starfalls:
just my 2cents about the questions u posted about platties and the rest of ur fishys.
1. if you want to breed ur platties and ensure the safety of the babies, purchase a fry hatchery/ net breeding thing that will separate the pregnant fish from the rest of the tank. you would have to however identify the pregnant platty (fat female with a almost square like looking tummy), and chuck it into the hatchery which is of course just hanging by the side of your current fish tank. Once she gives births to fry, remove her and let the fry grow out a little before releasing them into the community tank.
2. or you can just go with the option of letting nature take its course. purchase some java moss and scatter a little around the tank. they make good hiding spots for fry to prevent them from being eaten. rocks and stones help too as fry will hide in the spots between them.
3. i highly discourage you from keeping the convicts in a community tank. even if its 2 females, they are highly aggressive and destructive in nature (plants). even without a male, they would sometimes lay eggs and that would mean they would because really aggressive and start defending their territory.
i like convicts too - especially the barred ones and i would really recommend you to keep a pair in a separate tank and watch them breed. the last pair of convicts i had bred almost once a month ! you'll get anywhere from 50-few hundred fry everytime.
4. im not sure if the lombardis could be picking off the tetras but im pretty sure the convicts will in due time. if you really like cichlids, the only ones i would recommend keeping in a community tank are the rams(blue/gold/german).
i believe the only community fish u cant keep with the rams are the guppies.
im not a professional fish breeder but have been keeping fishes for the last 10years or so. also, my info might not be 100% right so feel to correct me if i wrong.
sorry for the long post just like to help out