Thanks for all the comments and concerns. I don't have the accommodations to quarantine fish for long periods of time. I just buy only very healthy looking fish and hope for the best. I have never had a problem before. (I know some people might disagree with this, but it's how I've always done it).

I introduced the new fish after syphoning the gravel with the lights out, so everything was moved at the time and the angel was more concerned with the syphon. I guess that's essentially the same as introducing them after a feed so they can "sneak in undetected".

Ginevive - I agree with you about the plecos. That's another reason I don't like them: they get huge. I feel guilty keeping them in such a small tank. I also love how you said "snake" when you meant to say "snail". Shows what you usually deal with. -lol-

As for the apple snail, I've done a lot of research and think I'll be alright with him. I stumbled across this website if anyone is interested. LOTS of info. http://applesnail.net/