i have one of those its about 6 inches long and is in freshwater, with 3 neons 6 angels 1 discus 1 golden algae eater and 2 cory cats. it eats frozen brine shrimp and flakes. my lfs said that they can live in brackish or fresh but will do best in brackish. don't put them in with anything aggressive, (i used to have 2) they are really peacefull and hide alot. they are really fun, and really pretty, i hear they can get up to about 22 inches long!