Need advise on fish

[Bigge_al]

I went to LFS and the advise I got concerning my fish plan was different than I was thinking so I figured I would check with the site.
I plan to have Mollies, Platys, and tetras in the same tank.
I was told that the combination would not work out because the Mollies & Platys require a high pH and salty enviroment and Tetras need low pH and no salt.
The other fish I plan to add are 2 cory and 1 otto and betta?

Was told absolute no to betta but was also told with large tank may be ok.

 

[SwimsWithFish]

They were right about the mollies. There brackish fish.

 

[jetajockey]

Mollies and platys do not require high salinity. They can be brackish or freshwater.

 

[siva]

A betta may be fine with those fish.

Corydoras will do best if you stock them in a group of 6, and oto's should be stocked in groups of atleast 3 to a tank that has been running for atleast 6 months.

None of the fish we are discussing need any added salt.

What is the pH of your tank? It's natural pH is most likely going to be fine for most livebearers and tetras.

What size tank is it?