umm...first welcome to MFK
fish can not be trained as dogs...and i definitely don't think ur jar can tell the difference in the food to be better or worse...they're all just food to him. i would understand if u feed the sliver more than u would for the jar, cuz well, the one gets more food will grow faster, thus more dominant.
and i don't believe that by tapping on the canopy has any effect other than just distract ur jar's attention, and startle him. being aggressive is just jar's nature. they're just that way, there's not a single or definitely factors that trigger them to be aggressive. so i don't think there's such a thing as the lucky one.
o, and about feeding live food, i used to think it makes a difference in their behavior, but i'm not so sure anymore. cuz i used to feed my jar feeder gold fishes for treat every now and then. but i've stopped feeding him live food for a long time since, however, i don't realli see any behavior changes. it'll still chases his tankmates around, ripping their fins, send their scales flying...etc. its behavior actually got worse i think, but i doubt that's due to the diet change, i think it's just got much bigger, and he's starting to feel cramped in my 85g.(moving him into 180g later). also, i've seen some big big jars in china, and they feed all live food over there. but their jars are kept in tanks w/tank mates, and they're doing ok.
as far as tank mates though, there's no definite answer, u'll just have to try ur luck, cuz every jar's personality is different. like my jar, it doesn't take interests in my bichir at all, but some ppl's jar would kill their bichirs...who knows, it all depends.
fish can not be trained as dogs...and i definitely don't think ur jar can tell the difference in the food to be better or worse...they're all just food to him. i would understand if u feed the sliver more than u would for the jar, cuz well, the one gets more food will grow faster, thus more dominant.
and i don't believe that by tapping on the canopy has any effect other than just distract ur jar's attention, and startle him. being aggressive is just jar's nature. they're just that way, there's not a single or definitely factors that trigger them to be aggressive. so i don't think there's such a thing as the lucky one.
o, and about feeding live food, i used to think it makes a difference in their behavior, but i'm not so sure anymore. cuz i used to feed my jar feeder gold fishes for treat every now and then. but i've stopped feeding him live food for a long time since, however, i don't realli see any behavior changes. it'll still chases his tankmates around, ripping their fins, send their scales flying...etc. its behavior actually got worse i think, but i doubt that's due to the diet change, i think it's just got much bigger, and he's starting to feel cramped in my 85g.(moving him into 180g later). also, i've seen some big big jars in china, and they feed all live food over there. but their jars are kept in tanks w/tank mates, and they're doing ok.
as far as tank mates though, there's no definite answer, u'll just have to try ur luck, cuz every jar's personality is different. like my jar, it doesn't take interests in my bichir at all, but some ppl's jar would kill their bichirs...who knows, it all depends.
..(although, the small indo picks on the RTGG sometimes 
)...so much for Jar's being "killers!" lol ...or maybe he's just a wussy? ...either way i couldnt be happier with the outcome...
(but, be sure you have an extra tank on the side just in case, for the wounded,lol) 
