Another new Betta! Yay!

[buttercup132]

He's eaten a couple of the neons because they're so small... but I don't like them anyway,

WHAT THE ...!!! I'm sorry but I think youve just written that KNOWING it would cause a argument.
That is in no way something to be posting on here!
Thats like saying "Oh my dog got attacked and killed by a bigger dog but who cares I didnt like him anyways" And the new one is better. So that makes it ok that the poor fish had to go through that pain because you didnt like them!!??!?!

[Christmas_Hamster]

Lets not start an argument. What we can do instead is help correct the problem so it doesn't happen again. We can do this by suggesting to find a nice calm boy/girl betta and then watching them for a few weeks to see how agressive they are. If they seem to mean then don't add. But if they seem fairly calm then gice it a whirl. But fish eating other fish is a problem with keeping communtiy tanks and a risk that need careful thought.

[IRescue452]

Are you or your dad experienced in fish at all? Neon tetras are one of the most fragile fish you can buy. They probably won't survive the cycle.
You really should have waited until you found out the personality of the betta. You can mix aggressive and placid tropicals, but you'll want to have a tank that is big enough and a stocking plan that doesn't cause much stress to the small fish. Tetras are a schooling fish and you should always have more than a "couple" in a tank with a potential predator. Platies can do fine in that water. I consider them a coldwater fish but they can live in trop tanks.