+1 PRC.
I have been on the "waiting list" for a pair of yellow multibanded pipe fish for 6 months now!! Everywhere online has been sold out forever. :(
The need a larger tank than a 20. They are long and skinny, so a 3' (at least) tank is important for them.
If you do decide to keep them (if you upgrade tanks or something), keep in mind they shouldn't be added to a new tank -- they really need a mature, established tank, because they are picky eaters.