Male Molly Fish and Fry
Credit: Alana R

How to Start Breeding Tropical Fish

Should You Encourage Breeding in Your Aquarium?

One of the most exciting aspects of keeping tropical fish is breeding them and it is something that many fish owners become interested in at some stage, whether it occurs naturally or you have tried to breed your fish most owners at some stage will end up with fry in their tanks.

Many amature/hobby aquarium owners have gotten to the stage where they either want to try and breed some of their tropical fish or have awoken one morning to the surprise of finding tiny fry swimming around in their tank. No matter which type of owner you are, if you are interested in breeding tropical fish and want an overview of the best practices and methods to successfully breed your fish you need to do a little research.

While breeding can occur naturally, it is often unsuccessful for a number of reasons, firstly small fry are unlikely to survive without help, they get eaten by larger fish in community aquariums and quite often by their parents!  In fact it is not uncommon for the fish who is laying eggs to eat them as she lays them, so as you can see if you want to have any success you will need to help out a bit.


Breeding Tropical Fish Overview

Different fish will be easier to breed than others but there are some basics that you need to know first. Sexing fish can be difficult and working out if you have a male and female will take a little research.  In some species females are plumper and more colorful and in others it is the other way around. So it really depends on what fish you have in your tank, once you can establish that you have a pair you can attempt to breed them!

Bear in mind that you are going to need more space if you want to breed your fish and raise the fry. You can use a breeding trap for smaller fish, but you may need an additional smaller tank for larger fish and if you do breed your fish you can end up with hundreds of fry. You need to know what you can do with them or where you can put them when they start to grow!

Livebearers and Egg Layers

Some fish are live bearing, meaning that they do not lay eggs, instead they give birth to live baby fish or fry. Mollies and Guppies are Livebearers and are some of the easiest fish to breed. Fry are also less likely to being eaten as they can hide immediately so the survival rate is slightly higher than egg laying fish. Live bearing fish are also much easier to sex and you can easily tell by their fins. Male Livebearers have a gonopodium and females do not.

Breeding Molly FishCredit: Alana R

Many books will tell you that Livebearers will eat their fry however I have kept Molly fish for many years and had several batches of fry without using breeding nets or separating the parents from they fry without this happening. You can see in the image at the top of this article one of my male molly fish with his fry  It may look like he is about to have a snack but all he did everyday was swim around behind them as you can see in the image!

My Molly fry are alive and well and living in my community aquarium with other fish. To the right you can see them with the mother who is a white Molly. Dad is a dalmation Molly and so are all the fry. She had three sets of fry and you can see the first lot she had are much bigger than the third but they are all happy living together.

Fish that lay eggs take slightly more work, again you need to work out a male, female paring and have an area available to transfer them to. There are several different methods of tropical fish and they depend on the type of egg layer. 

Male Molly Fish

Breeding Molly Fish
Credit: Alana R

Common Types of Egg Laying Tropical Fish

There are  different types of layers that we will look at quickly below:

  • Egg Scatterers - Scatter their eggs which fall to the bottom or in some cases float to the top. Egg scattering species do not look after their brood and will eat their own eggs so breeding traps where they eggs can be separated from the parents will work best. Fry tend to hatch quickly and eggs are usually laid in large numbers
  • Depositors - there are two groups included in the egg depositor category, those that look after their eggs and those that don't.  Cichlids are an example of these.  They will look after the eggs and then fry and protect them.  The majority of depositors however do not care for their eggs but they rarely eat their own eggs.
  • Nest builders build a type of nest for their eggs and also care for their eggs and fry.

Breeding Fish in Traps

The basic practices are the same for most types of tropical fish, the male and female pair are best removed from the others whether you use a tank divider, breeding trap or net or a separate tank.

Once a Livebearer looks as if she may be ready (large and rounded) you should remove the male from the tank and ensure that the female has a good diet, she will then release the fry. A livebearing fish can have several batches of fry with out needing the male around as she can retain fertilized eggs for several months and release the fry periodically.

With egg scatterers and depositors that do not care for their eggs you should ensure that the area you have made available for breeding has a large substrate or marbles in the base which will allow the eggs to be hidden and avoid being eaten by the parents. Once the eggs have been laid you can remove the adult fish. 

The fry should be given a special diet and raised separate from the tank until they are at least a few days old before introducing them to other fish.

Although this can seem straightforward, it is not always easy to get fish to spawn, ideally to get healthy fry you should condition the parents ensuring they have a good diet and you should try and replicate the natural water conditions that the specific species are used to in their natural environment.

Breeding fish can be a lot of fun and is well worth learning how to do properly, successful breeding can be very rewarding and enjoyable but it takes practice, thankfully with the right conditions your fish will give you plenty of chances to learn!


Credit: Alana R

This is my female Molly fish with one of her fry. In total she had over 100 fry in three months and I have already given away over 50 of the more mature fry to other fish owners, the rest have been transferred to my biggest aquarium.

Raising fry does not have to be difficult and can be done easily in a community aquarium. We lost 2 fry (that I know of) at the beginning but the survival rate of the fry in my tank has been amazing! I don't use breeding traps and the only thing I do differently is add liquid fry food for the babies when they are young.