Now this is the population that I have dwelling in my Self-made Nano-Fish-Tank. Even the cat approves:

6 x Red Neon:
PH:              5 – 7,5
Temp.:         24 – 30° C
Name:         Red Neon, (“Paracheirodon axelrodi”)
Origin:         South America, Columbia, Orinoco, Rio Negro
Remarks:    Flake food, Finely-cut living food, minimum of 6 in a herd
http://www.aqua4you.de/fischart1.html (german language only)

4 x Amano Shrimp:
PH:              6,3 – 8
Temp.:         23 – 27° C
Name:         Amano Shrimp, (“Caridina multidentata”)
Origin:         Japan, Taiwan
Remarks:    Omnivore, 4 recommended
https://www.garnelenhaus.de/garnelenhaus/amanogarnele (german language only)

2 x Piano Snail (“Eloise” & “Mathilde”):
PH:              6 – 7,5 
Temp.:         22 – 28 °C
Name:         Piano Snail, (“Taia naticoides”)
Origin:         South-East-Asia: Burma, Vietnam, India
Remarks:    Dust food, Sand to dig in
http://crustahunter.com/taia-naticoides-theobald-1865/ (german language only)