Freshwater aquarium

We have a 55 gallon freshwater tropical aquarium in our dining room/study/front sitting room. Our large angelfish recently passed away, so we will be looking for a few new angels soon. We originally bought 2 angelfish, hoping that we would have a male and a female, but one of the 2 died shortly after we brought them home. After that, we were too concerned about aggressive behavior to get another. We also have 2 smaller cichlids that are quite social, tolerant fish. They seem more interested in/curious about the other fish than concerned about defending their territories. We also have at least a dozen tetras, some blood-fins and some black skirts. We of course, have a plecostomus. Also a flying fox (I love this fish and wish I could find more) and a Chinese algae eater. The Chinese is the most aggressive fish in the tank and is definately the bully. He chased our dwarf orange flame gourami to death. Little bugger! We considered bagging that stinker, but then realized how great of a cleaner he was/is, so he stays. Last, but not least, we have a bala shark. He appears to be some kind of a sucker, with the appearance that suggests a slim shark.

I'm constantly fighting the slimy algae, but at least the water is crystal clear. I carefully pull out the algae from the plants and roots every other weekend. This is a planted aquarium with a couple of philodendron cuttings hanging in the water. The philodendrons love the tank, although they don't like me pulling the algae off their roots. I do try to be gentle.