I have an unknown number of red cherry shrimps in my 6 gallon tank. A 12 gallon tank would be perfect, if you get 10 you'll soon have a lot more than 10 (unless you get amanos which can't breed in fresh water)
I don't use a bubbler, just a small internal filter. But a sponge filter powered by an air pump would also be good, and that would also create bubbles as the air comes out of the filter.
If you want the shrimps to breed, don't keep fish with them. Newly hatched shrimps are tiny and make perfect fish food.
Red cherry shrimps are the hardiest and can live in a wide range of hardness & pH. Shrimps like the crystal shrimps are soft water shrimps and a lot more delicate. There are several colours of cherry shrimp - red, yellow, orange, blue and even chocolate and black. And in each colour there are shrimps if different intensity so bloody mary shrimps are a lot redder than red cherry shrimps, for example.
Sand or gravel, whichever you prefer.
Whatever plants you like suitable for the tank size. In mine I have java moss attached to a long thin piece of wood standing on its end so it's starting to look like a Christmas tree. I have anubias bonsai attached to a piece of wood, and Schismatoglottis preitoi planted in the substrate. I also have floating plants - at the moment I have half amazon frogbit and half red root floater. The shrimps like to graze on bits caught on the root hairs of the frogbit. I was intending to remove the frogbit as the red root floater grew but now I think I'll keep some.
Snails are fine, I have a nerite in with mine. Clams are notoriously difficult to keep alive as they are filter feeders and often starve to death.
You can do without a filter but I prefer to have one. Since baby shrimps are tiny they are easily sucked into filters so I have a fine mesh over the intake of mine. I mentioned sponge filters further up the post and they are ideal - baby shrimps can't get sucked in, and shrimps will eat bits of food caught in the sponge.
I don't have any other decor other than the wood and plants.
When doing a water change, you will suck up baby shrimps, and some not so small ones. I siphon the old water into a bucket then empty the bucket with a jug looking for shrimps in each jugful. When the shrimps were in a bigger tank (which I had to close down) my record was 32 shrimps in the bucket in one water change.
