Paring Mandarin & Aggression

[astrofish]

Hey guys, I've been having a hard time pairing mandarins and wondering if anyone has experienced something similar.

I have both spotted and blue mandarins, male and female, and I've noticed the same pattern several times. When I first introduce them, they're usually fine for the first few days and sometimes even look like they're pairing up. Then after a few days or a week, one suddenly starts chasing the other pretty aggressively.

With my blue mandarins, I had a male that stayed together with a female for about a week, then suddenly started chasing and nipping her fins. She eventually died, most likely from stress. He then started doing the same thing to another female, so I separated them.

I've seen similar behavior with spotted mandarins too. It's not always the male either. I've had a larger female attack a smaller male before.

Right now I have a larger male spotted mandarin with a slightly smaller female. The female was already established in the tank. First day they were fine and I even saw what looked like some courting behavior, but the next day the female started chasing the male whenever she saw him.

The weird thing is, if I put both of them together in a small isolation box, the aggression completely stops. There's no divider between them, but they don't fight at all. Put them back in the display and eventually the chasing starts again.

I've seen this happen more than once now, so I'm really curious what's going on. Has anyone experienced this with mandarins? How did you successfully get yours to pair?

 

[exnisstech]

I've only paired them once. I had an established female and added a smaller male. She tossed him around a few times then they figured it out. I never saw aggression from the male, maybe because the female was considerably my larger?

 

[DaJMasta]

I've paired them a few times and never really run into issues - there is some initial aggression that can be largely defeated by a clear plastic introduction box and then the subsequent chasing, to my understanding, is normal courtship/territoriality behavior, I've seen several males do the same (though my current one didn't, he and his mate were both a little smaller than the average wild caught fish and approximately the same sized, introduced at the same time.)

What's the tank like? Do you have enough coral/rockwork to easily break line of sight in a chase? How often are you feeding and what?

In my experience some amount of nipping is reasonably common, but it surprised me a couple times how intense the chase was - to the point that separating them after that could be useful (I never had, though.)

 

[astrofish]

I've only paired them once. I had an established female and added a smaller male. She tossed him around a few times then they figured it out. I never saw aggression from the male, maybe because the female was considerably my larger?

I had a smaller male who got bullied by two females (larger than him). So I took out the both females, and let him settle in the tank alone for a while and I re-inteoduced one of females a few weeks after, and then he started chasing her very aggressively, nipping too. So I took her out and tried with nother female, it happened again. So I let him live alone for a week and reintroduced one of females again, and next day my male vanished completley. My female might have killed him

 

[astrofish]

I've paired them a few times and never really run into issues - there is some initial aggression that can be largely defeated by a clear plastic introduction box and then the subsequent chasing, to my understanding, is normal courtship/territoriality behavior, I've seen several males do the same (though my current one didn't, he and his mate were both a little smaller than the average wild caught fish and approximately the same sized, introduced at the same time.)

What's the tank like? Do you have enough coral/rockwork to easily break line of sight in a chase? How often are you feeding and what?

In my experience some amount of nipping is reasonably common, but it surprised me a couple times how intense the chase was - to the point that separating them after that could be useful (I never had, though.)

Wow, I guess you got lucky! My tank is about 40 gallons with heavy rockwork and a refugium. My mandarins also eat pellets, so food isn't really an issue. The problem is that once they get stressed, they start eating less and getting skinny.

How long did the constant chasing and fin nipping usually last for yours? I always end up separating mine within a week because one of them starts looking really stressed or gets damaged fins.

I've had the male in an acclimation box inside the tank for two days now, and I can see the female coming up to the box and trying to nip at him pretty often. Yesterday I tried releasing him back into the tank, but the constant chasing started again. The male was trying to get away from her and eventually stayed near the surface.

The biggest mystery to me is that as soon as I put them together in a small acclimation box, there's no chasing or fin nipping at all. They're completely peaceful, like there was never any hostility between them. I really don't understand why that changes so much in the main tank.

 

[DaJMasta]

Maybe that's a distinction I didn't make - my pairs were never constantly chasing. They would largely do their own thing during the day and the chasing, sometimes seeming somewhat aggressive, would begin around dusk in the tank. I had a larger female who was established in the tank that acted very territorial and aggressive to the introduced male in the box, but she had basically lost interest in him after like 6 hours, so I let him out that day. I think there was a little more squabbling, but nothing appearing specifically alarming.

Maybe as a result of the less aggression I'm seeing, I haven't seen a decline in one eating or another, but as my tank is also about 40 gallons, I train them onto frozen in breeder baskets before even introducing to the main display.

Maybe it would be worth isolating the existing fish and then letting the new one sort of lay claim to the tank before reintroducing the established fish? Maybe the mirror trick for tangs would help with mandarins? I definitely see mine trying to keep their reflection in the glass off their turf.

Since they're eating pellets, are they adult, wild caught mandarins? Maybe there's some difference in introducing the younger captive bred ones.