I have a 135 gallon tank (6'x18"x25") which is currently home to a 10" flowerhorn. The tank looks very empty, and I am considering adding a managuense of similar size to the mix. I was just looking for others' experiences or input on this. I am unsure how the aggression will pan out. I plan on taking the fh out and rearranging the tank before adding the manny. Thanks in advance for your help!