Livebearing fish are called so because they give birth to live young (called fry), unlike most fish, which lay eggs. Livebearers
include guppies, mollies, platies, swordtails and a number of other less well-known species.
Q: How do I tell the difference between male and female livebearers?
A: Adult male livebearers have a gonopodium (breeding tube) which is an adapted anal fin. This is the most reliable way
of telling the sex of a livebearer. Males also tend to be smaller, and slimmer.
Q: How many males/females should I have in my tank?
A: If you want to breed livbearers, the best ratio is either 2 or 3 females per male. Males tend to pester a single female,
and become aggressive. You can keep only males or only females in a tank. Females may come from the local fish store (LFS)
already pregnant. Males may bother other fish, occasionally if there are no females, but it is not generally violent.
Q: Is my female pregnant?
A: The usual answer to this is yes. Even at a young age, if a female has been in a tank with a male, she is likely pregnant.
Often they will come pregnant from the LFS. When pregnant, most livebearer females will have a gravid spot; a black patch
behind their stomach. On black or dark fish you won't be able to see this. A pregnant female will have a squarish look to
her stomach area. The squarer she looks, the sooner she will give birth. You should also feed the pregnant female with high-protein
live or frozen foods to have the best chances of healthy fry. Frozen or fresh bloodworms, brine shrimp, daphnia etc. are great
foods for the expectant mother.
Q: When will my female give birth?
A: Most livebearers will give birth every 30 to 45 days. Sometimes they will hold fry for a while. Be patient. With some
livebearers, water changes can help induce birth, so make sure to keep up with your weekly water changes. Mollies will often
give birth with the addition of a little salt to the tank. Livebearer females can hold sperm. So even if you have no males
around, she may have up to 4 batches of fry. Take this time to prepare for the fry by either getting a breeding trap or setting
up a fry tank.
Q: My female gave birth! What do I do now?
A: The first thing you need to do is separate the adult fish from the fry. The best thing is to have a fry tank set up.
A fry tank is usually a small, cycled tank with a sponge filter. Second best option is to catch the fry and put them in a
breeding trap (available at your LFS), which keeps the fry in a separate container inside the main tank. If you have your
livebearers in a community tank, and do not separate the fry, almost all adult fish will eat the fry. A heavily planted tank
may give enough hiding places for a few fry to reach adulthood. Fish with non-conventional mouths like otos or plecos don’t
usually eat fry. Healthy fry will not usually get sucked into the intake of your filter, but you can cover the intake tube
with either sponge or clean stockings if the filter is very strong.
Q: What do I feed the fry?
A: You will need to feed your fry up to 5 times a day when they are young. The best food for livebearer fry is live baby
brine shrimp. There are several DIY ways to do this, or you can buy a small hatchery from your LFS. You can also feed them
special fry foods like Hikari First Bites or Liquifry for livebearers. Another option is to feed hard-boiled egg yolks that
are crushed up, although this tends to foul the tank rather quickly. You can also feed the fry finely crushed flake, although
this is the least nutritious option. To make it, put some flake in a sandwich or ZipLock bag and crush it with a rolling pin,
the bottom of a jar or the back of a spoon. Fry have fast metabolisms, you will need to feed them often, and change water
more often. Two or three water changes a week will keep your fry healthy and growing well. The better the food you feed your
fry, and the better condition the water is, the healthier and faster your fry will grow.
A final note: Many livebearers are raised in intensive breeding conditions, leaving some livebearers unhealthy and generally
weak. A lot of interbreeding and lack of natural selection has not been good for livebears, and it is not uncommon for females
to die soon after giving birth or to have fry with genetic defects like bent spines.