Mangrove Jack Fresh?

[greenterra]

They can be kept in fresh their entire life.True.. in the wild ,once they are true adults they generally go sea bound but many adults are still caught in brackish to freshwater rivers.As Theo said, they are like Barra.

My friends Jack


A couple of shots of the Jacks among the Barras in a freshwater display at Underwater world.These guys are quite large.

 

[Zoodiver]

Usually animals that move to salt as they mature are doing so to adapt to changing inside the body as they grow. Maintaining them in full fresh will work against the natural abilities to osmoregulate their internal salinities and lead to a shorter life span and more waste produced in the tank.
Same happens with sawfish, Atl rays, bull sharks, archers and other brackish fish.
I would also bet those "Freshwater displays" weren't true feshwater looking a other fish in them.

 

[happymidgetpaul]

So it's not a good idea then? Who has kept them successfully full fresh and for how long?

 

[greenterra]

I would also bet those "Freshwater displays" weren't true feshwater looking at the other fish in them.

It is the Australian freshwater display tank at Under Water World in Maloollaba in Qld, Aus.Every fish in there can be found in the fresh water stretches of our northern rivers and sometimes land locked waterways.


Mangrove Jacks have been kept successfully in fresh for many years. It is nothing new. It has been so successful that the Department of Primary Industries and Queensland fisheries started stocking a number of our Fresh water dams and impoundments with Mangrove Jack fingerlings several years a go. Catches 50cm and larger are reported often now and the Jacks are getting bigger.
See video of a Jack from one of our freshwater impoundments.

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[happymidgetpaul]

It is the Australian freshwater display tank at Under Water World in Maloollaba in Qld, Aus.Every fish in there can be found in the fresh water stretches of our northern rivers and sometimes land locked waterways.
View attachment 259869

Mangrove Jacks have been kept successfully in fresh for many years. It is nothing new. It has been so successful that the Department of Primary Industries and Queensland fisheries started stocking a number of our Fresh water dams and impoundments with Mangrove Jack fingerlings several years a go. Catches 50cm and larger are reported often now and the Jacks are getting bigger.
See video of a Jack from one of our freshwater impoundments.

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That's really cool, and after seeing that I think I might just go for it, really cool looking fish.

 

[Zoodiver]

It is the Australian freshwater display tank at Under Water World in Maloollaba in Qld, Aus.Every fish in there can be found in the fresh water stretches of our northern rivers and sometimes land locked waterways.

Agreed, but all of them can live in brackish as well, and some can live in full salt (like the microdon and jacks). I was just meaning often times aquariums will have a 'fresh' exhibit that is actually being run brackish to save on filtration cost.

 

[happymidgetpaul]

Agreed, but all of them can live in brackish as well, and some can live in full salt (like the microdon and jacks). I was just meaning often times aquariums will have a 'fresh' exhibit that is actually being run brackish to save on filtration cost.

Curious, why would brackish save on filtration cost?

 

[unstopable4700]

Usually animals that move to salt as they mature are doing so to adapt to changing inside the body as they grow. Maintaining them in full fresh will work against the natural abilities to osmoregulate their internal salinities and lead to a shorter life span and more waste produced in the tank.
Same happens with sawfish, Atl rays, bull sharks, archers and other brackish fish.
I would also bet those "Freshwater displays" weren't true feshwater looking a other fish in them.

this is why i think

 

[greenterra]

Agreed, but all of them can live in brackish as well, and some can live in full salt (like the microdon and jacks). I was just meaning often times aquariums will have a 'fresh' exhibit that is actually being run brackish to save on filtration cost.

Actually the Microdon is least likely to be found in a full salt environment. Of the 5 species found in Australia it is the only one classed as a freshwater variant and also Australias largest freshwater fish.

Extract from http://www.environment.gov.au/coasts/species/sharks/sawfish/index.html
[Species listed under the EPBC Act:
Freshwater sawfish (Pristis microdon)

Listed as Vulnerable under the EPBC Act
Occurs mostly in fresh or brackish rivers in northern Australia, sometimes more than 100km inland. Is not normally found in the sea off Australia.
Grows to at least 280cm
Biggest freshwater fish in Australia]


You are correct that the others can live in brackish and full salt.I am just trying to state that they can prosper in full fresh as well.I find it funny how people except keeping Barra in a Freshwater tanks but feel different when it comes to Jacks when they share much of the same habitat in our waters.The real issue is not whether to keep a Jack in freshwater for me but whether one can accommodate one for life as they attain such large sizes fairly quickly (50 - 55 cm in a few yrs)but this is my personal view on Barras as well.I see both for sale regularly here because the said owner/keeper can not accommodate its size anymore but that is another topic

 

[arvicanthis]

Hey HappymidgetPaul, The old mangrove jack can definitely be fresh all its life. It is a really adaptable species, there is no scientific evidence to support the belief that they have to spend their adult life in salt. if you have the space mate get it. they are just fab. if you wanna see a hobbyist with a complete fresh jack look at fugupuffs tank. He even has a completely fresh queensland grouper. E. Lanceolatus. Oh and it is lush!!

best of luck

arvi