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Are Angelfish aggressive to other fish? Angelfish are a popular freshwater fish kept by pet lovers the world over. Categorized in the genus pterophyllum, they come from the Amazon and Rio Negro rivers as well as the Orinico, all in South America, where they enjoy slightly soft water and leafy, verdant conditions.

They are a social species and it is always best to purchase them in groups but make no mistake, they are naturally hierarchical, and they can occasionally become aggressive. However, when you know what you are doing, this is easily preventable. Read on to find out all about Angelfish aggression both to tankmates and their own kind.

Are Angelfish Aggressive?

Once they hear that Angelfish are hierarchical fish, some fishkeepers may end up learning about their supposed aggression. This aggression happens as fish use territorialism and body language to maintain their place in the hierarchy or establish it after lower-ranking fish. These sorts of behaviors can include chasing other fish, swimming in front of them to get food, and small amounts of nipping.

Generally, these behaviors sort themselves out as your fish establish their place in the hierarchy – a crucial piece of social information that keeps them involved in the social dynamics of the tank. Isolation can also lead to other negative symptoms, so always give your Angelfish a group.

Are Freshwater Angelfish Aggressive?

Nevertheless, due to the groups they form in their natural riverine habitat, reshwater Angelfish are semi-aggressive and hierarchical. High amounts of organic matter such as logs and plants are found in their home in the wild. Thus, freshwater Angelfish are exposed to lots of different territories and may show hierarchical aggression in order to maintain their territory.

However, establishment and maintenance of the in-group hierarchy can paradoxically decrease aggression, as fish that understand their position will be less likely to challenge it.

Are Angelfish Aggressive To Their Own Species?

How To Prevent Angelfish Bullying Tankmates

If you want to prevent Angelfish from bullying same-species tankmates, it’s best to ensure they can coexist in different territories. This article has talked a bit about using driftwood and plants to separate up areas of the tank, but understanding fish’s territorial needs can go a lot further to preventing aggression.

Which Other Fish Can Trigger Angelfish Aggression?

Angelfish can be aggressive, but this isn’t necessarily with every type of tankmate. Aggression tends to be directed towards other Angelfish, and certain other species. Below are some common Angelfish tankmates that may become the objects of aggression occasionally.

1. Barbs

Of all potential Angelfish tank mates these are the fish that are most likely to become the objects of aggression. This is because Barbs can be semi-aggressive themselves depending on the species. It’s best not to keep large Barbs like the tinfoil Barb or Denison’s Barb with your Angelfish. But smaller, more peaceful Barbs like the Snakeskin Barb or Cherry Barb can work well as they can cope with similar water conditions.

However, Barbs can threaten your Angelfishes’ territory, as they are active fish and will certainly want to use the midwater section of your tank. Thus, like with most of the specific species mentioned in this article, it’s best to ensure you have a big enough tank of at least 65 gallons.

2. Discus

Angelfish and Discus fish can get on. However. fights may also break out. You just need to understand they are both schooling fish that prefer their own species and that they need a large enough tank so there are plenty of habitats. If you want to keep them together, it’s best to start with an aquarium of minimum 75 gallons to prevent any aggression.

Generally, Discus come from slightly slower moving water from Angelfish but both of them come from areas of high vegetation. You can separate the habitats by noting where in your aquarium the filter is and using a large piece of driftwood or series of rocks to section off a stiller section away from the filtration where your Discuss can hang out separately from your Angelfish if they would like.

Author’s Note: Generally, if aggression does occur, it will be the Discus fish who are on the receiving end, as they tend to be more peaceful than Angelfish.

3. Tetras

Tetras do hang out midwater, but as small schooling fish that aren’t necessarily huge swimmers, they won’t cross the paths of your Angelfish in the same way Barbs and Cichlids will.

Simply ensure you have a big enough tank of at least 50 gallons for both your Tetras and a group of 5 or 6 Angelfish and you should be fine. However, it can also help to feed your fish at different times as Tetras may go for the protein you feed your Angelfish, and your Angelfish may indeed retaliate.

4. Cichlids

Of all fish on this list, Cichlids are the most likely to have their territory overlap with your Angelfish. This is because they are small and fast-swimming fish that will often use the midwater column to swim around, and find food.

Luckily many Cichlids are hardy and won’t necessarily be intimidated by Angelfish aggression. However, if you want to ensure they don’t compete for the midwater section of the tank, it’s best that you buy a big enough aquarium. If you’re adding Cichlids on top of a group of 4 or 5 Angelfish, at least 60 gallons is needed.

What Can Cause An Angelfish To Become Aggressive?

