Well in there natural habitat they live in rice patties which has no current. And in my tanks i never see them sitting in front of the filter current. So if you already have the filter put it on and judge yourself if there is too much current, but make sure there are some slow current spots or else you will prolly just see him sitting there all the time. So if its just a 2 gallon tank i dont really think it needs a filter, well maybe a sponge but nothing is gunna beat water changes in that 2 gallon. Good luck!
- depthC