How long can a fish remember previous tank?

[jonnybravo22]

I moved a fish into QT that was being aggressive to a new addition.

i'm hoping i can reintroduce him where he's the new guy and he wont be as aggressive (when i first introduced him he was quite shy, then b/c he was the only large fish roaming the tank began to think he owned the place).

so he's been in QT for 2 days. if i put him back in the tank do you think he will remember it and go right back to thinking it's his territory or will he be a bit more reserved now that there is another fish already comfortable in the tank when he is "introduced".


also how long do fish remember fish they have previously fought with?

 

[Gary Majchrzak]

the aggressor will always remember it's more passive tankmates.

rearranging the territory (rockwork) might help lessen belligerence.

 

[jonnybravo22]

grr that sucks. not what i was hoping to hear. but thanks for the response gary.

i'm trying a 3 pronged approach to this problem.

1. put him in QT to cool out for a few days and let the other guy establish some level of comfort in the tank (was hoping aggressor would forget the tank and think he was the new guy when introduced)
2. when i reintroduce i'm going to put aggressor in a containment box within the tank
3. when i let him out of the containment box i'm going to try the mirror trick -- taping mirror to the side of my tank so any aggressor will spend some of the time chasing his own reflection instead of the other fish

i now have 2 butterfly fish and 2 clowns which spend all their time in my gigantea anemone.

i really need a 3rd roaming fish to balance out the butterflies so they dont try to establish dominance but waiting for DD to get something else i want before i pull the trigger again

re: rockwork -- is it different to rearrange vs. removing the fish from it and putting him back. i guess one assumes he won't remember it and the other just says it has changed so he doesnt own it anymore. same rocks though so if the removing him doesnt work it would seem that rearranging wouldnt "trick him" into thinking he was in a new place, simply make it so that he hasnt "established" the new setup yet.

 

[Gary Majchrzak]

Chaetodonts establish a dominence by "ramming" or butting each other. It's rarely lethal and it's natural for them to establish a pecking order.
Some butterflies get along just fine. I don't think adding a 3rd fish will lessen the aggressions of the belligerent fish.

Personally, I had an aggressive Pyramid Butterfly that harrassed another Pyramid to the point of it not being able to eat. In this case it would be best to trade in the aggressor for another specimen.

 

[Wolverine]

the aggressor will always remember it's more passive tankmates.

rearranging the territory (rockwork) might help lessen belligerence.

I agree. IME, the rearranging, when it works at all, only delays the belligerence. Eventually, the dominant fish will usually reestablish its dominance in the new setting.

 

[treylane]

Well... again all fish/reefs are different, but I've used temporary-banishment successfully when introducing (initially-shy) centropyge angels into a tank with a sassy scopas tang. The tang was banished for ~4 days which was enough time for him to cool down and for the angels to get their bearings. When the tang was reintroduced he was a little bit skittish for a few days the angels were bold enough to hold their own against his wussy "attacks." 6 months of peace and counting...

 

[jonnybravo22]

a ray of hope! thanks for sharing your experience.

 

[Gary Majchrzak]

Well... again all fish/reefs are different, but I've used temporary-banishment successfully when introducing (initially-shy) centropyge angels into a tank with a sassy scopas tang. The tang was banished for ~4 days which was enough time for him to cool down and for the angels to get their bearings. When the tang was reintroduced he was a little bit skittish for a few days the angels were bold enough to hold their own against his wussy "attacks." 6 months of peace and counting...

I don't think anyone meant to imply that temporary banishment can't work. It can. But it's not going to change the ultimate outcome of who's going to be boss of the tank.
Centropyge should be able to escape Zebrasoma easily in rockwork (if necessary).
The Scopas didn't forget the Angelfish after 4 days but it's 'time out' allowed the Angelfish to adjust to their new surroundings.

 

[Korrine]

jonny, what species of fish is the bully?

 

[jonnybravo22]

update:

i removed the bully into QT for about a week and let the new guy get established a bit then added the original back while also taping a mirror to the back side of the tank and that combination really reduced the aggression. i noticed the mirror was a distraction to the aggressive fish (c. burgessi) at first. seems to be working well.

left the mirror on for about 2 weeks. now it's off and the one that used to get bullied even purposely swims near the other now. they swim together. at times there is a quick chase, usually during feeding, but seems to be getting less and less frequent and i'm no longer fearful for the health of the newbie (c. mitratus). food for thought!