Join Date: Nov 2012
Location: Melbourne, Australia
I'm no expert, but going by what I've seen in my own tanks, I'd say your tank is too small for the shrimp to effectively outrun the betta. Shrimp can move super fast when they need to, but if they have nowhere to run to, and nowhere to hide, I wouldn't like the chances of survival. This is speaking in terms of space alone, and not taking into account the issues presented by having tankmates in a space that small.
I'm sure someone more knowledgeable will reply, or perhaps has already by the time I've finished typing, heh.