Yes, personalities and fish age, as well as whether they are trying to breed all will play into a tank dynamic.
A female Betta can be a good selection and there are some beauties too. One I had would scurry around "bossing" all the Guppies and other misc. fish which like to be around the top of the tank, and they all learned to mind her. She would often keep them away from her spot of the day, changed often, but then she would swim right along with them. Huge amount of personality there.
I also have had 2 types of Gourami together Pearl male and female Opaline, and then the same Pearl Male, he was a calm and peaceful one though with a male and later with one male Dwarf Gourami. They just avoided each other.
Clown loaches eat every snail around but get huge, about 10" to 1 foot.
Less feeding will help. Many fish always act like they are starving.