Blue Gouramis and Aggressiveness

Question
Im trying to achieve harmony in my 55. Original mates included 2 mollies, 2 blue gouramis, a blue catfish (6"), upside down catfish (4"), and leopard pleco. The gouramis were at each others throats so I removed the more aggressive one (3-spot, female I think), and the other (male opaline)calmed down immediately. The 3-spot is happy, alone in a 15 gal, but getting big... I decided to get another 3 females (opaline), thinking if the gender ratio tilted more to the harem I could have a little group. They are such pretty fish. After the 2-week QT (during which they were fine together in a Rubbermaid tub), they were added to the 55. The guy in there was immediately aggressive to all the others and, not wanting them to be excessively stressed, I removed him. Any thoughts on how this might work out? The 3 new guys seem fine together. (maybe they're friends?) Could I add either of the 2 exiles back in later or is that just going to cause the same problems. I worry about switching tanks too much. Did I just make things worse getting the new ones? Should I add more live plants for hiding places? Thanks for your expertise, in advance.
Cheers,
~Mia

Answer
Hello Mia -

In my experience, I've noticed that gouramis of any variety do not like other gouramis being introduced into their territory. If you want more than one, it is best to introduce all fish into the environment at one time (like you did with the new trio.) You may be able to get all 5 fish to coexist peacefully. The best way to do this would be during one of your water changes. Get a large bucket and fill it with equal parts of tank water from all of your gourami tanks. Place all 5 gouramis into this bucket while you do a water change in the 55 gallon (it doesn't have to be a complete water change, just 25% or so.) Allow the gouramis to mingle in the bucket for 20 minutes unless there is excessive violence. Then pour some of the water from the 55 gallon tank into the bucket to allow them to get used to the new water. Once you feel they are ready, scoop them all out of the bucket and introduce them into the 55 gallon. Don't pour any of the bucket water into the 55 gallon. Watch their behavior closely. It is normal to experience some fighting, nipping, and chasing until the new hierarchy is established (this should take a day or two, no more than a week.) Some fish just can't coexist with others, but in your situation you should be able to establish peace, especially with a school of gouramis versus just a few.

Hope this helps,
Amber Worman