How to Breed Fish

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Breed fish in your aquarium and raise new fry with our guide
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Breeding fish in a home aquarium isn’t as easy as simply sticking a male and female of the same species together and hoping for the best—it requires careful preparation and monitoring. After you’ve researched the specific mating habits and preferred living conditions of the species you’re trying to propagate, your first step will be to select a healthy parent candidate of each sex. You’ll then need to carefully engineer key tank conditions like water temperature, pH level, lighting, and surrounding flora to make them more favorable for mating. These environmental changes help “set the mood” for the parent fish and ensure a successful coupling.

How to Mate Fish

To start breeding fish, move a male and female to a separate tank and feed them a nutrient-rich diet. Give them plants, rocks, hiding places, and sprinkling water to make a safe space for the fish to breed. After your fish lay eggs, move the parents back to their original tank.

Part 1
Part 1 of 3:

Selecting the Parent Fish

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  1. In order to breed fish, your first step is to determine their biological sex. Unlike some other animals, this will be trickier than looking for differences in their genitalia. The biological differences between species can vary greatly, but there are a few common traits to look for. Female Cichlids, for example, tend to have rounded bodies and less pronounced vents, while males usually display more vibrant coloration and sometimes have a small hump on their heads.
    • Make sure you only breed fish of the same species. While it may be possible for two different species to reproduce, there’s a good chance that the resulting hybrid will be feeble, deformed, or sterile.
    • Pass over fish that appear sick, injured, or deformed. They’re less likely to produce healthy offspring. [1]
    • If you're at a loss for how to differentiate the sex of your fish, take them to an aquatic veterinarian or breeding specialist to have them examined by an expert.
  2. This tank is often known as a “spawning tank.” Isolating the parent fish in a spawning tank shrinks the mating pool to 2, making them more likely to couple than they may be otherwise. It also allows you to tinker with the conditions inside the tank without being disruptive to a larger colony of non-mating fish. [2]
    • For most species of fish, you’ll need a spawning tank with a capacity of at least 5–10 gallons (19–38 l).
    • When you first transplant the parent fish to a new tank, it's best to keep the conditions as close to their old tank as possible and make necessary adjustments very gradually to help them get acclimated .
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  3. Feed the parent fish a nutrient-rich, high protein diet while you’re encouraging them to mate. Proper nutrition will help them flourish and increase their fertility. Remember: the healthier the parents are, the healthier the babies will be. [3]
    • Most average-sized aquarium species like Bettas and Angelfish prefer a live diet of fresh or frozen brine shrimp, white worms, or daphnia. [4]
    • It’s best to condition fish for roughly 2 weeks before they begin mating.
    • Learn about your parent species’ natural diet to know what sorts of foods you should be feeding them in the early phases of breeding. Most fish do best with a balance of fresh herbaceous plants, as well as live offering like brine shrimp. [5]
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Part 2
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Creating Favorable Mating Conditions

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  1. Before you attempt to put 2 fish of the opposite sex together, make an effort to learn about their instinctive reproductive behaviors. Knowing what a particular species looks for in a mate and how they lay their eggs, as well as the exact manner in which they copulate, will allow you to closely mimic breeding conditions in the wild.
    • Read up on your species in a fish encyclopedia. You may also be able to find books and manuals that delve deeper into the specifics of aquarium breeding.
  2. . Apply your newfound knowledge of your parent species to make their surroundings more hospitable. Factors like temperature and the chemical and mineral balance of water can influence whether or not fish decide to mate. It may be necessary to use a separate heating element to warm the tank or soften the water to change its basic composition.
    • In order for Discus and related species to begin breeding, the water in the tank must be brought to between 82–88 °F (28–31 °C), with a pH level of 6-7 and moderate to low light. [6]
    • Goldfish breed in spring. Lower the water temperature to 52 °F (11 °C). Then, when you are ready to breed them, gradually raise it 3 °F (1.7 °C) per day until it reaches 72 °F (22 °C).
    • If you have to make a significant adjustment to the water in the spawning tank, do it little by little. Water temperature, for instance, should only be raised or lowered 3-5 degrees over the course of about a week. Too drastic a change in too short a time may agitate or even harm the parent fish. [7]
  3. This is when most fish begin to breed in the highest numbers. Use a watering can or circulating sprayer system to create the effect of a light downpour on the surface of the water. Changing the water level by draining the tank halfway and slowly refilling it can also trick fish into thinking that it’s the ideal time to fertilize and lay eggs. [8]
    • When you first lower the water level in the tank, leave it shallow for a few days so that the fish have time to get used to the difference. Then, gradually return the water to its original level over the course of about a week, using water that’s 2–3 °F (−17 – −16 °C) cooler than what’s already in the tank. [9]
    • For a more convincing simulation, try dimming the lights in the room and switching a flashlight on and off near the tank to make “lightning.”
  4. Add elements like stones, plants, and artificial tunnel structures to the tank to approximate the natural conditions under which the parent fish prefer to mate. Cichlids, for example, typically mate on flat rocks, while other species retreat to the safety of caves or drift closer to the surface of the water . A more recognizable environment will put them at ease and prompt them to increase their numbers. [10]
  5. If necessary, switch out the filter you currently have in your spawning tank for one with less suction. High-speed filters may over-circulate the water, creating strong currents that can sweep away tiny eggs or even suck them up. [12]
    • Sponge filters are typically recommended for aquarium breeding.
    • Using a less powerful filter may make it necessary to clean or replace the water in the tank more frequently (up to 15-20% of the total volume every 1-2 weeks, depending on how murky it is).
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Part 3
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Protecting and Caring for the Fry

