BNs can be aggressive killers?

[bekateen]

Hi all,

In an old thread (Re: Ancistrus sp. Albino X Albino Equals what?), I reported my male ABN trapping a smaller female in his cave and killing her. Speculation was that he wanted to spawn with her and she wasn't cooperative, then he got aggressive.

Sadly, it happened again, but this time the male was the victim. I awoke this morning to find my big female in the cave and the male wedged at the very back, his body crammed sideways in the cave (just like before). I worked his body out and found his belly opened up, again just like before.

This couple had spawned many times last year, to the point that I removed their cave to stop them. Only in the last couple of months had I replaced the cave, with a new one bigger than the old, so big as to not encourage spawning too much, but sufficiently small to allow the possibility.

How common is this lethal aggression?

[JamesFish]

Saw mine fight as female wasn't finished dropping eggs I guess and male had already in guard mode. They have taken some lumps out of each other.

I stepped in to split them tanks as they had taken so much damage any more would have meds and that was in just a few hours

[pleconut]

Hi Eric really sorry to have heard this news, as I mentioned I found with two males, this aggressive behaviour becoming such a problem in a 4 ft tank I rehomed one, I've not ever heard of females doing anything like this though. Of my pair, its always the male seeming to chase the female but quite aggressively, though its spawning related she usually escapes, my theory is when she is ready the will spawn. Maybe this could have happened, but his attempts to trap her may have been so persistent she hurt him escaping. The only time ever I've seen pleco aggression which led to deaths, and they were multiple, all within a few days of each other. Was when caves were much larger than they should have been. I believe it was most likely that as they were choosing the caves two had ended up inside one and fought very aggressively over it, i found them all with severly damaged fins. It was a large enough tank with no water quality problems whatsoever. But lots of cave aggression. I replaced the caves for a more suitable design and size, nowadays if there is conflict, it is one attempting to go into the cave but the occupant simply backs out slightly and stands its ground blocking the entrance. But Bristlenose plecos sometimes spawn in quite large spaces. So i can't give any more explainations to what happened.

[bekateen]

Now she just sits outside the cave as if she did nothing wrong...

[pleconut]

Was she gravid, my female a couple of weeks ago just after the first spawning was very skinny, was continually being chased she's very plump now, the male is much more relaxed it's just a matter of time, I'm sure she will go to him when she's ready to lay her eggs. Can you confirm if any eggs were actually laid. Just in the picture above the female doesn't look gravid.

[bekateen]

Yes, she's very gravid right now, but no eggs were laid. That's why I thought, wrongly, that they were spawning when I awoke this morning to find them both in the cave. And it was not unexpected, as i did a big water change yesterday, hoping to trigger a spawn. But when I noticed that it was the male inside and the female outside, I realized something was wrong.

This death was a surprise. The cave has been in the tank since December or November, and I've never observed any aggression between this mated pair. And then, out of the blue, I awake to discover this.

While I never want to get overrun again with too many baby BNs, I do enjoy watching the males with their freaky bristles, and I do like having some babies to sell - they are very popular at one LFS (which buys 20-30 at a time from me) and at my local aquarium society's monthly auctions. So ASAP I'm going to look around for another male, as close to size-matched as I can find, to meet this lady's companionship needs.

@JamesFish, yeah, I'm not surprised by male-on-female aggression in this species, but I am surprised by the sudden, lethal female-on-male aggression. One factor I'm also considering is size differential: This female has always been larger than this male. I don't recall their exact sizes. Last year's (at the height of spawning) SL measurements are in my BLOG. But in the last year, she has grown much faster than he. So that could very well be a factor.

[pleconut]

Where. I live it is difficult to source adults, if you can do so, I agree with you try to get one that is more of a match for her size. I like them too so even if get overun with fry I'd probably still keep my pair, although in separate tanks.

[JamesFish]

Sorry for late reply I'm surprised they killed. The female of my pair hunted my male round the tank when he was to small to sex had to use a divider to keep her away. Is it possible that only one side wanted to spawn or fighting over caves proved fatal?

Mine now live in separate tanks but my female still has a good inch length and a considerable bulk advantages on my male.

[pleconut]

What I've observed with my ABNs is in the last few days is this: I was really expecting them to spawn for the second time by now, my male and female are now both around the same size. But the amorous male has chased the female so much i think she that she is actually scared of him now, she's definitely gravid, I think is past being ready to lay eggs, I gave them a smaller cave than the one they had, but most of the time she's hiding, I presume from the male. But now i even have to move decor just to ensure that she's ok.

[smitty]

I always considered bristle nose to be aggressive. So it is no surprise to me.

[pleconut]

Like I said, I never seen females being aggressive, there's been some threads lately, reporting otherwise about aggressive females. However I personally witnessed two males becomimg very nasty with eachother, even in a 4ft tank, but one of them was in a cave on eggs before the fighting begun, so was probably just being protective