Corys are shoaling fish and should be in groups, in the wild they school in 1000's.
It would be cruel to keep a schooling fish in groups 2 or 3, they would feel insecure and wont be happy.
Lol im not quite sure but I think your other fish prefer temp around the 24-25c range, I dont they will do well at higher temps as GBR do.
GBR are also very sensitive to water conditions and have been known to die for the stupidest of things.
GBR require high temperatures or they wont live til their full life capacity, they can live for around 5 years or more, if the temp is not correct they will last a lot less than that, how do you know the fish are healthy, do you talk fish? Lol :)
Why not rehome the females, sell them or give to a lfs. No need to kill them
Because a guppies fancy tail would make a betta think its another betta so it will tear it apart and cause war.
Well ive personally seen parrots try to eat small enough food to go in their mouths and they just cant, I use to handfeed my parrots to make sure they eat.
Use photobucket and post the IMG link here.
If the guppys fat, its most likely pregnant Lol.
http://www.fishforums.net/index.php?/topic/88199-livebearers-faq-topics-and-guides/
Males are colorful, means are mostly dulled out and silvery looking.
The GBR requires higher temperatures than your other fish appreciate, GBR need a temp minimum of 28c to thrive, also I would up the numbers of the corys.
I would up the number of corys .
What temp do you have your tank at, GBR like their temps higher than most of your stock.
I would add a male GBR and leave it at that.
Make sure to up the corys though.