i recently got one for the first time, (about 2-3 months ago) and have never seen as much "punch per inch" in a fish.
now hes about 3/3.5 inch and is a wrecking ball. he used to beat up on the barramundi when i first put him in. (when the barra was eating bronze goldfish bigger than the jack). but now they get along except for thieving food from each other.
in my tank I've got two big solid rocks that the jack uses to "tenderize" his prey. he simply grabs the goldfish, usually by the head. and then takes it straight down the other end to pulverize the fish into edible chunks. on the rocks, as your jack was trying to do so on the gravel substrate of your tank. i think your jack would appreciate some big rocks to do the same and it sure makes for some sickening maiming of goldfish. especially with smaller fish cleaning up the scraps, like my archerfish do.
awesome fish you've got, he looks at home and healthy. nice
now hes about 3/3.5 inch and is a wrecking ball. he used to beat up on the barramundi when i first put him in. (when the barra was eating bronze goldfish bigger than the jack). but now they get along except for thieving food from each other.
in my tank I've got two big solid rocks that the jack uses to "tenderize" his prey. he simply grabs the goldfish, usually by the head. and then takes it straight down the other end to pulverize the fish into edible chunks. on the rocks, as your jack was trying to do so on the gravel substrate of your tank. i think your jack would appreciate some big rocks to do the same and it sure makes for some sickening maiming of goldfish. especially with smaller fish cleaning up the scraps, like my archerfish do.
awesome fish you've got, he looks at home and healthy. nice