Well, I dare say you've found one of the best resources to educate yourself! Plus, a site like this is always willing to help out a member who obviously cares as much as you do
Now, let's clarify. In the wild, angels eat neons as a food source. This behaviour is commonly seen in the aquarium as well. However, there are instances when, if an angelfish grows up with neons, from a young age, it will not see the neons as a food source. Several people succesfully keep the two together....it isn't a 100% positive that they'd be eaten and it wouldn't necessarily be considered "bad fishkeeping," I don't think. If you'd prefer not to take the chance, then taking the neons back or getting another 10g tank are valid options. (If you have the room or desire for a new tank, a 10g would hold the 9 neons and four frogs very comfortably!!

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Also, while Angels can be aggressive sometimes....again, it is not a positive that they'd harass your frogs. I do not think it is the best situation...but it is likely to be do-able. I guess it depends on how much you want the frogs and your willingness to see what happens. If you do keep the frogs, you really shouldn't get any other bottom feeding fish though...
Do you know what kind of sucker fish you have? Is it small (an otocinclus), larger (Chinese algae eater) or maybe something else? Is it a pleco?
As for what to go in the tank...you could probably do something like kuhli loaches, cories, or even a pictus catfish (all very cool fish, indeed). I keep an african butterfly fish with my angel in a 29g, without any problems, but sometimes you hear of an angel that bothers the long fins of a butterfly fish.
Another option is that if you are the type that doesn't get too attached to the fish, you could simply keep the neons and replace them as they get eaten (keeping the angels well fed to avoid the temptation of snacking on them).
Hope that helps some. Also, some of the best advice we can give here is not to listen to anything the petstore tells you! If you think it could be true, come here and ask us and we'll let you know for sure
