I've had a non-CO2 20G tank for about a month now. It has 19 Galaxy Rasboras in it with one red cherry shrimp (RCS). Other than small amounts of thread algae, there is no algae whatsoever. The thread algae is very easy to remove every few days, so it's not a big deal.
My question: What are some of the best thread algae eaters that would get along well with Galaxies? I would prefer an algae eater that didn't eat the Galaxies' eggs. I've had SAEs in the past, but they seem to grow a little too big for a 20G. I've also had SAEs get pretty mean in the past, but I think that was because I was feeding them wafers, which gave them something to guard/protect.
I've heard that RCS eat thread algae, but haven't witnessed it myself so far.