Are Guppies Aggressive or Peaceful Fish?

Many fish enthusiasts are enamored with guppies. These colorful little fish are usually known as energetic, sociable, and peaceful, and they make great tank mates. However, under the wrong conditions, guppies can also become aggressive and territorial.

This type of behavior is hard to imagine in a guppy, but it’s very much possible.

Whether you’re already dealing with mischief-makers or you’re trying to be proactive, in this article I’m going to talk in detail about the how, the why, and the what when it comes to aggressive guppies. Keep reading to learn more about the causes and solutions for aggressive guppy behavior.

When Guppies Chase Each Other?

You may have already noticed this behavior in your guppies. It’s a common occurrence, and not something to worry about, for the most part. This chasing usually happens when male guppies are trying to mate, and they start pursuing female partners. So, if you see the smaller, more colorful fish chasing the bigger, duller fish, that just means your guppies are trying to breed.

However, this behavior isn’t completely harmless, especially in a tank where male guppies outnumber females. The constant chasing puts a big toll on your female guppies, leading to stress and atypical behavior. When this happens, female fish become sick and lethargic. They might start spending a lot of time hiding and they lose interest in feeding.

That’s obviously not something you want. Stress never helped anyone, and this behavior is damaging to your female guppies’ health. While less common, chasing can also happen between male guppies, especially in male-only aquariums. This type of chasing tends to be more aggressive, but not really threatening.

When male guppies are chasing each other, they’re competing for mating rights, or to establish dominance. In this case, guppies are trying to intimidate the competition, and the chasing is just for show. As long as things don’t escalate into fin nipping or fighting, you shouldn’t worry too much about it. But you’ll have to keep an eye on this behavior.

There are plenty of options to keep chasing to a minimum if you’re afraid about your guppies’ health. You could separate your male and female guppies in different tanks, and that’ll get rid of the mating males problem.

If you have a male-only guppy tank, make sure the space isn’t over-populated. Your guppies need plenty of personal space. If they’re all crammed together, they can get territorial. You can also add some plants and other hiding spots where your bullied guppies can seek refuge.

Why Male Guppies Fight?

Guppies are nicknamed the million fish for a good reason. These guys are prolific breeders, and male guppies are indiscriminatory mates. When there are no females around, or when there are too few females in the aquarium, male guppies can become aggressive towards one another.

Sometimes, male guppies can pick up fights with each other, whether when competing for breeding privileges or a given territory. Other times, they just do it to intimidate one another for no reason. This happens especially in crowded aquariums where fish feel threatened by the lack of space or by competition for food.

These fights are often just for show. Your male guppies might get rough with one other without causing actual injuries. However, if you notice that your bullied guppies are physically hurt in any way, that’s a sign that you should intervene. Check for signs of injury on their fins or tails. This shows that the infighting is getting out of control.

If this dangerous behavior persists, you should take serious measures to protect your fish. Upgrade to a larger tank, separate the aggressive fish, or add more females to the aquarium. You might also want to place the injured fish in a safe, low-population aquarium where you can monitor their healing.

Can Guppy Fights Result in Death?

This isn’t common, but it can still happen. Although it’s atypical behavior for guppies, fighting can result in fatal injuries, especially if the same bullied fish are attacked repeatedly. In extreme cases, bullied guppies can succumb to their physical injuries if these are serious enough.

But more often, injured guppies die of secondary causes, usually infections or parasites. That’s because when fins, tails, and skin are wounded, that leaves the fish vulnerable to harmful microbes. Even if the injuries aren’t deep or dangerous, your guppies can still contract a disease. To make matters worse, an infected fish can then be potentially harmful to other tankmates.

Still, these are very rare cases we’re talking about. Guppies rarely get aggressive with each other. For the most part, they just chase each other to scare off the competition. If you’re still worried about the worst-case scenario becoming reality, there are a few things you can do to maintain peace in your guppy tank.

