[somewhatshocked]

Shrimp make up a tiiiiiny bioload.

You could fit a couple hundred in there with the supplied filter. Though, definitely replace it if/when you can with some sort of canister.

 

[somewhatshocked]

It's not necessary but it's nice. I run a small Eheim on my Ebi tanks and they're perfect.

Standard dual-sponge filters also do the job.

Because the Ebi is so small, it's often an issue of aesthetics, though, and they almost always look better without distractions in the tank.