i got feeder guppies today, they are in a 5.5 gal tank under the cube that houses the eel. im feeding them brine shrimp which are in salt water, so with the brine comes a little bit of salt water, and im gonna keep them in brackish water and then feed the young ones to the eel as thay breed, hopefully this will work. but doesnt really matter if it doesnt because it only cost me $2 for 20 guppies.