Adding a Tang led to my mated pair of Firefish divorcing

[GroktheCube]

Very odd, thought I'd share. I recently added a juvenile (<2") twinspot bristletooth tang (Ctenochaetus binotatus) to my 120g mixed reef that already had a well established pair of Helfrichi's Firefish and a Tailspot Blenny. I acquired the pair about 7 months ago from LA DD, and there has not been a hint aggression between them. They've swam together, eaten together, and slept together every night.

Two days after adding the tang, one of them started getting a little aggressive towards the other. I didn't look too bad, and the one getting picked on was giving submission signs (turned sideways shaking), so I didn't think much of it. Today, it's gotten to the point that the aggressor is really going after the other fish, and the one getting beaten up has torn fins and a few missing scales.

Has anyone had a similar experience? Given the reputation firefish have, I'm disinclined to take a "wait and see" attitude, but catching either of them is also proving to be very challenging.

 

[HumbleFish]

Yours is not the first post I've read on here about buying a "pair" of firefish from DD, and eventually they turn on each other. They were probably just two juveniles that got along, and now you've got two adults of the same sex. Odds are adding the tang was just a coincidence.

 

[GroktheCube]

They were both just about full grown when added, but it's not like a lot is known about their sexual maturation process. That's as likely an explanation as any. You're right that the appearance of a causative relationship doesn't mean that it's actually there, just seems like a pretty big coincidence.

 

[Ambition]

DD hasn't ever sold any mated pairs of fish that I know of... When they sell a "bonded pair" it only means the fish were collected together and tolerated each other in their tanks. Highly likely, that the addition of the tang is coincidental with the timing of the fish beginning to fight.