View Full Version : Mangrove jack freshwater

06-10-2005, 03:03 PM
hey i was wondering if u can keep mangrove jack in fresh water
just because there is a topic that says about stocking Mangrove jack in brissy dams


06-10-2005, 08:16 PM
yep, if you want one a s a pet you can certainly keep them in fresh.

07-10-2005, 09:10 AM
so if i was to catch 1 in the nerang river would i beable to take it home in a live well and put it in a freshwater tank.
or would i have to adapt it
and if i had to adapt it how do u adapt fish

thanks 4 all help ;)

07-10-2005, 03:52 PM
shappas, converting fish takes quite a long time, had a mate who coverted a bream, took him ages. Every week or 2 gradually take the amount of saltwater out of the tank. Long process

07-10-2005, 05:45 PM
thanks mate

just another question does anyone know were in brissy or gold coast you can get bass barra mangrove jacks, perches cods etc, for Aquariums

07-10-2005, 06:21 PM
from aquarium shops or the wild?

07-10-2005, 07:55 PM
um preferably Aquarium shop
but um if u hav anyother ideas like a friends raises finglering

thanks mate

ps thats gold coast brissy

07-10-2005, 10:11 PM
yeh mate u can convert salt water fish to freshwater it just takes a long time. yeh nearly all your large pet shops sell these freshwater species so if u go down there im sure they can order them in for u. cheer ssteve

17-10-2005, 09:45 PM
Jacks the same as Barra will happily go straight from salt to fresh water, if they are caught in the wild they must be legal size.


27-02-2006, 12:33 PM
I have done jacks from salt to fresh in 10 hours before but the jacks were around 3-4 cm long the smaller they are the easyer it is but i know this works for jacks but i dont know about other fish

27-02-2006, 08:36 PM
I've taken jacks straight from salt water to a tank a few times & had 2 survive & 1 died. A good way to do it safely is to add a table spoon of non-iodised salt to the tank for every 5 litres. After a day chance a third of thw O2 with fresh & repeat every few days.
If you have other fish in the tanks, this dosage shouldnt harm them, even the small natives.
However putting a jack into a tank with other fish is going to see something die pretty soon.......... :-X



02-03-2006, 06:12 PM
I have had jacks in my tank. I converted them from salt to fresh in a couple of hours. I just kept changing half the water each half hour and replacing it with fresh, but these were small jacks (40mm). Make sure the water is aged and at the same temperature. You will find that with jacks, you can keep either one, or fifty, but not small numbers as they pick on the weakest and bite their fins until they are so damaged and the fish so stressed that it develops white spot and dies. Once that one dies, they start on the next and so on until only one is left. The small ones are pretty boring as aquarium fish as they just sit there around their "spot". All the best, Ray

22-03-2006, 09:31 PM
Here's a Jack for your tank ......... these little Jacks were DPI brood stock, stocked into Aplin's Weir Townsville last year.
Wonder how big they will get in the fresh?

Cheers Steve.

13-05-2006, 12:22 PM
guys at work we commonly swap barra jack and mullet between salt and freash water u can go from salt to fresh straight away for healthy fish but i would recomend at least 3 to 4hrs and over night is even better from fresh to salt is a different story although as a disease treatment swaping straight to onre from the other is a gr8 eco friendlily way of treating quite a few diseases with differing exposure times depending on species. But generally when going fom freash to salt 3 to 4 hrs change over time would be considered a minimum overnight would be the prefered option.

Just think in terms of what happens naturally ie . when it floods a creek or river will pretty quickly change salinity generally speaking anyway but when the flood subsides it generally takes quitea few tides to get back to normal with difering salinities up and down the length of the water course and also verticaly within the same section of the water course so the fish can migrate to an area of salinity that it preferes and take as much or as little time as it wants to change, however in a tank it has no choice it is at your mercy so to speak, so slowly with in reason is the usual method depending on time avalable.

For some species at least from my observations, bream for example other things also come into play such as water chemisty in particular water hardness bream do realy well in relatively hard freashwater but do not appear to do as well in soft freshwater probibly due to the inoic differences.

Hope this has been of some help and not too long winded


15-05-2006, 09:51 AM
Andrew, what sort've work do you do?

My mate has a big school of bream doing really well in pretty soft freshwater. He has a friend who converts fish from salt to fresh and has done it succesfuly with whiting and flathead also, I am getting him some moses perch soon to try to convert, as relatives of the jacks I'm hoping they should be able to adapt even if I have to keep it brackish it will be great in a big tank

15-05-2006, 11:23 AM
Hi Az,

I work at a marine fish hatchery, and have done for 10 yrs or so.


17-05-2006, 05:00 PM
Hi Guys,

Not many people seem to know that jacks actually spend most of their juvenile stages in freshwater. They stay in freshwater (when available) until they are big enough to move out into the estuary systems, then move offshore to breed.

They look very different when they are really small. Thet are usually a lot darker but have vertical white stripes down them, still got the classic jack shape though. There is a spot up near Mackay that has 100's of jacks up to about 40cm in purely freshwater, trapped in rock pools.

So you shouldn't have any problems with converting them to salt water but just take it slowly as Andrew suggested. Fish like this are classed as euryhaline - maenaing they are able to tolerate either fresh or salt water. There are many species that are like this including barra.


17-05-2006, 05:12 PM
Hi Az,

I work at a marine fish hatchery, and have done for 10 yrs or so.


good stuff mate, where is it based? Interesting work, would love to do something like that myself

03-06-2006, 04:33 PM

I work at the gladstone fish hatchery,