Mangrove Jack Struggling - advice

[William Mewbbb]

Hi Guys, Recently got a mangrove jack for my 266L tank, although he struggled at the start he had settled in well. but around 3 days ago i noticed him gasping a far bit, along with my barramundi that was also in the tank. unfortunately in the last 2 days, the two of them have both died.

Im not sure how or why however.
- The tank is fresh water
- i've been doing fortnightly 50/50 water changes
- have been feeding them jelly prawns and tiny mullet from the local salt water creek
- I havent checked the pH
- The gasping became less as i added an aerator
- Canister filter

Any reasoning behind the deaths or advice for future fish?

All fish were around the 5cm mark, and i also have two Australian Bass in the tank that dont seem to be struggling.
Thanks

 

[krichardson]

They both could have succumbed to parasites in their gills.

 

[Thyroyalgeek]

How do you get around so much krichardson, if you don't mind me asking? You post on practically every thread there is, lol.

 

[krichardson]

How do you get around so much krichardson, if you don't mind me asking? You post on practically every thread there is, lol.

Haha.....not hardly.You definitely will not see me weigh in on the flowerhorn and blood parrot threads.

 

[Thyroyalgeek]

Not a big fan for cichlids either, except maybe shell dwellers.

 

[Jabob56]

Was the jack wild caught? Could have introduced some sort of parcites or disease.