How to Breed Glofish?

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Glofish are the ultimate cool addition to any aquarium. There are multiple species and many beautiful colors to choose from. Whether you like cosmic blue, electric green, galactic purple, moonrise pink, starfire red, or sunburst orange, there’s something for everyone. However, glofish are pretty expensive.

They usually cost 4-5 times more than their non-glowing counterparts. It would be costly to buy multiple groups of glofish for multiple aquariums. So, what if you bred your own glofish from just a few pairs? Is this doable? If so, how? That’s exactly what we’re going to cover in today’s article! But first, you might be wondering—

Is it Illegal to Breed Glofish?

Breeding glofish per se isn’t illegal. But this strain of fish is patented and trademarked by Yorktown Technologies, L.P. Since it’s a patented and trademarked “product”, you can’t legally breed the fish for profit. Selling or trading any glofish you breed is prohibited.

There’s no problem with breeding them just for personal use. If you want to breed more glofish to add to another aquarium, rest assured that the police won’t bust down your door. But keep in mind that breeding your glofish over multiple generations can result in duller-looking fish.

For the best results, you should breed glofish only with themselves. Breeding a glofish danio with a regular danio for example might lead to a weaker glow. But this can happen nevertheless, even if choosing the perfect parents. That’s because of how the fluorescent genes are expressed.

When a fish egg is fertilized, it receives an injection of fluorescent protein genes. That’s how this strain is genetically modified. It starts with a full set of activated fluorescent genes. When breeding the fish yourself, you won’t know how many of the genes will be active or silenced. It’s harder to control the process just via artificial selection.

Breeding Glofish at Home

Breeding glofish goes just as you’d imagine. If you’ve already bred other fish species, nothing should come as a surprise. All you need is a breeding pair, the right setup, and some maintenance work. But let’s cover the steps one by one:

– Select a Breeding Pair

The most important thing you need to breed fish is a breeding pair. But it’s not as simple as picking one male and female fish and waiting for the magic to happen. For the best results, you have to make your choice carefully.

Look for male and female fish that exhibit more extreme traits. Choose the brightest, largest, most healthy-looking fish for the pair. And since we’re talking about traits, I’d recommend you choose fish of the same color. This will help you maintain the same brightness and glow in the offspring. So, if you have green male fish, breed them with green female fish, for example.

If you don’t yet have any glofish to breed, you might also want to consider what species to buy. There are five species you can choose from. You can pick between glofish bettas, danios, barbs, tetras, and sharks. They’re all egg-scatterers. But their desired water parameters for breeding might vary. We’ll talk more about this in the following points.

– Setup a Breeding Tank

To set up a breeding tank, you’ll first have to choose the right size aquarium. This will depend on the species you want to breed. But most glofish have similar requirements. For example, a breeding tank for barbs, bettas, and danios should be between 5-10 gallons. Tetras need a little less room so a 3–5-gallon tank should suffice. Sharks, on the other hand, require a large tank. You’ll need at least 75 gallons or more for breeding glofish sharks.

Next, you’ll need to think about the substrate. Most glofish species don’t require any. Keeping them in a clean-bottom tank makes cleaning a lot easier. However, adding a substrate doesn’t negatively affect the breeding in any way. You might want to consider using a substrate if you want to add some plants to the aquarium.

Sharks are an exception, again. They’re bottom-dwellers. Since they spend most of their time at the bottom of the aquarium, adding some substrate becomes non-negotiable. A 2-inch-high layer of gravel should suffice though.

Next, add some hiding spots. These can be natural, like plants, driftwood, or rocks, but also artificial ornaments. Whatever works. Some fish species like bettas and tetras prefer breeding and laying eggs in hidden places, so providing that will encourage them to breed faster.

You’ll also have to install some aquarium lights. Good lighting promotes faster hatching and growth. If you want to breed large, healthy fish, light exposure is the way to go. Lighting will also maintain the growth of plants in the aquarium. Just remember not to leave the lights on 24/7. Fish also need to get some rest, and non-stop light exposure prevents that. Around 12-16 hours of light per day is enough for the best results.

Finally, don’t forget to add a filter! Clean water is crucial for the growth and development of healthy fish. The filter you choose doesn’t matter as much, as long as it isn’t too powerful for the tank you’re working with. I often use a regular sponge filter in my breeding tanks. It’s gentle and efficient for tanks up to 75 gallons, depending on the brand and size.

