im taking out all the river rocks today and iv got some stuff coming this afternoon that's ment to make rain water safe for fish , ill let you no its name ect when I get it , had 3 more looking sick yesterday all sitting on the bottom so iv taken then 3 out put into hospital tank they are still sitting on bottom but today they are still alive so hope they make it , and no there was nothing left in tank after salt water was used , when I got it ,it had leak so I had to fix that so tank was filled and refilled a few times so it had good wash out ,