yeah walmart sold one to my brother in law and told him it would be find in freshwater also.
tang if your looking for something like the violet goby or dragonfish, there is a dinosaur eel (bichir) that petsmart has been selling for about 5$. i have one in with my oscars, i just made some caves that only he can get into and he is doing very well in there, i have another in my 29, he is always swiming around, he doesnt hide like most eels, he's really wild to watch.