Glofish danios are the OGs. First developed in Singaporean labs in 1999, today, they’ve lovingly made their way into the homes of millions of Americans.
Stunning appearance, coupled with the most friendly demeanor, they’re truly among the best gifts science has to offer to the fishkeeping hobby.
In this guide, I will tell you absolutely everything you need to know about these fish so you can treat them the way they deserve.
Glofish Danio Quick Introduction
|Original Species||Zebra Danio|
|Tank Size||20 gallons|
|Temperature||65-77 degrees F (18-25 degrees C)|
Glofish danios were first created by genetically modifying zebra danios indigenous to rivers in India and Bangladesh.
In 1999, Singaporean scientists extracted the green fluorescent protein from the jellyfish and inserted it into the zebrafish embryo.
The main motive behind this genetic modification was to detect environmental pollution that plagues our water bodies.
After the initial success, the team developed red fluorescent zebrafish by inserting the gene of a sea coral and an orange-yellow fluorescent zebrafish by adding a certain variant of the jellyfish gene.
In the early 2000s, Texas-based Yorktown Technology bought the patent to create these fascinating fish. And the rest is history…
Glofish today account for roughly 10% of all aquarium fish industry sales.
Glofish Danio Lifespan
Glofish danios enjoy a pretty long lifespan. With proper care, they can live for around 5 years. However, the average age would be 3-4 years.
The effort you put into raising them plays a determining role in ensuring their wellbeing and extending their lifespan.
Glofish Danio Appearance
Glofish danios look nothing short of stunning. They have slender condensed bodies and a distinct barbel at the end of each lip.
Even with genetic modification and color morphs, these fish have retained the iconic five steel-blue horizontal stripes that fade into the dins and extend onto the tail fin.
The fins have a translucent and luminous look to them.
Like the rest of the glofish species, these fish glow under blue or black LED light. But they don’t produce the glow from within. Instead, their bodies simply reflect the lights.
Nonetheless, they look absolutely magical.
Glofish Danio Colors
Glofish danios come in 5 stunning colors. And judging by the names, I think these colors are also patented.
The 5 shades of glofish danios are Cosmic Blue, Electric Green, Galactic Purple, Starfire Red, and Sunburst Orange.
These beautiful colors and luminous properties are inherited from their parents.
While the first generation of glofish danios were genetically modified, the ones that we find in pet stores and homes today were born that way.
Therefore, all the rumors about them being dyed, injected with colors, or painted are false.
Also, the colors don’t get duller or fade over time as they grow older like it does in some fish like painted glassfish and jellybean cichlids.
And if you’re curious what colors the offspring would look like when glofish danios of 2 different colors mate, they will come out looking like either one of the parents.
No brand new color morph is formed.
Glofish Danio Size
Glofish danios are small fish. They only grow around 2 inches (5 cm) long on average. However, some whiz kids are known to get about 3 inches (7.6 cm) long.
And it apparently takes them about 6 weeks to grow 1-inch long. And they will reach their full-size potential by the time they’re 3-4 months old.
Keep in mind that there’s no one rule etched in stone about how fast your glofish danios will grow and how long they will take.
That being said, there are certain things you can do to ensure they reach their full-size potential without any hiccups.
Providing a bigger tank, feeding a varied and nutritious diet, and maintaining the correct water parameters definitely play a pivotal role in ensuring your glofish danios grow at the best rate possible.
And do you know certain mistakes from your side can stunt their growth? If you’re interested to read up on that, you might want to check out this article!
Glofish Danio Male VS Female
Since both male and female glofish danios have colorful dispositions, untrained eyes can’t tell them apart.
However, there are other subtle cues present that will help you distinguish.
Females usually have rounder and deeper bodies, while males tend to be slender.
Females are also often larger than males.
And lastly, turn on the aquarium lights and cast an eye over the patterns on their body. Males often sport brighter, more luminous stripes than females.
Glofish Danio Temperament
Glofish danios, like their original counterparts, are well-mannered fish. They can be described as easy-going and playful.
They spend a reasonable amount of time darting around the tank. They are pretty athletic like that.
