Can Saltwater Fish Be Converted To Freshwater

[hwoarangtag]

Can saltwater fish be converted to freshwater, while slowly adding less salt in the tank?

can fish adapt?

 

[DevUK]

Generally, no. Not that I'm aware of. Scientifically I believe (but not 100% sure) that salt water fish absorb salts and other minerals differently. There are of course brackish fish which live in lower salt environments, and then of course some fish that live out at sea and then return to fresh water to spawn (ie salmon).

Hopefully someone with more knowledge can help out here, but I would probably say as a general rule of thumb, no

 

[andywg]

I don't have the books with the papers to hand, but basically, very few can at all, and even fewer can do so for any real length of time and live a decent life. Many saltwater fish can survive extended periods down to a SG as low as 1.005, but below that rapid death is somewhat common.

There are some that can handle it, but as noted, these tend to be (or closely related to) euryhaline fish that live in different salinities of water throughout their life.

 

[jourdy288]

Mollies can live in total freshwater or marine conditions.

 

[kribensis12]

Yep

 

[Musho3210]

Mollies can live in total freshwater or marine conditions.

But remember, mollies arent saltwater fish, they are brackish

 

[kribensis12]

Scats can also switch back and forth( i think, i read it somewhere)

 

[natural blue nina]

I have a colleague who claims to have sucessfully introduced a clown fish (Nemo stylee) to her tropical freshwater tank. Admittedly this is the only survivor of three..... but it's been there for almost a year.

I have to say, I wholly disagree with what she is doing, and given that we are setting up a shared tank at work, I think I'm going to have to teach her alot about 'real' fishkeeping.

i just hope Nemo is happy!!!

 

[Bignose]

Mollies can live in total freshwater or marine conditions.

As this is the scientific subforum, can you please cite a source for this? Ok, not the freshwater part, but can you cite a source that demonstrates how much salinity a molly can survive in? Thanks.

 

[Squid]

I have a colleague who claims to have sucessfully introduced a clown fish (Nemo stylee) to her tropical freshwater tank. Admittedly this is the only survivor of three..... but it's been there for almost a year.

I have to say, I wholly disagree with what she is doing, and given that we are setting up a shared tank at work, I think I'm going to have to teach her alot about 'real' fishkeeping.

i just hope Nemo is happy!!!

Crikey... good luck with that one.

Why don't people just get tanks to suit the fish or vice versa.

Squid

 

[n3ont3tra]

Mollies can live in SW:
http/www.saltcorner.com/sections/zoo/mollies.htm
and there's this HUGE thread on reefcentral about people converting mollies to SW:
http/reefcentral.com/forums/showthread.p...mp;pagenumber=1

 

[Bignose]

Mollies can live in SW:
[URL="http/www.saltcorner.com/sections/zoo/mollies.htm"]http/www.saltcorner.com/sections/zoo/mollies.htm[/URL]
and there's this HUGE thread on reefcentral about people converting mollies to SW:
[URL="http/reefcentral.com/forums/showthread.p...mp;pagenumber=1"]http/reefcentral.com/forums/showthread.p...mp;pagenumber=1[/URL]

Can the native freshwater ones that will occasionally spend some time in brackish/marine environments live its full life in a marine environment? I was under the impression that mollies can survive out there, but that's not their preferred habitat and consequently wouldn't live anywhere near as long. That's why I was hoping to see some more scientific cites for these statements rather than a bunch of people's anecdotes. Don't get me wrong, I liked reading about some people's successes doing it, but what about long-term? Any cites on that? Thanks.

 

[n3ont3tra]

That's why I was hoping to see some more scientific cites for these statements rather than a bunch of people's anecdotes. Don't get me wrong, I liked reading about some people's successes doing it, but what about long-term? Any cites on that? Thanks.

Yeah, I thought that was what you were aiming for.
I haven't found anything on long term success, I think it's partially because of how much SW tanks have changed in the last few years. I'll keep looking though.

 

[jourdy288]

I don't remember where I read that, but total freshwater isn't good long-term, though. Sorry I didn't tell you earlier.

 

[nmonks]

Not sure precisely what you're after, but in terms of guppies, then the following papers are concerned with maintaining them in seawater rather than freshwater:

• Chervinski, J. (1984) Salinity tolerance of the guppy, Poecilia reticulata Peters. Journal of Fish Biology 24: 449-452.
• Shikano T, and Fujio Y. 1997. Successful propagation in seawater of the guppy Poecilia reticulata with reference to high salinity tolerance at birth. Fisheries Science 63: 573-575

As for mollies, I don't think there's any papers specifically about adapting them to seawater simply because they're found in seawater in the wild. So it's redundant. Sort of like writing a paper all about how penguins like the cold! Anyway, here's the Florida Museum's rather nice summary of the species. That Reef Central thread is funny. To think people didn't know you could keep mollies in seawater! Over here in England, it is absolutely standard practise to use black mollies to cycle marine tanks. Anyway, you can acclimate mollies from fresh to salt, or vice versa, in about an hour. Guppies takes a few weeks, maybe two months, if you want 100% success, and even then you need to be using wild-type guppies. The inbred fancy guppies don't do so well. Crossbred and feeder guppies are fine though. Endler guppies work, too.

Any old how. The list of freshwater fish that can live in the sea, and the list of seawater fish that can live in freshwater, is very long. We called them brackish water fish in the hobby. The problem is that hobbyists see fish as being either freshwater or seawater animals. In fact there is no "brick wall" separating them, and many fish can tolerate changes in salinity. Spend some time on Fishbase looking at entries for things like emperor snappers, dog-face puffers, clown triggers, green wolf eels, and orbicular batfish. All of those "marine" fish enter brackish water on a regular basis. Some, like the dog-face puffer, will actually inhabit freshwater for long periods and occasionally get traded as freshwater fish! Conversely, there are many cichlids, catfish, livebearers and killifish that routinely enter the sea. A recent (2007) discovery was that one of the species of iridescent shark catfish, Pangasius krempfi, enters the sea for part of its life cycle. If nothing else, this reminds us that the "catfish are allergic to salt" idea is complete rubbish!

Cheers, Neale