How to Tell if Your Fish Is Having Babies
Use this method for live-bearing species., Identify the males and females., Look for mating rituals., Check for a pregnancy bulge., Look for a red or black spot., Decide how to prepare for the young fish.
Step-by-Step Guide
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Step 1: Use this method for live-bearing species.
Guppies, mollies, swordtails, and platies are probably the most common live-bearing aquarium species.
The males and females of these species mate, after which the females form eggs within their bodies.
Over the course of a month or two (for most aquarium species), the eggs hatch into fish, and the mother gives birth.
Search for the name of your species online to discover whether it is egg-bearing (oviparous) or live-bearing (viviparous). -
Step 2: Identify the males and females.
As a general rule, male fish of live-bearing species are brighter or more elaborately colored, and have a narrow, long anal fin on their lower side next to the tail.
Females tend to be more drab, with a triangular or fan-shaped anal fin.
If you can identify their sex, you'll have an easier time telling whether two fish are fighting (typically two males or two females), or whether they are mating or preparing to mate (one male and one female).
Some species are more difficult to tell apart, and may require an expert from an aquarium store. , Different fish species can behave very differently during pair-bonding, amplexus, and other mating-related behaviors.
In many species, including most gouramis, the male chases the females around energetically, sometimes even causing scrapes, bites, or other damage.
In others, such as discus, a male and a female will work together to defend one area of the tank from other fish.
In either case, when actual mating occurs, this may involve the male and female gripping each other, turning upside down, wriggling around each other, or more subtle activities that are difficult to see. , The female fish will grow a bulge at the back of the abdomen.
The abdomen typically grows over the course of 20–40 days, either into a large, rounded shape or a "boxy" shape.
Some species such as balloon mollies have a natural bulge further forward, just below the gills.
Overweight males may develop a bulge in the front chest.
If you skip feedings for two or three days, an overweight bulge may shrink, while a female's pregnancy bulge will note. , Pregnant female fish often develop a "gravid spot" on the abdomen near the rear vent.
This is typically black or bright red, and grows more pronounced over the course of the pregnancy.
Some fish always have this spot, but it will typically grow brighter or darker during once the fish is pregnant. , Raising young fish, or fry, can be extremely challenging, and usually requires an entire separate tank so the adults or water filter does not harm them.
If you are not ready for the task, try contacting an aquarium store or an experienced aquarium hobbyist who might be willing to help you or take the fish from you.
If you do decide to take care of the young, you can start with the section below on raising young, but researching your specific fish species as well is recommended. -
Step 3: Look for mating rituals.
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Step 4: Check for a pregnancy bulge.
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Step 5: Look for a red or black spot.
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Step 6: Decide how to prepare for the young fish.
Detailed Guide
Guppies, mollies, swordtails, and platies are probably the most common live-bearing aquarium species.
The males and females of these species mate, after which the females form eggs within their bodies.
Over the course of a month or two (for most aquarium species), the eggs hatch into fish, and the mother gives birth.
Search for the name of your species online to discover whether it is egg-bearing (oviparous) or live-bearing (viviparous).
As a general rule, male fish of live-bearing species are brighter or more elaborately colored, and have a narrow, long anal fin on their lower side next to the tail.
Females tend to be more drab, with a triangular or fan-shaped anal fin.
If you can identify their sex, you'll have an easier time telling whether two fish are fighting (typically two males or two females), or whether they are mating or preparing to mate (one male and one female).
Some species are more difficult to tell apart, and may require an expert from an aquarium store. , Different fish species can behave very differently during pair-bonding, amplexus, and other mating-related behaviors.
In many species, including most gouramis, the male chases the females around energetically, sometimes even causing scrapes, bites, or other damage.
In others, such as discus, a male and a female will work together to defend one area of the tank from other fish.
In either case, when actual mating occurs, this may involve the male and female gripping each other, turning upside down, wriggling around each other, or more subtle activities that are difficult to see. , The female fish will grow a bulge at the back of the abdomen.
The abdomen typically grows over the course of 20–40 days, either into a large, rounded shape or a "boxy" shape.
Some species such as balloon mollies have a natural bulge further forward, just below the gills.
Overweight males may develop a bulge in the front chest.
If you skip feedings for two or three days, an overweight bulge may shrink, while a female's pregnancy bulge will note. , Pregnant female fish often develop a "gravid spot" on the abdomen near the rear vent.
This is typically black or bright red, and grows more pronounced over the course of the pregnancy.
Some fish always have this spot, but it will typically grow brighter or darker during once the fish is pregnant. , Raising young fish, or fry, can be extremely challenging, and usually requires an entire separate tank so the adults or water filter does not harm them.
If you are not ready for the task, try contacting an aquarium store or an experienced aquarium hobbyist who might be willing to help you or take the fish from you.
If you do decide to take care of the young, you can start with the section below on raising young, but researching your specific fish species as well is recommended.
About the Author
Joshua Harvey
Brings years of experience writing about creative arts and related subjects.
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