Ensure there’s enough space in the aquarium. You wouldn’t like being crammed together with a bunch of people. Neither do your guppies like living in a crowded tank. This stresses them out and leads to territorial behavior. It’s best if each guppy has around 3 gallons of water. If you have a 20-gallon tank, that means you should keep around 7 guppies.

When there aren’t enough resources, guppies become competitive. To mitigate this problem, always remember to feed your fish enough. As nice as guppies are, everybody is a little harsh when they’re hangry.

Another way to diminish competition between male guppies is keeping a 1:3 male to female ratio. You definitely want to avoid keeping only males in an aquarium. If bullying still persists, you should separate the violent fish from the tank.

What to Do About Bully Guppy Fish?

If you took all the measures I’ve discussed above (providing space, feeding, adding more females) and some of your guppies are still acting aggressive, you should move them to a separate tank. Wait a couple of days before reintroducing them to the main tank. In the meantime, check to see if your other guppies have any injuries. If that’s the case, they’ll need treatment and close monitoring.

After some time has passed, try reintroducing the guppies into the main tank. Observe their behavior over the next few days. If they’re still hellbent on causing chaos, maybe they’re incompatible with their tank mates. Or maybe they’re just a-holes. Either way, you’ll have to keep them in a separate aquarium to prevent injuries.

You can try introducing new fish into the separate aquarium and see how things go. If your guppies get along well, then maybe the troublemaker fish just needed compatible tank mates. If you don’t have a well-equipped second aquarium, you can also gift these guppies to a friend, or try selling them.

Keeping the Right Male to Female Guppy Ratio

Guppies don’t like being alone. They need other tank mates to interact with. However, the sex of the fish also matters. We’ve already gone through what happens when males outnumber females in a guppy tank. It’s not fun, to say the least.

As a general rule of thumb, female guppies should always outnumber male guppies by at least 3 to 1. This way, there will be enough females for every male guppy fish, so there won’t be any competition for mates. However, there’s another important advantage. When females outnumber male guppies, this also leads to lower stress levels for the female fish.

With multiple females in the tank, male guppies won’t chase the same female all the time. The ladies get some well-deserved rest, and everybody’s happy. A higher female-to-male guppy ratio also leads to fewer pregnancies for the same female guppy, which leads to better health outcomes.

However, overpopulation could become a problem in a mixed-sex tank. If you want some population control, you can let the female guppies give birth to their fry in the main tank. The adults will eat many of the fry. If you want to keep the fry but don’t want to cram your aquarium, you need to move pregnant guppies to a different tank.

Can Guppies and Other Species Coexist?

Guppies are typically mellow, and they get along with just about anyone if the conditions are right. So, yes, they can live in harmony with other fish species, but there are some conditions. First and most obvious, the other fish you want to introduce into your guppy aquarium should also be peaceful.

For them to get along with your guppies, the new fish should have a similar personality. You can’t add aggressive species of fish that are much larger than your guppies unless you want your guppies to become live feed. The species should also be compatible when it comes to dietary requirements and water parameters.

The perfect tank mates for guppies will thrive on the same diet and in the same water parameters. These fish are also peaceful and energetic and have a size similar to guppies. Some beautiful species meet these requirements, including Mollies, Cory Catfish, Otocinclus Catfish, Swordtails, Platies, Harlequin Rasboras, Cardinal Tetras, Honey Gouramis, and Bristlenose Plecos.


While guppies are generally peaceful, they can become aggressive under the wrong conditions. Meeting their space, food, and social requirements is crucial if you want to keep your guppies stress-free and healthy. However, don’t let this discourage you from keeping guppies. Aggression isn’t common in guppies, and fatal injuries occur rarely.

If you encounter problems in your guppy aquarium, the solutions outlined in this article should reduce aggression. Also, keep in mind that guppies also have individual differences like any other animal. Sometimes, problems might arise due to incompatible tank mates.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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