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Aquarium Fish Breeding: How to Set up a Spawning Tank

The author is a scientist and pet lover who has worked in conservation and woodland management over many years.

Guppies are the easiest fish in the world to breed.

Guppies are the easiest fish in the world to breed.

Breeder Fish

The easiest fish to breed are live-bearers. Fish like guppies, mollies and swordtails will get on with the business of breeding without much help. Egg-laying species tend to be more difficult. Some need sand to bury their eggs; others need plants or plant substitutes like bundles of green yarn as places to attach eggs.

This article takes a look at spawning tanks. These are helpful for many species and nowhere near as complex as you might imagine. Almost any tank can be converted to serve the purpose.

Reasons for Breeding Aquarium Fish

Before setting out on a fish breeding program, it is worth deciding what you are aiming for:

  • Are you interested in making some money? If so, how much?
  • Do you want to develop a new strain of a fish that you like?
  • Is it just an interesting challenge?

If you want to make a little money, the more space you have at your disposal, the better. A small back bedroom is a good place to start. An outdoor shed is fine if you can control the temperature. A similar space is probably needed if you want to breed a new line of fish.

The need to keep fish separate and prevent the wrong pairs breeding means you need quite a few tanks. A single tank will give you every opportunity to breed some new stock for yourself or to give as presents to friends.

Setting Up Your Spawning Tank

Size Recommendations

Either a ten- or twenty-gallon tank is a good size for a spawning setup unless you are handling very large fish. Too big a tank makes it difficult to monitor everything that is going on, and it is easy to lose track of spawners and fry.


A good lid is important because fish, in the excitement of breeding, can jump like crazy. For the same reason, be careful not to overfill the tank with water.

Aquarium plants

Aquarium plants


Decorations like stone formations and flower pots can be important as they give hiding places for fish. Some males will kill a strange female out of territorial impulses or simple bad nature.

Hiding places give the chance for fish to get used to each other before mating. They are also essential if you make the mistake of putting two males together. When nothing happens but a big fight, a hiding place will give you the chance to rescue the loser.

Advantages of Plants in a Spawning Tank

  • Both plastic and live plants provide privacy and reduce stress for your fish.
  • Some fish incorporate the plant material into their bubble nests.
  • Plants serve as spawning sites for many species of fish.
  • Living plants help to keep down algae by using up nutrients in the water.
  • Many fish benefit from plant material in their diet.
  • Plants help to create a more natural environment and encourage breeding.

Plants have differing temperature, pH and water hardness needs just as fish do, so it is helpful to discuss with suppliers which plants are best for your project

Substrate (Sand or Gravel in the Tank)

A lot of fish are very happy to breed in a tank with no gravel. The absence of gravel makes cleaning easier and monitoring of eggs and fry easier too.

Having said that, some species dig nests and these absolutely need a substrate so it is important to check on individual species' breeding requirements. A layer of fine sand is sometimes a good compromise. Fry don’t get lost or trapped so easily in sand.

Betta with bubble nest in a spawning tank.

Betta with bubble nest in a spawning tank.

Spawning Grates

These are a way of separating the spawning fish from their eggs or live offspring. While some fish actively care for their offspring, others won't discriminate between their own fry and a tasty blood worm.

A special spawning grate can be bought from a pet shop or some netting can be cut to fit the tank. As long as the eggs can fall through and the adult fish are kept out, that will do the trick.

Heaters, Filters and Pumps

Fry and eggs are more susceptible to water temperature and oxygen deficiencies than adults, so don’t be tempted to think small fish need less air or less care on the temperature front.

  • Water movement can help persuade some species to mate, but it is important to protect fry from powerful currents. In the worst-case scenario, all the fry in a tank might be driven into a corner where they stick together and suffocate.
  • Sponge filters will stop fry from being sucked into piping and will generally introduce less turbulence.
  • Coarse air stones can produce enough turbulence to damage eggs and fry and should be avoided.

Water Issues

pH, temperature and water hardness are always important in fish care but doubly so in spawning tanks. Sudden, even small, pH changes can injure or even kill fry.

Generally, whatever pH and water hardness requirements your adult fish have will suit the fry, so it is important to get good information on the species you want to breed.

  • If water temperatures soar above 85 degrees for any reason (strong sunlight on the tank, a noon-day shed, etc.), eggs will die.
  • If the temperatures are too high long-term, eggs can develop too quickly, resulting in deformed or spindly offspring.

Cleanliness and Nitrogen Levels

Nitrogen compounds from fish waste products are especially harmful to fry. It is usually worth changing about a quarter of the water in a spawning tank every day.

Feeding small amounts of live food rather than flakes that might go uneaten and rot helps with cleanliness. Many people remove any food that isn't eaten within a few minutes of being offered. Regular use of 'poop scoops' helps keep water clean.

Understanding Individual Species

A good spawning tank will increase your chances of breeding fish successfully. At the same time, it is essential to understand the needs of a particular species. For example, some fish are very social and need to be in large groups to feel unstressed. Other species are solitary. A good reference book will give you an idea of what each species needs to thrive.


Musa Mupiwa on March 02, 2020:

this is excellent

Hector Cortes on May 26, 2017:

I have. 55 gallon community tank. Fresh water.

I have angels and they have been laying eggs for about two years now.however, my pleco is enjoying sushi. I want to breed these angels just for fun. I have bread betas and rainbow fishes before with great success. I would love to try that with my angels. I want to set up a tank for a gold and black couple I have. Would this be worth it? And what would I need?

Will Apse (author) on July 27, 2010:

That sounds a good tip, caninecritics- nice and easy to clean too!

caninecrtitics from Massachusetts on July 26, 2010:

I like using marbles to separate the babies from aggressive fry eating parents. Especially Guppies since they like eating the babies.

expectus from Land Downunder on July 11, 2009:

nice hub sounds like fun I read this bit really quick "A good lid is important because fish, in the excitement of breeding, can jump like crazy. For the same reason be careful not to overfill the tank with water."

and took it as me getting excited and knocking the tank:P hehe

Will Apse (author) on June 09, 2009:

Sounds like the best tack, badcompany.

Will Apse (author) on June 07, 2009:

I'll look forward to that hub, Bard.

Steve Andrews from Lisbon, Portugal on June 07, 2009:

I have bred all sorts of tropical fish both as a boy and in later life and about 10 years back I joined the British Killifish Association and went on to have a lot of success with many species available by being a member. You have just given me an idea for a hub! Thanks for that and an interesting hub of your own!

Will Apse (author) on June 06, 2009:

Hats are good with fish. Why not write some fish hubs?