How To Tell If A Tetra Fish Is Gravid

You've assembled your fish aquarium, stocked it with tetras, and filled it with plants. Now, as you observe your fish, you may notice some unusual behaviors or changes to your fish's body that makes you wonder if they're ready to breed. Once you've figured out if you have male or female tetras (or both) and spotted the signs that your fish may be mating, you'll be ready to determine if your tetra is gravid.

First, there's a terminology difference between gravid fish and pregnant ones. Typically, "pregnant" refers to fish that are live-bearing, while "gravid" refers to fish that are full of eggs ready to be laid. Tetras are egg-laying fish, which means they become gravid when they're ready to reproduce. Moreover, tetras can create dozens of eggs during a single spawning cycle.

But just how can you tell if your fish is gravid? Well, there are actually a few things to look for. For starters, it's best to look at your tetra from above to more easily see these changes. When looking, you'll notice a gravid fish becomes broader, with a rounded belly. This is, of course, because she's full of eggs. In addition, she may show some behavioral changes. These include an increase in appetite or seeking out hiding places to lay her eggs. If you have males in the tank, they may also become more interested in the females, as well as more brightly colored to try and attract the female for mating.

Sometimes, a fish may be mistaken for being gravid when they're actually ill, and vice versa. It's important to rule out any issues that could mimic a fish appearing gravid. Illnesses that can mimic this include dropsy (a fatal build-up in fluid in a fish), bloating, and digestive issues. The key difference is that a healthy, gravid fish will still be bright-eyed, alert, and interested in the environment around her, while an ill one will display additional symptoms. For example, the scales on a fish with dropsy will become more erect like a porcupine or pinecone. 

Once your tetra has laid her eggs, you may notice them in the environment. Tetra eggs are clear and small, and they easily stick to spawning mats, plants, and other materials in the tank. However, once fertilized, they'll become opaque-white. After a few days, the eggs will hatch, and the babies, or fry, will emerge. You'll want to feed them a special fry food, such as Ultra Fresh's Baby Fish Food, for optimal health. This food can also help support the energy needs of a gravid fish as she readies to lay her eggs. 

Overall, determining if a tetra is gravid can be tricky at first, but once you recognize the signs, you can enjoy the fun and joy of new life swimming around your tank in a few days.