Can I add neon tetras

[aaw1218]

I have a 20g long tank with 55 gal filter and currently do 20 percent water changes weekly

Stocking:
4 Red eyed Tetra
1 Neon Tetra
1 Gold ram
1 Dwarf Gourami

Can I add some more neons?

 

[mambee]

Most definitely. Your tank is not overstocked, and neons need to be kept in schools.

 

[Barliman]

Can I add some more neons?

Easily. You can add six more for a school of seven with no problem, I think. With that many neons, you'll start seeing more interesting behavior, too.