Well, first I need to say that you should do something to your older fishes before you take any new fishes.
It's a terrible mess. First you should try to find new home for Clown loach and silver sharks (if it's balashark,
Balantiocheilus melanopterus.) Both of them need much larger tank and both are shoaling fishes.
And what is "common pleco"?
Ancistrus sp.? Or huge pleco that need more space eventually - maybe
Liposarcus multiradiatus or something like that?
After all those, you still have quite a mess in your tank. Sorry about saying that, but it's true. So, best way it's to buy new tank, get rid of those fishes that you can't keep or you get rid of many of those fishes that you have and start building a new community where are also angels. ("Get rid of" means, giving fishes back to store or giving them to other hobbiests who have space to take them.)
(
Here is some pictures of
Liposarcus multiradiatus (It may also be
Liposarcus pardalis). This is my friend tank.)
