There is no science stating that fish need to move to salt water at a certain stage in life, if they are eating great and living months like they are in your tank, as long as you don't do something to introduce disease or disrupt their current conditions, they should live long and happy.
At least we do know there is science saying there are strict freshwater population of these guys and the authors had caught eels of all sizes.
Also I will get a thread going of my group soon, so people can see them and how i have kept them.
