You really need to up the numbers of each type of tetra to at least six. Schools of a dozen or more look nice. And I, personally, would ditch the black skirt. No matter how many of those suckers I've had, even up to a dozen, they still nipped fins. I will never own them again. Some apparently have better experiences with them than I have had.
Yep, you have a bit of a tankbuster in the tri-color shark. You'd be better off without it. Also, the advice about the plecos is right on the money... commons will get too huge, and I think you might already know if you had a bristlenose, by -- yep -- the bristles.
You know, dojo loaches are fun to watch, especially when you have more than one of them. They enjoy having others around, and they chase each other up and down the tank, and sometimes they all pile up together for a nap. They're funny-looking buggers; I named mine Larry, Leonard, and Lloyd. I had them in a 55 with my goldfish. They're from cooler waters, so you really shouldn't set your tank temp higher than 75 or 76 degrees with them in it. Also, you need to make sure your substrate is not made up of sharp-edged particles, as they tend to burrow. This is true for bristlenose plecos as well. Small-diameter gravel and sand work nicely for them.
I don't see why a gourami or an angel wouldn't work as a centerpiece fish, although there is a chance that an angel could snack on your smaller tetras. Also, it's good to have tall plants, either silk or real, to help angels feel comfortable... or so I've read. I've researched angels quite a bit, but never quite taken the plunge of acquiring them. Lots of plants should give the tetras some hiding places, though.
Question: What is the history of this tank? How long has it been up? How long have the current inhabitants lived in it? Has it been trouble-free? Depending on the answers, it might not be an appropriate time to add *any* fish. Patience is definitely an asset to a fishkeeper.
