PLEASE don't mess around with combining fish with designations of aggressive and semi-aggressive, there is a HUGE difference between the two group. I'm a Gourami fan and for the most part the dwarf version are "peaceful" while the larger sizes (with thankfully a few exceptions) are "semi-aggressive". It takes a long time for them to get along together and often one of the poor peaceful group get constantly harassed - some to death - by there semi-aggressive cousins if you don't do something about it. I happened to have a tank of a few gourami that did get along, although there were some dominance issues at first. Then I purchased a tank's worth of the larger gourami's without realizing that 3 or 4 were "peaceful" and the rest semi-aggressive. I HATE watching that tank at feeding time. I do as much as I can to put food in as many different locations as possible to try to keep the fights down - those poor peaceful Gourami's have to fight for their supper every day. All other species (such as cory cats, loaches and my beautiful lemon bristle nose are left alone 99% of the time - in fact the bristle nose will just "freeze" or jump into a cave nearby while the Dojo loaches just lay on top of their pellets and wait for things to pass so they have put tabs on their own food. The rest is a pain to watch - some of my favorite gentle fish at any other time turn into monsters at feeding time. I have a tank nearly cycled so I can pull out the peaceful fish ASAP - it's so close I can't wait.
I would think the group most famous for peaceful, semi-aggressive and aggressive would be the cichlids - they are a VERY popular group because there is a huge variety of very interesting and colorful fish, but I would never mix my Gourami semi-aggressive with a Cichlid semi-aggressive - I suspect the fights could get quite nasty. My semi-aggressive Gourami's fight with other semi-aggressive Gourami's constantly - feeding time or not - frankly it's just boring to watch but they are still my responsibility. I would trade them in an instant for less aggressive fish.