I just looked at a profile for Sailfin mollies and they get quite large. The profile I looked at said 6 inches....so really that seriously limits your stocking (when you take the angel and shark back of course). I think the only other fish you could put in there would be a regular molly or 2.
Or you could return all the fish and start over with stocking. I personally like tetras. If you pick a type that gets around 1 inch, 1.5 inches, you could have a nice school of 6-8. Some smaller types are black neons, lemon tetras, flame tetras, silvertip tetras, cardinal tetras, and glowlights. If you don't like the tetra idea, you could go with some livebearers that stay smaller, like 4 platies or regular mollies....or 5-6 guppies. A tetra/betta or gourami combination would also work. Get 6 tetras of a smaller type and then you could have a male betta or dwarf gourami as your "centerpiece" fish.
Do you like any of those ideas?
Angels get around 7-8 inches tall and about 5 or so inches long. My biggest angel is about 6 inches tall and about 4-5 inches long (counting fins). She is big and lives in a 55g tank. The minimum for 1 angel is a 29g tank....just to give you an explanation as to why they can't live in a 10g.
Did you get your fish from a local fish store or a pet store? Did you tell them your tank size? I'm just wondering because it is amazing the fish that stores sell people for small tanks. They should be better educated. That's why its best to get on a website like this one and research before you buy. Now that you know about this site, you can ask about any future purchases.
