Saltwater fish converted to freshwater?

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CarpCharacin

CarpCharacin

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Sep 20, 2014
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I have seen pictures of saltwater fish that have been converted to freshwater. It has been done with sharks, eels and other fish. There is not too much information about it and i read somewhere that it is not good for the fish. Is it bad for the fish? Why is it done? I didn't think that it could be done.
 
arent all rays saltwater converts? i think it changes how they process everything and they produce extra waste.
 
Technically if you go back thousands (maybe tens or hundreds of thousands) of years you can trace the freshwater ray ancestry to saltwater rays, but that wasn't an overnight salinity change that was a change from salt to fresh water over the corse of generations.

It all has to do with osmoregulation and 99% of saltwater fish aren't able to switch osmoregulation strategies. Fish that can convert from fresh to salt or vice versa only can because they have evolved for one reason or another to be able to switch their osmoregulation. You aren't getting things like tangs and angels and the like to live for too long in freshwater, nor can you get cichlids and tetras to live for too long in saltwater. There are some fish that can take varied salt levels but its not the norm and generally their tolerance range is limited to particular salinity levels (think brackish water fish) or are age dependent (scats and silver catsharks need increasing salinity levels as they mature).

Another thing to keep in mind when you see people do things on the internet. A lot of people just want a cool photo or video and don't really care or think about the longterm well being of the fish. So when it comes to outlandish stuff like that take it with like, an entire 50lb bag worth of salt.
 
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I think one wants to define what is meant by "saltwater" and "freshwater" fish:

1) fish that are born in and will never leave saltwater
2) fish that are born in and will never leave freshwater
3) fish that are born in freshwater and then intentionally migrate to saltwater
4) fish that are born in saltwater and then intentionally migrate to freshwater
5) fish that spend part or all of their lives in brackish water, sometimes migrating into fresh water of sea water.

My understanding is:

1) that almost all if not all fish in group 1 will die shortly after being placed in freshwater, while almost all fish in group 2 will die shortly after being placed in saltwater. Shortly could be a matter of minutes to days.

2) that fish in group 5 can survive for an extended period of time to varying degrees if given sufficient acclimation to pure saltwater or freshwater. Some brackish can't do that, while others can do so with success. It varies by species.

3) that people often are confused regarding fish in groups 3 and 4 with being 'always' all of one kind or the other. Depending on their age, these fish can indeed be in freshwater or saltwater. These are uncommon. Calling them "freshwater" or "saltwater" fish is imo a misnomer.

There are a few freshwater species (from group 2) that can seemingly be acclimated to saltwater. Much of this is species specific and typically relates to species that lived in water that was heavily mixed with saltwater within the last 10,000 or so years. This excludes most freshwater fish.

I don't recall any fish from group 1 that can be acclimated to freshwater.
 
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So are barramundi saltwater? I saw one for sale once and they said it was freshwater but it could be converted to saltwater if needed.
 
According to wiki, Barramundi are euryphaline (like the molly) so fit somewhere in group 3 or 5. They apparently can adapt because during their life cycle they intentionally swim into estuaries (brackish / sea water) where they spawn. Reportedly some spend their entire life in sea water where they have been cutoff from freshwater.

I've heard that people can adapt mollies to 100% sea water where they can survive just fine.
 
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neoprodigy neoprodigy once posted photos of a freshwater and saltwater cohabitation that he saw at a convention. Maybe clownfish and guppies? I can't recall. The vendor sold a special additive that make this "possible". You'll have to search through threads that are several years old, but maybe you can find the posts?
 
I call BS unless they were acclimated to a median salinity. Or just a money grab
 
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