Totally agreee, I think people are going a little hard on OP rn. Not that I think the idea will work, it almost certainly won't and I agree with Mr. Knightley and others that it seems you need more research. I'm really not trying to needle here, but your inability to spell (unless english is a second language, in which case I apologize) shows a certain lack of attention to detail that you will definitely need pursuing something this crazy.
However, your tetra idea is NUTS. They, like nearly 100% of freshwater fish, will tolerate a very low level of salinity (not just NaCl, other salts too). Guppies, and their kin platys, mollies, etc., are already physiologically adapted to handle brackish, like a mummichog, so the "experiment" to transition them wasn't much of an experiment.
I still say try it, but you definitely will not be getting a saltwater breeding tetra population in 5 years. Getting the fish to tolerate it is one thing - getting their eggs/fry to tolerate salt is totally different.
just don't use wild/endangered corals.... If you use cultured/tank raised corals I think people should save their ethical concerns for something more legitimate than a guy wasting his money