55 gallon fish help

I previously had a 55g aquarium with tropical freshwater semi-aggressive fish in it. Sadly a large amount of diseases broke out in my tank even during the treatment. All but three fish died. I redid the entire tank and cleaned everything and replaced all filter equpiment. I basically started over. At this moment i have a:
4" tin-foil barb
4" african butterfly
3" plecotomus (or however you spell it)

I just bought a 4" clown knife fish which is in the quaratine tank for three days before i put it in my main tank. I am planning on buying a:

2x bala shark
ghost knife fish
2x other small semi-aggressive colorful fish

my question is do you think that this is too many fish for the tank? I have a emperor 400 filter. I am gonig to do a 25% every other week. IF you have any comments or ideas for the other two smaller fish then let me know. I prefer if there max size is like 8". Thanks a lot for helping me out and if somebody emails me on how to post pics i will put up pics for you. Thanks
Semper Fidelis,
Eric

55 gallon tank

the bala sharks will get 13"
tin-foil will get 15"
clown knife will get 40" (i will have to sell it)
african butterfly will get 5"
ghost knife fish will get 15"
algae eater will get 10"

I am not planning on any of these growing to ful size and i am sur ethat not all of them will survive to get to the full size. If they do i can always sell them....