3 black female mollies avoiding single male avances, larger i believe female red eyed tetra agressive towards smaller i beleve male

Question
I recently purchased 10 gallon starter tank. Have several artificial plants, filter, gravel and decorative open seashell. stocked with 3 females and 1 male black molly, 2 red eyed tetras, 1male and female serpaie tetra and 1 male red velvet swagsword (the female died). 1 female molly was pregnant when I purchased her. She no longer looks pregnant and I see no frys. All of the females are avoiding the male's advances. WHATS WRONG.  Second, I have 2 red eyed tetras, 1 is larger than the other (told that larger was female and other was male - but not sure). She chases him constantly and he stays hidden in patch of bushy artifical plants (what to do)?

Answer
The aquarium is very overstocked and not properly stocked.

Tetra's, Swordtails, need 20 gallons.

Tetra's DO NOT school with other species of tetra's. The tetra's are picking on each other because they do not have the proper 6+ school.

Mollies need a 29 gallon as they get 4-5 inches in length, they are not beginner fish as they are more sensitive to water quality and they can be fin nippers and bullies.

Right now in the overstocked aquarium water parameters are unstable and eventually most of your fish will die off from overcrowding. You need to return/donate the fish as none of them are appropriate for your aquarium size.

Besides this you need the 1x male to 3x females ratio which you cannot have in that tank size.
All livebearers need this ratio as well as groups of 3.

In a small overstocked aquarium aggression is increased.

So if you had...

6x Serpa Tetras
6x Red Eye Tetras
3x Mollies
3x Swordtales

You will need a 30 gallon aquarium.

Please return this fish for the sake of their health they will not live long nor happy in that aquarium...

Here is a list of fish that CAN go in that aquarium size:

Guppies
Pgymy Cories
Scarlet Badis
Croaking Gourami
Shrimp
African Dwarf Frogs
Galaxy Rasbora
Harlquin Rasbora
Betta fish (with restricted tank mates)
Ember Tetra's