How Long to Reset Fish Agression

[Zakary2003]

I have a 6 lined wrasse who I suspect is behind the death of my latest three fish additions. He was added about 8 months ago, and was the last fish that survived being added to my tank. Since his addition, I've tried to add a yasha goby and two banggai cardinalfish. The yasha disapeared entirely, the first banggai was found in a powerhead, and the second banggai was found with his fins ripped apart. I managed to capture the wrasse and I am getting a replacement pair of banggais today, but I want to know if it's possible to reset the wrasse's aggression.

He is currently in an acrylic breeder box floating in the tank. I can either leave him there or move him to my brother's tank for a little while, but I'd prefer to keep him in the my tank. If I leave him in the box, will he eventually get over the new additions and lose his aggression? If that wouldn't work, would removing him from the system entirely work better? In either scenario, how long would it take to curb his aggression if it's possible at all?

I love the wrasse, and I don't want to replace him or return him to the fish store. He takes food from my fingers and comes up to the tank to greet me when I walk into the room. Catching him was as easy dipping the acclimatoon box in and wiggling my fingers inside. I know I made a mistake adding him before the rest of the tank stocking, but I really want to fix him. He's never bothered the clowns that went into the tank first, and I've never seen him attack the new fish, but I don't know what else could have destroyed the second banggai like that.

Any other recommendations are welcome!

 

[Mr. Mojo Rising]

You can rearrange the rocks and add the other fish then the wrasse last, that might work or not. But tank size has a lot to do with aggression, what size is the tank?

 

[Zakary2003]

You can rearrange the rocks and add the other fish then the wrasse last, that might work or not. But tank size has a lot to do with aggression, what size is the tank?

It's a 20 gallon. Small for an adult 6 line, but he's an especially tiny specimen. He was about 1/4 inch when we got him, small enough to fit into the overflow cutouts. We were going move him to my dad's 60 gallon when he's big enough to not get eaten by his fish but he just had so much character in the small tank that I didn't think would carry in to a larger system, so I'm not sure that's still the plan.

 

[sfin52]

I've removed a half black for six months put back in system and he went right back to being a terror. Some fish won't change.

 

[Doctorgori]

you trying to “ rehab” a violent criminal?
I dunno personally I never allow those kind in my lilly blue reef hoods … 6 lines are violent and when they move in they bring reef values down
suggest rehome to your enemies

 

[ajmckay]

In similar situations I've tried various things like rearranging rocks, housing the aggressor/victim in a floating basket, etc... but somehow the aggression persists in pretty much every case.

So I'd say 2-3 days of "time out" even with changing the scape around. If you're dead set maybe try a week? I think it also really helps to make sure the new inhabitant is eating really well and has recovered some after transport. Good luck!