Since they’re shoaling fish, you can expect this behavior in the tank as well.
They have a unique hierarchy established through playful, harmless, and non-aggressive behavior.
Naturally, they also have an interesting pecking order.
Since glofish danios are community fish, they don’t do very well on their own. So you need to keep a good number of them together for them to feel safe and comfortable.
Otherwise, they will turn to aggression – chasing, pushing, and nipping fins.
That being said, keeping them in huge groups can also cause them to be hyperactive.
Unlike most species, these fish are not exclusive to just one corner of the tank. Although they prefer the top and middle of the water column, they’ll just about venture anywhere.
And that’s the reason they’re often used as dither fish by hobbyists to ease the tension in the tank.
The only concern you should have regarding glofish danios’ temperament is their knack to nip fins. When stressed or agitated, they resort to nipping their tankmates’ long, flowy fins.
Glofish Danio Tank Mates
Some suitable tankmates for glofish danios are:
- Indian flying barbs
- Honey gouramis
- Scarlet badis
- Emerald pufferfish
- Ember tetras
- Bengal turquoise danios
- Burma danios
- Celestial pearl danios
- Dojo loaches
- Bronze cories
- Kuhli loaches
- Rummy nose tetras
- Neon tetras
- Rosy barbs
- Nerite snails
- Zebra snails
- African dwarf frogs
- Freshwater shrimps
- Blue velvet shrimps
Because of glofish danios’ aptitude to nip fins, you should avoid pairing them with slow-moving,long-finned fish like bettas, angelfish, and goldfish.
And due to their small demeanor, you should avoid keeping them with fierce fish with a strong predatory instinct.
Some fish to avoid for your glofish danio tank are:
- Tiger barbs
- Red devil cichlids
- Green terror cichlids
- Red-tailed sharks
- Convict cichlids
- Jack Dempsey cichlids
Glofish Danio Group Size
Glofish danios, just like their original species, are shoaling fish. So in the tank, you should at least strive to keep 6 of them together.
In nature, their wild counterparts move in groups of thousands.
Glofish danios are friendly for the most part. However, if you only keep a few of them, let’s say 2 or 3, it will make them anxious and irritated.
Consequently, they will become aggressive and nip at the fins of other fish.
Shoaling is an innate behavior for glofish danios. They find safety and comfort in numbers. Therefore, it’d be kinda morally wrong to keep just a few of them for your own convenience!
Glofish Danio Diet
Zebra danios are omnivores. They primarily snack on small crustaceans, worms, algae, and mosquito larvae in the wild. These opportunistic feeders aren’t picky at all about what they put into their mouths.
And obviously, we can say the same about glofish danios.
For a staple diet, carefully curate and choose 2 to 3 kinds of quality flake food or pellets that don’t contain low-quality ingredients or fillers.
You can then fortify their diet with protein-rich options like brine shrimp, freeze-dried bloodworms, larvae, daphnia, and tubifex.
Occasionally giving blanched veggies like cucumber, zucchini, and romaine lettuce will also benefit their health.
I’ll jot it down in a list below for easy reading.
Foods You Can Give Your Glofish Danio
- Sinking pellets
- Flake food
- Frozen bloodworms
- Frozen blackworms
- Brine shrimp
- Blanched lettuce
- Blanched cucumber
- Blanched zucchini
If you’re interested, here’s a link to specialized glofish food from the same company behind glofish.
Apparently, this food is made with a proprietary blend that enhances the fish’s brightness. Hmm… Interesting!
Last but not least – here’s a link to Hikari Bio-Pure FD Blood Worms that I give my fish as treats. The worms are bio-encapsulated with multi-vitamins.
How Often And How Much To Feed Glofish Danios?
Glofish danios should ideally be fed 2-3 mid-sized meals a day. Give them an amount they can eat within 3 minutes.
And if you plan to give just 1 meal per day, offer food they can finish within 5-6 minutes.
