I just have a quick question about the tankmates for my Betta. I currently have Sparks, (my VT male) in a 10g with a red-tailed shark. I am hearing conflicting info about whether this is an ok pairing, some saying absolutely not and other places saying yeah they should be fine. So far there has been no issue at all between them, but I'm worried this may be an issue later. Can anyone help?
The emerald cory will actually become an issue. Those are one of the biggest species of domestic cories, getting to about 3 inches - too large and too active for a 10 gallon. As mentioned, they also need schools of 5+, so you either need to rehome him or upgrade. :(
Aw sorry to hear about the shark! They're gorgeous fish. s-i-p.
Ok, so once you figure out what to do with the emerald cory you might be left with a 10 gallon and a betta. This is fine. To answer your initial question then, a 10g can support a small sorority of female bettas (NO MALES present) or you can divide it and have the male on one side and a few females on the other, divide it three ways and keep 3 male bettas, you could return the emerald cory and pick up 4-5 dwarf cories (all the same type as they like to keep together). You could go with some mollies or certain tetra's but some of these smaller zippier fish like to nip long flowing betta tails.