Can Glofish and Goldfish Live Together?

Goldfish are among the most notorious tank fish species in the world, and it’s no surprise. After all, they can live for decades, when properly cared for, and can grow to impressive sizes under the right circumstances. Goldfish are also highly intelligent and can learn to distinguish between their owners and strangers.

Goldfish can also adapt to living in a community tank, so long as they are calm and friendly fish.

Glofish, on the other hand, encompasses several fish species. These include tetras, rainbow sharks, zebra danios, tiger barbs, and betta fish. As their name suggests, Glofish glow thanks to a genetic modification inflicted by humans. The goal was to obtain a fish species capable of detecting harmful environmental chemicals.

Okay, the name doesn’t suggest all that, but at least it gets the ‘glowing’ part right.

So, when it comes to pairing Glofish with goldfish, you’re actually talking about assessing each species’ compatibility with goldfish. This is exactly what we’re going to assess here today.

Do Glofish Get Along with Goldfish?

To clarify one important aspect, Glofish species aren’t any different from their regular counterparts. In other words, a Glofish rainbow shark isn’t that much different than a regular rainbow shark, other than its appearance. Whatever applies to one necessarily applies to the other.

Knowing this, how do these fish fare when paired with goldfish? The answer is – mostly poorly. That’s generally due to 2 primary factors:

1. Incompatible behavior

This point already eliminates bettas, rainbow sharks, and tiger barbs. The last 2, at least, are pretty much incompatible with any other community fish species. They are extremely territorial, males especially, and will display aggression towards anything entering their environment. Including a peaceful species like the goldfish.

Tiger barbs, for instance, take great pleasure in nipping at long-finned fish and the goldfish is the ideal candidate for that. Fin nipping is a serious issue, albeit harmless in appearance, since it can cause injuries and stress out the victim. Goldfish can experience a lower immune system due to stress and experience infections, parasites, and various diseases as a result.

Rainbow sharks will take those problems to a whole new level. As gorgeous and intriguing as they are, as vicious they can become. They won’t just jokingly nip at their tank mate’s fins. This fish will often display malicious intent due to its highly evolved territorial instincts, which is rather peculiar since rainbow sharks only behave like this in captivity. It appears that they are quite accepting of other fish species around them in the wild.

Bettas aren’t better either at this chapter. Betta males, in particular, are probably some of the most aggressive fish on this list. They often display exaggerated territorial behavior and will poke at any fish competing over the same space. Their volatile behavior will take off even more during the mating phase when the excess of testosterone blows things out of proportion. Keeping them with goldfish is clearly a bad idea since they can’t even live with each other. male-on-male violence among bettas is not only common but the norm.

2. Incompatible water parameters

To get to the meat of the problem, goldfish are cold-water fish. They prefer temperatures between 67 to 74 max, which already disqualifies most species on the list. All other species prefer warmer waters, which means it would be impossible to accommodate both the goldfish and any of the other species in the same environment.

Attempting that will lead to 1 of 2 potential outcomes:

• The goldfish will experience warmer waters than they’re used to – The repercussions of keeping your goldfish in warm waters may not become visible immediately. But, long term, the effects will pop out clearly. Warm water goldfish don’t die, but they show shorter lifespans overall. They will also become more stressed along the way, making them prone to disorders and premature death.
• The other species will experience colder waters than they’re used to – The reverse is also unacceptable. Warmwater fish forced to live in cold water will display high levels of stress and low levels of energy. They will also have difficulties reproducing or living their lives within normal parameters.

The only species that can match the goldfish’s environmental requirements are the zebra danios. These are also cold-water fish that do well in community tanks and will keep to themselves most of the time. I mentioned most of the time because zebra danios like nipping at some fish’s fins.

The good part is that you can mitigate this behavior by keeping the fish into larger schools of 10 individuals or more. This will keep them occupied enough to prevent fin-nipping behavior in the long run.

Other than that, zebra danios should be able to coexist in peace with goldfish, given several tweaks that we will discuss shortly.

Keeping Glofish with Goldfish

When pairing the 2, several aspects are worth considering:

– Tank Size

How large the tank should depends on the number and the type of fish. But there’s another aspect worth considering here since we’re talking about goldfish. Goldfish are known to grow up to 12-14 inches in the wild, sometimes even larger. In captivity, however, they almost never approach those sizes. Interestingly enough, though, goldfish are among the few tank fish species that display an astounding variety in terms of size.

