FWIW, I have ethical issues of keeping organisms in greatly different conditions than they normally live in. We have no way to know if they are constantly suffering in the higher salinity.
Ooooh okay two things:
1. I think by now after 10 years in fish tank keeping I can see if a fish is thriving or not. My mollies in saltwater are in MUCH MUCH healthier, they are more active, they are more hungry, they are BIGGER, they live longer, and their FRY is born much BIGGER - all compared toi the mollies I keep in freshwater.
2. The explanation:
Mollies are EURYHALINE. Meaning they can live in both fresh, brack and sw. There is a lot of reasearch but starting with the basics for you from a QUICK search on wiki:
Euryhaline organisms are able to adapt to a wide range of
salinities. An example of a euryhaline
fish is the short-finned molly,
Poecilia sphenops, which can live in
fresh water,
brackish water, or
salt water.
The green crab (
Carcinus maenas) is an example of a euryhaline invertebrate that can live in salt and brackish water.
Euryhaline organisms are commonly found in habitats such as
estuaries and
tide pools where the salinity changes regularly.
However, some organisms are euryhaline because their
life cycle involves migration between freshwater and marine environments, as is the case with
salmon and
eels.
NOTE THIS: The opposite of euryhaline organisms are
stenohaline, which can only survive within a narrow range of salinities. Most freshwater organisms are stenohaline, and will die in seawater, and similarly most marine organisms are stenohaline, and cannot live in fresh water.
Partial list of euryhaline species
Some of these fish can't no longer live optimal lives in SW since they have been bread weaker and weaker and further from their natural roots over the years. Like the fancy guppy.
