How to tell if a Glofish is Pregnant
Glofish are some of my favorite tank occupants due to their bright colors and futuristic look. They are easy to care for but can be tricky to breed since the females look perpetually pregnant and the parents will often eat their eggs before you even know they’re there.
If you’re wondering how to tell if a Glofish is pregnant and what to do if they are, check out this guide I put together to help you navigate the mysteries of pregnant Glofish and ensure their babies have a safe, healthy start.
What Does a Pregnant Glofish look like?
You can tell male and female Glofish apart based on how they look: male Glofish are slimmer while female Glofish have a more rounded, pot-bellied look. This natural look can often make female Glofish appear pregnant when they’re really not.
To be entirely accurate, female Glofish are never pregnant. They’re not live-bearing fish; Instead, they carry and lay eggs. Technically, animals are only considered pregnant if they’re carrying live young. However, “pregnant” is often used casually to refer to a fish or animal who is carrying and ready to lay eggs, so I – along with most participants in the aquarium community – will still use the term “pregnant” when referring to Glofish.
A pregnant Glofish will look slightly more rounded than usual when she is ready to start laying eggs. It can be hard to tell if a Glofish is pregnant by looking at her, so you will want to rely on behavioral cues instead.
How Long do Glofish Carry Eggs?
Glofish develop eggs once they reach sexual maturity which is usually when they’re about 3/4th of an inch long. Once a female Glofish is pregnant, they wait to lay their eggs in the presence of male Glofish after engaging in mating rituals. These involve chasing each other around the tank and performing “spawning embraces” in which both fish press close to each other and seem to wiggle or vibrate together.
Once the eggs are laid, the female will develop more eggs and carry them till they are ready to lay again, so female Glofish are almost always carrying eggs.
What You Need to Know About Glofish Eggs and Fry
It’s quite likely that your female Glofish has already laid eggs if she’s young, healthy, and in the presence of a male. Since the eggs are incredibly small, though, and the adults like to eat them, you’ll need to take a few steps to ensure the eggs survive and the babies – called fry – get a healthy start.
First, keep an eye on the behaviors of your fish to see if they start exhibiting mating signs. If you have young, healthy Glofish who don’t seem interested in mating, try feeding them some high-quality food and, when the female Glofish is pregnant and looking rounder than usual, try a 50% water change or move them to a well-established mating tank that only has a few inches of water. This can often encourage spawning, which is when the female expels the eggs which will drift to the bottom of the tank where the male fertilizes them.
You’ll want to place marbles, gravel, or a thin grate-like sheet in the bottom of the tank which will provide a safe space for the eggs to drift down into where the adult fish can’t eat them. Once eggs are laid and fertilized, they usually hatch after about 24 hours. The fry will then take another 24 hours to begin emerging from the rocks or marbles. They will be so tiny at this stage that you might not be able to see them.
Once your fry is swimming freely in the tank – usually 2 or 3 days after they hatch – you can feed them with commercial fry food. This will be powdered food that is small enough for your fry to eat with enough nutrients to help them grow.
If you’re wondering how to tell if a Glofish is pregnant, the answer is quite simple: chances are, your female Glofish is pregnant already! Most Glofish spawn quite easily and frequently when they are being well-fed and kept in a clean tank. If you want the small fry to survive, place marbles or some kind of rough substrate in the bottom of the tank to hide the eggs from the adults, and you should have little baby Glofish swimming around your tank in no time at all!