Glofish Danio Water Parameters
Here’s what ideal water parameters for glofish danios look like:
- Temperature: 65-77 degrees F (18-25 degrees C)
- pH: 6.5-7.2
- Hardness: 5-12 dGH
- Ammonia: 0 PPM
- Nitrite: 0 PPM
- Nitrate: Below 20 ppm
- Water Movement: Weak
- Swimming Region: Top and middle
Glofish danios barely grow over two inches long. Therefore, they don’t really produce considerable bioload.
However, since they need to be kept in a big group, the waste they collectively produce can pose a problem.
Therefore, you need to ensure a sturdy filtration mechanism that can eliminate all the gunk they’ll produce throughout the day.
But no matter how reliable your filter is, it can only do so much.
Maintaining the tank’s health is an ongoing cycle that never ceases.
The rule of thumb is to carry out 20-25% water change every week, but this rule isn’t carved in stone. You can do more or less based on your stocking number and tank size.
But remember, the smaller the tank, the more frequent water changes it needs.
Their forebears, the zebra danios, inhabit slightly acidic ponds and rivers in the wild. So, your glofish danios would surely appreciate it if you could replicate that environment in their tank.
Glofish danios are super hardy fish. However, they’re still susceptible to spikes in ammonia and nitrite levels. Therefore, always aim to keep them at 0 PPM.
To assure the water quality hasn’t deteriorated, you need to test them at least once every week.
We swear by the API’s Freshwater Masterkit for that. Liquid-based kits are far more accurate than strip tests.
Here’s a link to API’s product if you are interested:
Glofish danios are often kept in small tanks. And as you already know, small enclosures are more prone to getting polluted quickly.
Toxic buildups happen way too fast in small tanks and spread even quicker. So, unfortunately, you always have to be on your toes to maintain a healthy tank environment.
Decomposing organic matter is also known to increase the water’s hardness. But as you read above, danios prefer acidic water. So, testing water parameters is all the more important.
The natural distribution of zebra danios is quite fast. Therefore, it’s believed that glofish danios have a wide tolerance range as far as water parameters are concerned.
Some blogs even claimed that they don’t need a heater at all. And I wholly disagree with that.
It’s true that glofish danios can thrive in a wide range of temperatures, but it’s still super important to invest in a reliable heater to maintain a stable environment.
Before we end this segment, here’s a quick checklist of tasks you should perform every day to maintain water quality to the T.
Things To Check Daily:
- Do a headcount and observe your danios’ behavior
- Check the status of equipment
- Check temperature
- Get rid of uneaten food
- Top off the water level
Things To Check Weekly:
- Wipe down the tank’s outer surface
- Scrape the insides of the tank
- Shake off debris from plants and decors
- Siphon the substrate
- Perform a partial water change
- Perform water tests
Things To Check Monthly:
- Trim live plants as needed
- Thoroughly clean rocks and decors
- Perform all tanks mentioned in the weekly checklist
- Change the filter media
Recommended Tank Size For Glofish Danio
10 gallons is the absolute minimum recommended tank size for glofish danios. That’s also the biggest tank capacity available on their glofish website. And they recommend adding 2 glofish danios per gallon of the tank space.
Guess what? All of the information dished out above is inaccurate and potentially fatal.
Although glofish are small fish, they are incredibly active and curious. Their favorite thing to do in the tank is dart around from one corner to another like a flash.
Therefore, I’d at least recommend getting a 20-gallon long tank as the bare minimum. Remember, I said a ‘long’ tank – they need more vertical space to cover swimming laps.
Now, let’s go back to the point that states ‘you can safely add 2 Danios per gallon of tank space.” It’s written on their official website.
By this logic, you can add 20 glofish in a 10-gallon tank. And my friend, that’s the most inaccurate thing I’ve heard in a while.
Even if you go by the ‘one inch per gallon’ rule, you can only add 5 glofish danios in a 10-gallon tank.
Before we end this segment, let me quickly go through a few reasons why small tanks will do more harm than good for your glofish danios.
Small tanks get polluted more quickly, which will stress your fish and expose it to numerous pathogens ubiquitous in the tank.
Water parameters change volatilely and suddenly in small tanks. A slight disturbance in one corner can be felt throughout the tank in a matter of a few seconds. And these abrupt changes will naturally shock and stress your fish.
