are. Some people at shows make it so the flowerhorn can see a reflection using mirrors or something reflective, so the colors will come out.
How old are yours? If they are still fairly juvenile, then this is normal. They will keep doing that for awhile. Stress actually makes them appear pale and colorless. They will lose all colors and turn light greenish. The lines become prominent when they start getting very aggressive towards other fish.
well it can be stress but when mating that is not stress and they stay that way,put a mirror against the tank and you see a change of color this not because he is stressed out from poor condition or health problems he is pissed . bars does not alway mean he stressed he can be it great health good water conditions not breeding just pissed