Purpose of harming mate over a failed spawn?

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Omrit

Piranha
MFK Member
Nov 13, 2015
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I have seen many advise against removing fry/eggs from a cichlid pair because the male will sometimes hurt the female over the failed spawn. All that I have seen said about it in literature can be summed up to "The male will lash out at the female blaming her for the failure" as well as "If the female is larger it is the male that will instead be harmed". When talking with those who have had it happen it usually goes something like "Larger fish beat up smaller fish after fry/eggs were removed. Had to put in the divider for a while then they went back to being a pair".


I wonder what the use of this instinct is because it seems counter productive? Given that several different species are reported to do it I imagine it must serve some function.


Does anyone know how this scenario plays out in the wild? My hypothesis would be in the wild this behavior is to chase the failed mate away to possibly find a new one although that seems risky. I just can't think of anything else that would make sense unless this behavior is some byproduct of the unnaturally close quarters we keep them in.
 
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That's a good question.
I noticed that both partners show less aggression towards each other after a failed breeding attempt if there is more pressure from other fish in the tank.
In nature one of the biggest threads to eggs and fry is predation by other fish. So I would not be surprised if the natural reaction on loosing a spawn is more aggression to fend of predators.
A part of the explanation can be that there are not enough targets to disperse the aggression.

But I think that other things like testing the partners strength in some form of ritual fight like we can also see during pair bonding can play a role too. And in the small space of a tank these ritual fights can easily escalate.
 
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In nature the selection of mates is usually endless.
If a potential mate doesn't meet initial standards, it is (and has enough space) to be driven away.
And this is not the end of it.
Cichlids go thru a number of complex mating rituals to determine compatibility.
In aquariums we may house just a male and female together, or maybe 3 or 4 of a species together at mos,t to determine what becomes a compatible pair.
Its no wonder, that what we humans consider to be potential "pairs", often fail,
I usually try to get 8 to 12 of a species and allow them to determine mates among that group.
But compared to hundreds of potential mates in nature, its no wonder sometimes my pairings have not worked.
And its not only males that kill females, I have had females kill males.
And in nature if a spawn fails, there is enough space for the subordinate to get away relatively unharmed.
Because even in what are considered large tanks, a "clean getaway" is not really possible.
The Tomocichla tuba female below killed two males during mating rituals, before spawning with a 3rd.
But right after eggs were put down she killed him, yet successfully raised the spawn alone, you can see the line of wrigglers below her.
This is why many successful cichlid breeders use the incomplete divider method, that allows the smaller of the pair to escape, in the lack of space most tanks provide.
I find these go a long way to keeping both parts of a pair alive.
 
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Similar to what's been mentioned, I think-- when it does happen, because it's not universal to all species or pairs-- it's a matter of displaced aggression in a confined space and/or when the natural threats a bonded pair would normally cooperate to fend off are not present or not enough to occupy the pair. The behavior or outcome can vary by: species, sometimes by individual pair, and also circumstances in the tank. Since I usually breed fish in a community tank, and part of that is having species that can work a community in the first place, as well as achieving a compatible community, I typically haven't had much in the way of serious issues, including when a spawn is not successful (and I've bred many species).

In my experience breeding pairs are like marriages in the sense that some quickly bond well and have few issues, some fuss a lot or simply go through rocky spells, then may (or may not) settle into a cooperative pair, and some just don't work and you need to separate them.

So it pays to be observant of behavior, and since the needs and behavior vary between species it helps to know when a species has more specialized needs. For example, some species prefer a vertical spawning surface, some dig a pit, some spawn on a movable object like a leaf or shell, some want a cave or something resembling a cave, Cyphotilapia need an area protected from strong current, etc.

An example of success and a peaceful pair in an aggressive species if you give them suitable circumstances for their natural behavior, including other fish to protect the nest from:

 
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