The Serpae Tetra is a schooling fish and doesn't usually do too well alone. The glowlights and neons usually mesh well together and form a school (my Black Neons took several weeks to start schooling with the glowlights I added later).
Anglefish usually like a taller tank; how many gallons is yours? Keep an eye on your Nitrite and Nitrate levels (the Nitrogen Cycle), so they don't spike too much with that load. What kind of filtration are you using (hang on the back, canister, etc.) and are you using all 3 stages: chemical (charcoal), biological (bio-wheels, etc.), and mechanical (filter floss)?
You also want to check the pH levels of your water and see what your fish prefer. Cichlids (your Angels) usually prefer a harder water than other tropicals. You don't really have to get too technical with your water quality, as long as you're doing regular water changes every couple of weeks (that helps keep the Nitrates low and prevents algae blooms)
Have you thought about adding a school of Corydoras Catfish to your clean-up crew? I used to raise Peppered Cories for awhile, once I found out that I had a breeding pair. They really have a lot of character.
I concur with staying away from the common Plecostumus, as they can exceed a foot in length rather quickly. There are a few species that remain rather small though. A nice school of Ottos would keep your algae in check and they are quite small; though they can be sensitive to changing water conditions. There is also a type of freshwater shrimp, called Amano Shrimp that will eat algae; but they are a bit more expensive than the standard ghost shrimp.
A good site to go to with any questions that you have concerning care of your little fishies, is:
www.fishprofiles.com
It's a very friendly community.
Edit I looked at your pics; it looks like you've got a standard 10 gallon with a HOB Filter (Hang On the Back).
-Keith