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  1. Once the female has laid her eggs or given live birth, return both parents to their original tank, where they will quickly acclimate to their ordinary environmental conditions. This will protect the eggs from being interfered with long enough for the fry (newborn fish) to hatch. Keep the conditions in the tank the same. It can now be used as a nursery tank to rear the fry. [13]
    • With the exception of a few nurturing species, it’s not uncommon for adult fish to devour their own eggs.
    • If it’s not possible to set up a different tank for the fry, add an abundance of plants and other physical structures to give them a place to hide once they’re capable of swimming. [14]
  2. Cover the tank on 3 sides with paper or scraps of fabric thick enough to block out most of the light from outside. Eggs and newly-hatched fish are often sensitive to light—too much may stunt their development or even kill them. As they continue to grow, their tolerance will increase and you can return the aquarium to its original light levels.
    • Be sure to black out the sides that receive the most direct light exposure. Leave one of the larger sides uncovered for observation.
    • You can even leave the tank completely covered with a sheet when you’re not feeding or checking on the fry.
  3. . Get in the habit of emptying the tank by 25-50% and replacing it with fresh water at the same time each day. Clean water is a must while the fry are learning to breathe and filter on their own. [15]
    • Draw from the same source every time you refill the tank. It’s important that the new water have the same basic composition as the old.
  4. When the fry first hatch, they come equipped with a large yellow egg sac that provides sustenance for a few days. Once this egg sac disappears, you’ll need to begin feeding them yourself. Liquid egg yolks, crushed fish flakes, plankton and algae are all examples of foods used to nourish fry.
    • Look for the foods and supplements you need at pet stores that sell specialty fish supplies. As always, do your homework to find out what foods are suitable for the fry of the species you’ve selected for breeding.
    • Smaller species like tetras and rainbowfish, for example, won't be able to handle commercially prepared foods so soon after hatching, and need to be fed liquid infusoria or similar supplements that they can digest easily.
    • As the fry grow larger, they can graduate to more substantial live foods like brine shrimp and microworms.
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Community Q&A

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  • Question
    What should I do if I have a hybrid? I don't like killing.
    Community Answer
    You can keep it, but the other fish might pick on it, or it might not be strong enough to survive and might die. A good option would be to buy a small tank (but big enough for the fish's comfort) and keep it in there. Keep an eye on it, though.
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  • Question
    Can I keep livebearers outdoors when the temperature is 5-10 C without a heater?
    Community Answer
    No, they will die. The temperature range for livebearers is 18–29 C.
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  • Question
    Do I need to cull fish? It sounds cruel.
    Community Answer
    You don't need to, but if you breed for profit, you wouldn't make any money if you can't sell fish or if your reputation is damaged. With ugly fish, you can't breed them and make more ugly fish, so you could give them away or cull them. There are ways to cull them without being too cruel.
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      Tips

      • Tank dividers can come in handy if you don’t have the option of setting up a separate spawning or nursery tank.
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      • Cull weak and diseased fry from each crop of offspring so the healthy young aren’t forced to compete for resources.
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      • Cover the bottom of the tank with a heavy substrate material like loose stones or marbles. Eggs deposited by scattering fish species will nestle into the space between the substrate, keeping them off-limits to scavenging adults.
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      Warnings

      • Keep in mind that as the number of fish goes up, the amount of available tank space goes down. Think carefully about whether you have the means to support an extensive colony before you make the decision to begin breeding.
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      References

      1. ↑ https://fish.mongabay.com/breeding.htm
      2. ↑ https://fish.mongabay.com/breeding.htm
      3. ↑ http://www.aquaticcommunity.com/breeding/condition.php
      4. ↑ https://nippyfish.net/2011/03/09/conditioning-bettas-for-breeding/
      5. ↑ https://www.ratemyfishtank.com/blog/breeding-freshwater-fish
      6. ↑ http://aquariuminfo.org/discus.html
      7. ↑ http://fins.actwin.com/fish/mirror/breeding.html
      8. ↑ http://fins.actwin.com/fish/mirror/breeding.html
      9. ↑ https://www.ratemyfishtank.com/blog/breeding-freshwater-fish
      1. ↑ https://www.ratemyfishtank.com/blog/breeding-freshwater-fish
      2. ↑ https://www.petful.com/misc/how-do-fish-mate/
      3. ↑ https://fish.mongabay.com/breeding.htm
      4. ↑ https://fish.mongabay.com/breeding.htm
      5. ↑ https://www.ratemyfishtank.com/blog/breeding-freshwater-fish
      6. ↑ http://fins.actwin.com/fish/mirror/breeding.html

      About This Article

      Article Summary X

      To breed fish, start by transferring a healthy male and female fish to a separate tank that's at least 5-10 gallons. Then, feed the fish a high-protein diet to help encouraging breeding, and replicate any conditions the fish would experience during their mating season in nature, like an increase in water temperature or a change in lighting. Once the fish mate and the female has laid eggs or given birth, transfer the parents back to their original tank so they don't hurt the fry. To learn how to take care of young fish fry after they hatch, scroll down!

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