Small tanks give rise to territorial disputes. Even peaceful fish like glofish danios will turn against each other. Now, this just won’t stress the fish but also lead to duels and injuries.
If there ever was a fish Olympics, glofish danios would surely take some medals home. These fish are highly athletic and energetic. And since small tanks don’t offer enough room for acrobatics, it can stunt their growth.
I listed just 4 reasons why small tanks are detrimental to your glofish danios’ wellbeing. But, frankly, I can go on and on about it.
But for now, let’s stop here.
And by the way, if you want to read some real comments left by hobbyists on keeping glofish danios in a 10-gallon tank, here’s a link to that:
Substrate And Decor For Glofish Danios
For substrate, you can choose between sand and gravel. The dark substrate will naturally bring out your fish’s colors the best.
Since glofish danios barely spend any time at the base, you don’t need to fuss around much about the substrate. They’re not exactly prone to substrate-related injuries.
While decorating your tank, you need to keep in mind that danios are prolific swimmers that require plenty of open spaces. Therefore, decorate the tank so that the middle portion is fairly open.
You don’t want to go overboard and add too many decors that will obstruct their swimming sessions.
At the same time, you need to ensure the tank isn’t too drab, as these fish are naturally curious.
You can also add rocks and caves – just make sure to place them strategically, so you don’t obstruct the swimming area.
My favorite decor that also serves as a hiding place is this Krusty Krab ornament from Penn-Plax.
If whimsical is your style too, I’m sure you will love it.
Lastly, add a slew of aquarium plants. They come with multiple benefits.
First, the water quality is going to improve. Live plants leach much-needed oxygen and nutrients into the water.
Second, plants will provide ample shelter and diffuse lights for the times your glofish feel stressed.
Like most cyprinid fish, glofish danios feel the most at home in well-planted aquariums. Some good plant choices would be java fern, amazon sword, water wisteria, hornwort, and java moss.
Don’t be afraid to mix and match different plant species to strike a nice balance between short, tall, and floating plants.
Recommended Equipment For Glofish Danio
There’s a reason the scientists behind these fluorescent fish first chose zebra danios to create glofish. These fish are astoundingly hardy.
Therefore, your glofish danios will spare you several beginner’s mistakes. They’re built solid.
However, let’s not make their resilience an excuse for keeping them in substandard environments.
For the sake of this article, we researched and reviewed dozens of equipment and came up with our top picks that are well-built, affordable, and have plenty of positive reviews.
Let’s check them out!
AquaClear 30 Power Fish Tank Filter
What We Love About It:
- Energy-efficient pump reduces operating costs
- 3-stage filtration: mechanical, chemical, and biological
- Lifetime warranty
- Comes with everything it needs to set up and run
- Some complaints about it being nosy
Fluval M50 Submersible Heater
What We Love About It:
- Built-in reflective technology mirrors surrounding colors
- 3-year warranty
- Slim profile
- Made with shock-resistant glass
- Operating thermostat can be tricky
Tetra Whisper Easy-To-Use Air Pump
What We Love About It:
- Super quiet operation
- Features sound-dampening chambers
- A few complaints about the pump being noisy
Breeding Glofish Danios
Breeding glofish danios is relatively easy compared to other fish from the glofish family.
But before getting to the crux of the matter, let’s see if breeding glofish danios is actually permitted by the law.
So, Is It Legal To Breed Glofish?
The official site for glofish reports that it is illegal to breed these fish.
However, if your glofish ever yield a few offspring, I doubt there will be two policemen knocking on your front door with handcuffs ready.
If you have glofish danios of both sexes present in the tank, they will produce a batch of fry at some point down the lane.
Just make sure that you don’t sell or barter them. I’m so paranoid that I wouldn’t even gift them to anyone!
Now, let’s go through the spawning process in detail.
Setting Up The Breeding Tank
Unfortunately, glofish danios don’t make the best parents. They will immediately turn to devour the eggs once they’re laid.
Therefore, if you want to improve the chances of the eggs turning into young fry, you better set up a separate breeding tank.
A 10-gallon tank would suffice. Anything bigger than that will only make it hard for your fry to find food later on.
