Breeding Fish Tank Guides

Breeding Aggressive Fish

cichlid guides

Hints and tips for breeding aggressive fish

Common Issues When Breeding Aggressive Fish

If you keep aggressive species of fish and have a mix of male and female, then chances are at some point they are going to start breeding.  Many aggressive species, such as Cichlids, will readily breed in an aquarium.  Breeding aggressive fish can be very rewarding but it does come with problems.  Breeding can cause several issues in your aquarium because the aggression steps up a notch or two as part of the breeding ‘ritual’.

Firstly, the female within the pair may take the brunt of the punishment, male fish often get a little too rowdy, and it’s unfortunately not too uncommon for the female to end up dead.  This increased aggression also poses a three to any other inhabitants of the aquarium.  This will come from both male and female as they prepare an area for spawning, protect the eggs, and will continue as they protect the fry.

In the wild, there would be almost limitless space for fish to remove themselves from the situation if things get a bit too heated.  In your aquarium, they are essentially trapped in that environment with the aggressor.  So how can we protect the fish?


Protecting your fish while they breed

Protecting your fish while they breed is really important.  Firstly, for the welfare of the fish themselves.  As fish keepers, it’s our job to look after them and ensure they remain happy and healthy.  So that’s exactly what we need to ensure by preventing them from tearing each other apart.  Let’s face it, it isn’t going to help the look of your tank either or help your bank balance if you are losing a fish or two every two weeks when they breed.

There are several things you can do in your aquarium to prevent your fish causing each other injury, or worse, while they breed.  Which route you choose will likely be down to your set up and who is living in it.



Most aquarium set-ups include a cave or two for fish to hide in.  With some slight, very easy, modification these can become safe zones for your female.  In general with aggressive species, the female tends to be the smaller of the two.  If you provide a cave that only she can fit in to, then she will have a safe space to retreat to if the male is getting a bit too much.

There are several ways to achieve this.  The first is to simply set a cave up that is the right size.  How you create a cave for her is up to you, there are several materials to choose from, rock, wood, a pre-formed ornament.  As long as the female can fit inside and the male can’t, then it should work.

Another option when breeding aggressive fish is to use a terracotta plant pot, these are pretty commonly used in aquariums and aren’t difficult to come by.  They are easily modified to any size ‘entrance’ by piling up stones in the opening.  This makes it easy to adjust as your fish grow.  Just keep an eye on the male, if he tries to get in there he may get stuck.

If you opt for the ‘cave’ option when breeding aggressive fish, be mindful of any other fish in the aquarium, this will likely not help them too much unless you create multiple caves for each fish to hide in.


Hole in the divider

There are several tools that you might find useful when breeding aggressive fish. An aquarium divider can be really handy when fish are breeding.  These are seen pretty commonly and are usually made of crate (plastic squares).  With a crate divider, it can be used in the same way as a cave.  Cutting a hole to the size of the female fish means that she can pass through and the male cannot.  This means that the female can pass through the divider into a safe area of the aquarium where the male cannot follow, escaping any violence that may be directed at her.

This is a great way to keep your female safe, but you need to ensure the hole is cut to the correct size, otherwise, she may scratch herself up as she swims through.  Alternatively, if it is too big the male may fit through too, rendering your divider useless.  This method may not be useful to any other fish either, they will simply have to choose between been stuck with the breeding male, or the breeding female, both of whom will have elevated aggression levels.


Here’s a video showing the hole in the divider method in action:


Full Divider

Many people don’t realise but fish do not need to be able to touch each other to be able to breed.  So the safest option, when breeding aggressive fish, is to have a full divider, with no holes in it, to separate the male and the female.  Creating an area close to the divider, such as a piece of smooth slate, for example, will mean that the female can lay her eggs there.  The male, from the other side of the divider, can then pass his, lets call them ‘juices’, through which will be carried by the water to the eggs.

So far, this is your safest option for your fish, the female and male will be permanently separated so they cannot damage each other, but will still be able to breed.  Again though, this does no favours for any other fish in the aquarium.


The gold standard

I’m sure you can piece this together, but if you want to ensure the safety of your aggressive fish whilst they are in breeding mode, the breeding pair needs to be in their own tank, with a full divider.  In my experience, it is rare anyway that a community of aggressive fish of mixed-sex works very well.  I keep American Cichlids myself, which can be very aggressive, but I have carefully chosen them and they are all female.  This keeps aggression to a minimum and they are quite happy to live together.

If you are keeping mixed sex with the intent to breed them, then it works far better with only one pair in the tank.  Caves or Dividers can be added while the fish are breeding, removed when they’re not, or left in there permanently.  That is up to you.


Let us know any of your own tips for breeding aggressive fish in the comments!


Chiclasoma Bocourti

About the author

James @Seriously Fishy

I am a fish keeping enthusiast with over 20 years experience. I currently keep American Cichlids (CA) which are my favourite fish to keep so far. I started Seriously Fishy as I noticed a large volume of people on various web pages looking for help with Aquarium basics. I created the first Seriously Fishy book to solve the issue in 28 pages, that led to the Seriously Fishy UK fish forum and blog.

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