– Set the Right Water Parameters

The ideal water parameters are slightly different between glofish species. You’ll have to adapt the tank conditions accordingly. Here’s a quick rundown of the ideal ranges for each fish:

  • Bettas: The ideal temperature goes between 75-81°F. The pH should be slightly acidic to slightly alkaline (6.5-7.5). Bettas also prefer very soft water (3-4 dGH or 50-66 ppm).
  • Danios: This species prefers temperatures between 70-78°F and slightly alkaline water with a pH between 7.0-7.8. Danios thrive in soft to very soft water (3-8 dGH or 50-140 ppm).
  • Tetras: The ideal temperature for this species is 70-85°F. The water should be slightly acidic to slightly alkaline with a pH between 6.5-7.5. Tetras prefer soft water (4.0-8.0 dGH or 80-140 ppm).
  • Barbs: They prefer temperatures between 77-82°F and slightly acidic to slightly alkaline water (pH 6.0-8.0). Unlike other glofish species, barbs are very adaptable to different degrees of water hardness. They can live just fine in soft to hard water (5-18 dGH).
  • Sharks: The ideal water temperature for glofish sharks is 75-81°F. The water pH should fall between 6.0-8.0. Sharks thrive in soft to moderately hard water (5-11 dGH).

Depending on the water quality in your area, you might have to use a water softener or water hardener to reach the desired dGH value. Most glofish species prefer warm water, so you might also have to add a heater to the breeding tank.

This will keep the water temperature stable if the room temperature is too low or fluctuates a lot throughout the day. Water pH shouldn’t be a problem. Most fish do well in 7.0 pH water, which is the average value for most water sources. If you’re unsure, you can also test the water with a pH strip.

– Feed High-Quality Food

This goes for both the breeding pair and the fry. Good nutrition is just as important as setting up the right water parameters. Your fish need nutrients to create healthy fry. Young fish also require a nutritious and balanced diet to grow and develop.

You should feed the adults once to twice a day at most. The fry need more frequent feedings, between 4-6 times a day. And the food you offer them is just as important. While all the fish can survive on just fish flakes, you should do your best to include a variety of fresh and high-quality foods in the diet. Live food is especially important for nutrition in growing fish.

In the wild, the five species of glofish prefer slightly different diets. But in captivity, you can feed them the same things. Bettas and danios need higher protein meals. Tetras, barbs, and sharks require a more balanced diet, including more plants. All fish should get a combination of live, frozen, and dried foods.

For protein, you can include brine shrimp and other small crustaceans, bloodworms, daphnia, and insect larvae. Algae wafers or pellets, and green vegetables like peas and spinach make great sources of vitamins, fiber, and plant pigments.

– Remove Adults After Breeding

All glofish species, like any other fish, lack caring instincts for their young. Once hatched, the fish can manage just fine on their own. Actually, the adults represent a danger for the eggs and newborn fish.

Danios, tetras, barbs, and sharks are known to eat the fertilized eggs and the newly hatched fry. They’re all opportunistic feeders, so they’ll gobble down anything small enough to fit into their mouths. That’s why I always recommend separating the adults from the tank as soon as breeding is over.

Compared to its counterparts, the betta fish doesn’t usually eat its eggs or fry. But it’s not unheard of either. In any case, even if the glofish adults wouldn’t pose a direct threat, it’s still a good idea to keep them separate. I suggest keeping the new fish in the breeding tank until they reach their full adult size.

Introducing them into the main tank too early might stunt their growth. The fish are still too small to keep up with the competition. Since they’re at a physical disadvantage, the adults can outswim them and eat all the food before the young have any chance to feed.

– Monitor the Eggs

Once the eggs have been fertilized, you can move the adults back into the main tank. Now comes the easy part. All you have to do is keep an eye on the eggs and wait. Provided that the water parameters and lighting are good, the eggs should hatch in a few days. The fish eggs are very small and light-colored or nearly transparent.

You can tell when an egg has been fertilized.  There should be a small grey or black dot in the middle. From the moment of fertilization, each species takes a different amount of time to hatch. During this time, you should monitor the water parameters daily.