Some goldfish will only grow up to 1-2 inches, while others can reach 6 inches in size. Also, goldfish raised in outdoor ponds tend to be the largest. This supports, at least apparently, the idea that this species’ enclosure size determines its growth rate and size.

So, if you want your goldfish to grow larger, provide it with more space. This is that much more important knowing that you will also have a school of several zebra danios around.

As a general idea, 1 goldfish needs at least 10 gallons of water, preferably 15, to ensure its comfort long-term. Adding more fish to the equation will complicate the problem a bit. A zebra danio will only measure around 2 to 2.5 inches, similar to a normal guppy, which means 2 gallons of water per fish should suffice. The problem is that zebra danios are schooling fish and do best in groups of 6 individuals minimum.

Some quick math will inform you on the ideal tank size to accommodate both species. I would suggest around 35-40 gallons, enough to provide enough space for plants and other tank decorations as well.

– Water Temperature

Fortunately, both these species are cold-water fish and fare their best in temperatures around 64 to 74 °F. This range is enough to accommodate both fish in the long run, so long as you prevent temperature fluctuations. The zebra danios is the more adaptable out of the 2 since they can withstand temperatures as low as 60 in case of need.

The problem is that they don’t appreciate sudden temperature variations, and the same stays true for goldfish. If you can’t ensure stable temperatures, get a reliable heating system to keep the environment stable and within acceptable parameters.

– Diet and Feeding

Both species have similar food preferences since they are both omnivorous. However, this topic is slightly more complex than most people give it credit for. It’s not enough to throw some fish food in the tank and call it a day. Here are some noteworthy facts about feeding goldfish that you might want to remember:

• Flakes and pellets are tricky – It’s not that they’re not nutritious, but that they disintegrate fast in the water, making it difficult to remove them before they begin to decay. Your goldfish will also swallow air when attempting to get them at the water’s surface. With time, this feeding behavior may cause digestive issues. The latter problem also occurs in pellets, although, at least, these don’t sink, making it easier to remove the leftovers.
• Store-bought live food – I don’t recommend it. You have no idea the conditions that the live food has endured, and you can’t verify the quality. Getting live food like brine shrimp or tubifex worms from fish shops is a surefire way of carrying various diseases into your goldfish tank.
• Store-bought freeze-dried food – This is the safest option since freeze-dried food minimizes the risk of illness.
• Home-grown live food – Homemade live food cultures are highly popular among passionate aquarists invested in their goldfish’s wellbeing. Just set up a live culture system, and you will have a never-ending supply of fresh and nutritious food for your fish.

All these points also apply to zebra danios, which will eat whatever they can get their mouths on.

As an extra piece of advice, never feed your fish more than what they can eat within 2 minutes. This goes for both goldfish and zebra danios. Constipation is a serious issue among overfed fish, along with a boost in food leftovers that will decay on the tank’s substrate.

Controlled feeding will protect the fish and keep their environment cleaner for longer.

– Water Changes

The frequency and amount of water changes vary depending on how many fish you have and the tank’s size and type. If your tank is rich in plants, low on algae, and generally clean and well-maintained, you may not need frequent water changes with a proper filtering system in place.

As a general rule, try to change your fish’s water at least once per week. This is important, especially for a community tank housing a lot of fish species with different needs. Whatever you do, don’t change too much water at one time. Only change around 15% of the water to prevent disrupting the cultures of beneficial bacteria and diluting the essential minerals in the water.

– Number of Fish

I can’t really recommend anything carved in stone in this sense since it all comes down to what you’re most comfortable with. If you’re rather inexperienced in the aquarium business, stick to the minimum. That would be 1 or 2 goldfish and a group of 6 zebra danios. Decorate the tank with plants, rocks, wood, and other elements, learn about each species’ needs, and stay low until you get some experience.

If you’re already experienced, the sky is the limit, really. Just make sure you don’t keep more than 2 goldfish per tank since that would require a major investment in additional space.

Conclusion

Zebra danios and goldfish are both relatively easy to keep, provided you personalize their living space to accommodate both species. As for the other species of Glofish, forget about them, as they’re not compatible with the goldfish.

If you do want a rainbow shark or a tiger barb, I suggest setting up a different environment for them.