Angelfish can become aggressive for a variety of reasons as outlined above, as well as due to competition for mates. However, some of the main ones include:

1. Poor Diet

Angelfish that are malnourished and eat a poor diet may become more aggressive as they compete over food. You may see tropical flakes marketed towards Angelfish and indeed you can use these as basic food, but instead, Angelfish do best with a protein-rich diet and may become aggressive in their search for other kinds of food if they do not get this.

For example, if you have small snail and shrimp tankmates and your Angelfish are lacking protein, they may turn predatory towards these small tankmates. Always ensure your Angelfish is getting enough protein!

2. Lack Of Territory

A tank that is too small, poorly laid out, or does not have enough different territories can trigger aggression as your Angelfish don’t have enough space to express their natural social behavior. However, this does not just apply within a group of Angelfish. It is one of the main causes of an Angelfish becoming aggressive to other tankmates.

Some fish such as Cichlids may occasionally have their territory cross over with Angelfish. Angelfish like to swim in a shoal midwater, so if there are tankmates that also inhabit this area such as Discus fish or even some small types of Tetras or Barbs, they may become the target of Angelfish aggression. Always use a big enough tank and use rocks and driftwood to separate areas so that fish species can keep apart if desired.

3. Stress From Water Quality

Poor water quality can alter your fish’s natural behavior and make them more predisposed to aggression. This is generally a good thing to catch early as it can also lead to other forms of illness. Aggressive fish can also become the victims of aggression and vice versa. If a fish is sick, it is more likely to be targeted by aggressive tankmates

What To Do About An Aggressive Angelfish

You may have done everything you can but found your Angelfish are still aggressive towards tankmates. Sometimes fish take a while to settle in, but it’s good to know how to deal with aggression when it does occur.

How To Break Up Fighting In Your Angelfish Tank

If it seems like fish are becoming unnaturally aggressive to each other, you may wish to separate them. To do this, you can isolate the most aggressive fish or the fish that is perpetrating the aggression with a net and keep it in a separate tank until you have sorted out the issue.

Author’s Note: Never try to break up fish aggression by introducing a distraction such as food. This is a bad idea as it becomes another thing that fish can fight over. Likewise, never introduce another tankmate, even though you may occasionally see this suggested online. You will just find that you have broken up the existing social dynamics and made things worse as opposed to better.

How To Tell When Your Angelfish Are Getting Too Aggressive

How will you know if Angelfish aggression is becoming out of hand? There’s no one hard or fast rule and sometimes, the less intervention the better as human intervention can upset the delicate tank dynamics. However, here are a few good benchmarks:

• Take into account the size of the tank mate that is being picked on. Small Tetras and shyer, small Barbs will suffer a lot more from Angelfish aggression than a larger Cichlid will.
• Does the aggression show signs of stopping? If it only happens over food or in a particular part of the tank, it may be that you can leave your fish until you can come up with a solution. However, if aggression happens all the time it can easily tire out the other fish and lower their immune system.
• Is the bullied fish starting to look sick? Fish won’t tell you with sounds that they are sick or stressed in the same way a dog will. However, it’s easy to see if a bullied fish is suffering too much if they start cowering in another part of the tank or showing signs of illness such as fin rot or lethargy.

Important Considerations In Understanding Angelfish Behavior

There are a few other things to consider when thinking about Angelfish behaviour and that is their natural habitat, and the dietary requirements. Any fish that does not have the correct conditions or is not eating the right food will inevitably show more aggressive behavior both within the same species and to other tankmates.

Angelfish need warm, soft water and if they don’t get this they can become stressed out, leading them to act aggressively.

However, one important consideration is to understand that there are many fish that come under the name of ‘Angelfish’. It’s best to understand that here we are talking about the freshwater Angelfish from South America, Pterophyllum.

Are Freshwater And Saltwater Angelfish The Same Species?

Freshwater and saltwater Angelfish are definitely not the same species! Therefore, if you accidentally purchase a freshwater Angelfish and keep it in saltwater conditions, not only will your fish show stressed and aggressive behaviours, they may actually die!

Saltwater Angelfish come from coral reef environments across the Pacific and Indian oceans and they generally feed on coral. Freshwater Angelfish have a very different diet in their natural habitat of South American waterways, feeding on insects and small crustaceans. They do not like salt in the water and prefer lots of driftwood and organic matter.

Bottom Line

Overall, Angelfish aggression needs to be understood from multiple angles and there are no hard or fast rules about whether Angelfish are or aren’t aggressive to other tank mates. It all depends on the size of the tank, how well you take care of your fish, and the tank mates in question. Fish aggression is never pleasant to watch, but hopefully, this guide will have shown you some of the things that affect it and what you can do to both prevent it and fix it when it happens.

Author’s Note: If you can’t tell the instigator, keep an eye on your fish. You may find that there is a more dominant fish that is bullying a subordinate fish. Sometimes, the more dominant fish tends to be bigger.

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