If you can see the eggs changing color and getting larger, you know for sure that you’ve got some little fry on the way. Betta fish hatch in about three days and take another two days to start swimming and feeding. Danios eggs hatch in one and a half to two days and take another two days to start swimming. Tetras hatch in a record time of just 24 hours but take three days to become free-swimming.

Barbs will hatch in 1 and a half days, but take five days to swim. Shark eggs take around 5-7 days to hatch, plus a couple more days for the fry to become free-swimming. Don’t remove the yolk-sacs after the fish finish hatching. They will spend the first few days feeding off the sacs until they develop enough strength to swim.

– Start Feeding the Fry

Look for free-swimming fry. Once the young fish have finished feeding on the yolk-sacs, they will roam around looking for more food. This means they’re now ready to start eating something more substantial. When newly hatched, all fish fry require a carnivorous diet.

They’ll also need a higher feeding frequency than the adults. So, you should feed the fry a variety of meat sources around 4-6 times a day. You should only feed them very little every time. The food should also be small enough for them to eat comfortably.

Feed them freshly hatched brine shrimp, micro worms, and high-quality micro pellets until they grow large enough. As the fry grow and develop, you can slowly decrease the feeding frequency and introduce new foods. Crushed fish flakes would make a good addition later on.

– Maintain Fry Tank

The fry won’t spend a lot of time in the breeding tank. They usually take just a few weeks to reach maturity. However, maintaining the fry tank is still important. You don’t have to do anything different than you would normally.

Just check the water temperature, filter power, and lights daily. Perform a partial water change (around 30%) once a week. Also, remember to do some more in-depth cleaning every two to three weeks. Wipe down the aquarium walls, clean the substrate, and clean and trim the aquarium plants.

I don’t recommend replacing filter media very often. This can impact the beneficial bacteria colonies in the tank. However, filters can sometimes become clogged. In that case, they won’t work at full power. You might want to check the filter when you perform a thorough tank cleaning. Clean any dirt or algae buildup that might get in the way.

How Often do Glofish Breed?

There’s some variation depending on the species. But on average, egg-laying fish can breed every 12 to 14 days. This is true for bettas, tetras, and barbs. Danios can breed more often, about every 10 days. I can’t say much about sharks, because these are notoriously difficult to breed in captivity. This species is too territorial and aggressive.

I should also mention that not all glofish carry their eggs for the same amount of time. Barbs and danios carry eggs for 3-4 days. Bettas and tetras, on the other hand, might take up to 14 days. But overall, all glofish species are quite prolific, laying between 100-400 eggs during each breeding period.

Most glofish species reach sexual maturity at around 12 weeks. But some species take longer to be able to reproduce. Betta fish become adults after 12 weeks, but don’t stop growing until around 12 months. They should be 4-12 months old before they start breeding. Similarly, danios should be 7-18 months old to start breeding.

Will Glofish Breed in a Community Tank?

It can happen. Female glofish will release eggs as long as there are male fish around to fertilize them. So, if you have enough male glofish in a community tank, they can breed without issue. However, you’ll have to provide hiding places for the glofish. Egg-laying fish prefer to breed and keep their eggs hidden somewhere safe.

Of all the glofish species we’ve covered, only sharks won’t be able to breed in a community tank. But they don’t breed in separate tanks either. It’s recommended that you only keep one shark in a 75-gallon aquarium. So, they really don’t get along well enough to reproduce.

Sharks excluded, breeding glofish in a community tank isn’t difficult. However, I still suggest you use a separate breeding tank. The fish in the community tank might eat most of the eggs and even the young fry. If you want to breed as many glofish as possible, the community tank isn’t the best choice.

Conclusion

As you can see, glofish aren’t that difficult to breed. These strains aren’t any different than their original species. It should be easy if you already know some things about egg-laying fish like bettas, danios, or barbs. All you have to do is set the suitable water parameters and provide a spacious and well-decorated tank. Pretty soon, you’ll notice small, glowing fry swimming around.

Sharks make an exception, as they’re more challenging to breed. That’s because of their temperament and general dislike for other fish. You can still try setting up a breeding tank to see how things go. If you provide enough space, food, and the optimal water parameters, maybe you’ll be one of the lucky people who manage to breed rainbow sharks!

avatar I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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