they are brackish but can do fine in freshwater also. the bigger problem is that most people dont cater to the various other needs they require. they are shy, poor eyesight, require fine substrate to dig and do not compete for food. naturally they sift through mud and sand for small food items. they like to dig themselves burrows and my success only came from target feeding in the burrow where other fish could not steal the food. best suited for a species tank designed around their needs ie you might as well give them dim light, sand and a light brackish water. coming from coastal areas, their natural environments salinity fluctuates regularly