The tank should be fully cycled, equipped with a reliable sponge filter, and covered with a bed of marbles.
Adding the marble layer isn’t for aesthetics. It will allow the eggs to fall between the cracks and save them from prying parents.
Encouraging To Spawn
Interestingly, glofish danios mate for life. They aren’t promiscuous. If they’re separated, or one of the partners dies, they will go their whole life without mating. Talk about true love!
So, the best way to breed glofish danios is to allow pairs to form naturally. For this, you will need to keep several young fish together in big groups. The pairs will form in the course of a few days or weeks.
Feed both parties a protein-rich diet like bloodworms, larvae, and small crustaceans. Once the spawning season arrives, you can notice the female’s body becomes slightly swollen and distended.
Now, transfer the bonded pair into the newly set breeding tank. Continue feeding protein-rich food and slightly elevate the temperature. Also, perform a big water change. These 3 things will encourage your glofish danios to spawn.
The Mating Process
The mating process in glofish danios isn’t super elaborate. At most, the male will chase the female, and both parties circle around each other.
Once the female is ready, she will lay up to 400 eggs – 2 to 3 at a time. And since danios are egg-scatterers, the adhesive eggs will be spread across the leaves, plants, and the substrate.
Once the male is done fertilizing, swiftly remove both parents from the tank as they won’t think twice before gobbling their own eggs.
The eggs will fall through the cracks of the marbles where they will reside and develop for the next 36-48 hours before ‘hatching.’
And remember, a glofish danio’s eggs don’t hatch in the same way as a crocodile, or a snake’s eggs would hatch. Instead, the eggs transform into different body parts.
If you’re interested to see what the glofish eggs look like, here’s a link to that.
Related: What Do Glofish Eggs Look Like?
Caring For The Fry
For the first few days after hatching, the young glofish danio fry will depend on the nutritious yolk sac attached to their bodies for much-needed nutrients.
The tiny wigglers will become free-swimming in the next 4-5 days.
At this point, you can feed them:
- Baby brine shrimp
- Egg yolk paste
- Pulverized flake food
And once the fry grow big enough to not fit into an adult fish’s mouth, you can safely transfer them back to the main tank!
Glofish Danio Diseases
Glofish danios are hale and hearty for the most part. However, they’re also prone to some diseases that plague freshwater fish like ich, parasitic infestation, and fungal and bacterial infection.
Ich is caused by a parasitic protozoan and is often the result of stress or an unmaintained tank. It manifests as tiny white specks throughout the fish’s body and is highly contagious.
At Urban Fishkeeping, we swear by this Ich-X Solution from Hikari to eradicate ich.
Nematode is another common infection that danios often contract. These parasites cause drastic physical changes in the fish, making it appear darker. But that’s not all. Your danio will also become increasingly weak and shed weight.
Most kinds of diseases and infections can be kept at bay as long as you monitor the tank’s living condition, perform regular water changes, and feed a nutritious diet.
Unfortunately, in addition to all those common ailments, glofish danios are particularly susceptible to a lesser-known health condition known as mycobacteriosis.
Mycobacteriosis is caused by several kinds of non-motile bacteria present in water. It spreads quickly and will infect the tank’s entire population in no time if you don’t take the right steps.
Your glofish danios will exhibit signs like skin inflammation, fin loss, ulcers, anorexia, and lethargy.
Sadly, mycobacteriosis isn’t easy to treat. The best course of action here would be to remove the infected fish immediately, perform big water changes, and pray that your other fish aren’t infected.
And also, note that mycobacteriosis is a zoonotic disease. It can transmit to humans as well. So don’t handle the fish or the tank if you have open wounds in your arms or hands.
Final Words: Glofish Danio Care Guide
The article got pretty long, didn’t it? Well, at least it covers every little detail you should know on caring for glofish danios!
Like the original species, glofish danios are hardy fish that thrive in a wide range of environments. They’re also a lot more forgiving of a beginner’s mistake than other fish.
These colorful fish can live in your home aquarium for over 5 years with the right care and diet!
Just make sure the habitat is clean at all times, the diet is nutritious, and the environment is stress-free.