Hello everyone. Here is the answer. We are all correct and incorrect in our understandings so the following links will make things clear as to what is really happening with these snails.
this is from page 10 of the link bellow:
The neritids are herbivores, feeding exclusively on algae and diatoms found growing on
rocks and other solid substrates. Neritids have an amphidromous life history, similar to
that of the fish. Eggs are deposited in freshwater, the young hatch, and are swept to the
ocean. After a marine larval stage, they return to freshwater to mature. Nerites deposit
their egg cases on solid substrates, including other nerites.
http/www.guamdawr.org/Conservation/gcwcs...%20Chapter3.pdf
here is a link to another site with photos of various Neritidae:
http/members.aol.com/Mkohl2/Neritidae.html
and here is another where it explains migration of freshwater snails.
Simply put, Nerites is a family name and there are many species. They do mate in freshwater, lay eggs in fresh water, eggs hatch in freshwater, babies are swept to the ocean where they develop from larvae to adults and migrate upstream again. Very much like the Salmon, and some shrimp species.
I believe that not all Nerites do this as some of you say that they can only mate in brackish water.
And Yes, I am 100% sure my snail is a Nerite and to be specific, it is Clypeolum latissimus (Orbigny, 1840) Rivers, Pacific side, Equador from the link (
http/members.aol.com/Mkohl2/Neritidae.html ) based on the photo provided.
This also explains why they never matured and I found most of them in my filter dead.
The Malaysian Trumpet snail that I have hasn't multipled. I may not be meeting its required conditions to reproduce.
I am aware of its ability to multiply fast but haven't seen that happen and it's been in my tank for almost a year. Still have one only.
Well everyone, we all learned something new. I certainly have and now I can say that I have more respect for the snail than ever before. There are certainly many types of snails out there and it shows we all have a lot to learn still. Learning is never ending. I drove my wife nuts with this research. I hope I haven't come across too strong on any of you. My apologies if I have.