How do I make brackish water for my new fiddler crabs?
It is fairly common practice to add a small amount of table salt to a fresh water aquarium, particularly for fish that prefer a brackish environment such as scats. May be a table spoon full or less to a small tank you might like to try this http://freshaquarium.about.com/cs/treatment/a/saltiinfresh.htm though the quantities sound very large to me. Taking a step back view, if I may. If the pet shop didn’t give you an advice, then sounds like a very poor quality shop to me and the quality of the stock may reflect that. The up side down swimming fish sounds as if it is in a bad way. Platties and fiddler crabs is not exactly a normal combination or a good beginners one. A responsible shop would have sold the tank, then a fish, then later you could choose some more over a couple of weeks. My advice would be to return the upside down fish. See what thrives and go from there. Start with
