i have a 15 gallon freshwater tank with a filter.
i currently have 4 guppies (1 female, 3 males)
My female guppy recently gave birth to 7 babies, they are in a seperate tank at the moment but once they get bigger then i will be adding them into the tank as well
3 neon tetras (i had 3 others but they died :()
1 mystery snail
5 otos
5 cory cats

should i add 3 more neons
also, since the otos and corys are bottom level fish do they really count in the tank since all my other fish are top and middle level?

below is a pic of my tank setup

rule of thumb is 1 inch per gallon so 15g tank = 15 inchs of fish but that seems like alot of fish 4 that size tank , hope u have a BIG filter n do weekly water changes