Strange Aggression

[Labridaedicted]

Hey gang! Weird issue I have encountered the past few days...

My tang (Ctenochaetus flavicauda) has been in my tank for close to 2 months now with minimal aggression. The only other broad bodied fish in the tank is a yellow blotch rabbitfish and he is not aggressive at all towards him. In the past week, however, he has began bullying my male Lineatus Wrasse and my Watchman Goby to the point I don't see the goby much and the wrasse is hiding at the top corner near the overflow box.

I feed 5 or 6 times a day and they get a full sheet of nori every other day, so I don't think it's a feeding issue. What would cause a tang to suddenly change behavior like this and go after fish that clearly aren't direct competitors? I would have expected aggression towards the rabbit, if anything...

Anyone else had a similar experience?

 

[eatbreakfast]

I've had Ctenochaetus tangs be problematic to wrasses as well. Don't know the reason why, but it had to result in the bristletooths being removed.

 

[Labridaedicted]

I've had Ctenochaetus tangs be problematic to wrasses as well. Don't know the reason why, but it had to result in the bristletooths being removed.

Oddly, he doesn't bother the pintail or the McCoskers. Just the lineatus. Hopefully it doesn't come to removal since he's my favorite non-wrasse in the tank. :-/

 

[Andy G]

Aggression can start in 2 or 3 weeks after the tang was introduced. It happened to me before, the firsts 2 weeks is fine and then starts bullying.

 

[Labridaedicted]

Yeah, it was just odd that it took this long to see the aggression. Also weird that it's only with wrasses as opposed to grazing competitors. Although he and the rabbitfish have had a few tussles and they both had the scratches and cuts to show for it. Now they cruise together. The Pintail finally came out of hiding after introduction and now occupies the other side of that overflow box... so that is currently a very expensively decorated overflow box right now with a male lineatus and pin tail adorning it....

Anything you guys can think of to try before I just outright pull the tang? And banish him to the frag tank? He is my favorite non labrid in the display and would like to try to keep him. I'm getting ready to order my harem of 7 lyretail anthias, maybe that will distract him some?

Also worth noting, he shows positively zero interest in the McCoskers who has actually become quite bold (out of character for a McCoskers ime).

 

[eatbreakfast]

You can try distracting it with the anthias, but I'm betting he will have to be caught and removed.

You could try trading it for another specimen and maybe the new specimen won't be as aggressive.

 

[Eva Rose]

My whitetail bristletooth was good for 2 years. Then it starting bullying my midas blenny it had previously ignored. I tried changing aquascape, and ordered a fish trap to be prepared (as R2R members advised). It stopped bullying for a few days then as you have described -- it got very belligerent. That morning the sporadic chasing went to aggression towards many fish - blenny, hawk etc.
Fish Trap
I used the fish trap immediately. My terrorized fish went into the trap first. So I placed them in the sump for a few hours to rest. I observed the bristletooth & it was not food motivated to enter the trap (since it can just pick off rocks). It kept swimming looking for those fish (safe in sump) to bully.
I then put fish from the sump into a social acclimation box. I placed the acc box in the front corner of the tank so it was touching the end of the fish trap box. This way the tang was motivated to reach the fish by entering the trap.
Then I let the tang enter the trap 2 or 3 times and just kept still. Once it entered again & focused on the fish (safe in the acc box) I sprung the trap. My tang has now been rehomed.
I would use a fish trap and a mirror.
Position the mirror so the tang will enter the trap (to attack its reflection).


I loved the beauty of my whitetail bristletooth. But went it showed aggression it escalated rapidly in intensity. Definitely get a fish trap. You can always use it as a social acc box. They are multipurpose tools.
Good Luck

 

[stevo01]

I would also put a mirror up for at least a few weeks.

 

[Labridaedicted]

Just as an update, I managed to catch him and he's going to be in the frag tank for a while. I might sell him since, as much as I like him, my wrasses are priority. As soon as I pulled him, both wrasses and the the goby started coming back out again.