The eels are relatively tough in taking handling after they have started to eat. They will get rid of the sand sticking to their protective mucus surface over their skin in the next hours and keep on growing. Do not use tab water directly, better collect rainwater or take water from a clean lake or river. The mortality-rates in tabwater of New Jersey is generally high. Don't be sad if occasionally an eel in your aquarium will die, this happens in the best nature too.
Sick eels turn white and fall on their side.
Transfer the dead eel into your mosquito farm, then the energy and nutrients will circle back into power of the surviving eels - via the phytoplankton and the grazers , like in the real world everywhere on our planet . Thank you all - we did make a difference , at least a small one.