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Are Lemon Tetras Aggressive?

Lemon tetras are a species of tropical fish found in the Amazon River near Brazil in South America. Peaceful, hardy, and active, lemon tetras make a colorful addition to any freshwater aquarium. If you’ve seen them at your local fish store and are thinking of introducing some to your community tank at home, you may be wondering if they’re aggressive?

Lemon tetras are considered mildly aggressive by nature. Similar in size to cardinal and neon tetras, lemons can be more hostile if kept alone in a crowded tank with other bigger, more hostile fish. Stress and disease will often increase lemon tetra aggression in a captivity therefore, they should always be kept in groups of no fewer than 6 in a clean, well-maintained aquarium.

Now that you know lemon tetras aren’t overly aggressive in captive aquatic environment, let’s explore this topic further. In this article, I’ll explain if they’re fin nippers or not, whether they can live with other species of tetra fish, and why they sometimes chase each other around an aquarium. I’ll also discuss what the most aggressive tetra is and how to reduce fish stress in a community tank environment.

So, if you’re ready to learn more about the temperament and social behavior of lemon tetra fish in captivity, then let’s get begin!

Are Lemon Tetras Aggressive?

Lemon tetras are generally peacefully by nature. They don’t often show signs of aggression unless sick or under stress. Bullying by other fish may increase their anxiety level, making them more hostile towards others in a community tank environment. When kept in a large enough aquarium with plenty of space to swim about freely, lemon tetras usually do well in captivity.

Are Lemon Tetras Fin Nippers?

Lemon tetras aren’t likely to nip at the fins of their fellow tank inhabitants- under the right aquatic conditions, that is. They’re small size prevents them from being able to do any real damage to other creatures in a community tank environment. As a type of shoaling fish, lemon tetras tend to be calm and docile when kept together in groups of at least 6 with others of their species.

pair of lemon tetras

How to Stop Lemon Tetras from Fin Nipping?

Should you notice your lemon tetra nipping at the fins of its tankmates, begin by removing the aggressor and placing it in a quarantine net inside the main aquarium. While confined, treat the victim(s) with some antibiotic medication like phenoxyethanol. After a few days, the hostile tetra should be calmer and ready to rejoin the others.

Should the aggressive behavior continue, then you may need to consider rehoming the fish to a separate aquarium. If this isn’t possible, you might have to give it away to another aquarium hobbyist that also keeps lemon tetras – as the newly introduced member of an already established community tank, the hostile lemon tetra will likely become more calm, maybe even timid.

How Many Lemon Tetras should be Kept Together?

Lemon tetras aren’t just a schooling fish, they’re a shoaling fish – meaning their friendly and sociable by nature and need the company of others of their kind not just to survive, but to thrive!  Therefore, you should keep no less than 6 together in captivity. Half a dozen lemon tetras will do well in a minimum 20-gallon aquarium.

The general ‘rule of thumb’ for stocking fish tanks is 1-inch of fish per every gallon of water. By this calculation, should you intend to have a larger group of lemon tetras (at least 12 or more), you’ll need at least a 40-gallon tank since these fish are quite active and need plenty of space to swim about freely in their groups.

What Fish can Live with Lemon Tetras?

Since lemon tetras are generally peaceful and only mildly aggressive in temperament, they can coexist well with a variety of other calm fish in a captive aquatic environment. Different species of tetras (like cardinals and neon tetras) are a good choice. Small (or dwarf) danios, gouramis, and rasboras are other possible tankmate options. They can also be kept with crustaceans such as freshwater shrimp and crab.

Make sure not to house lemon tetras with large, more aggressive fish as they may get bullied and when stressed, can become quite hostile themselves. Bigger, carnivorous fish shouldn’t be kept with lemon tetras either, since they’re likely to get eaten! If you prefer to have a multi-species tank, then add like-sized fish with a similar temperament.

Why do Lemon Tetras Chase Each Other?

Lemon tetras will often chase each other around an aquarium during the breeding season. This signals a willingness to mate as the males pursue the females in what look like a game of tag. However, they may chase after other species of fish as well, especially those newly introduced to the tank. On rare occasion, they may even nip at their fins out of anxiety or frustration.

It’s often recommended not to keep fish with long flowing fins (such as guppies) in the same tank as known fin nippers. Though not as hostile as other tetra fish species like bucktooths or vampires, lemons can get fin nippy if kept in a tank alone – without others of their kind to provide safety in numbers. If you keep your lemon tetras in groups of at least 6 or more, this should help keep aggression levels at bay.

school of lemon tetras

Why are My Lemon Tetras being more Aggressive than Usual?

Should you notice your lemon tetras acting more aggressively than usually, it’s possible that the fish is sick or stressed. Illness caused by a bacterial/parasitic infection is common with this species. ‘Ick’ is the most likely culprit and requires immediate treatment with specific antibiotics so as not endanger the lives of other tank inhabitants.

Stress from being alone in an overcrowded tank with other larger fish will also increase lemon tetra aggression. For this reason, they must be kept in groups of at least 6 or more in a community tank environment. Adding plants and other decorations for cover is also recommended. The best way to keep lemon tetra anxiety to a minimum is to house them in a spacious with other peaceful types of fish.

What is the Most Aggressive Tetra Fish?

The most aggressive species of tetra fish is likely the bucktooth tetra. When placed in a freshwater tank with other smaller fish, bucktooths will often eat them. This fish is omnivorous and likes to feast on both plant- and meat-based foods, though they display no visible signs of ‘teeth’ at all! Due to their highly aggressive nature, they’re best kept alone or in planted tanks with plenty of coverage for tinier fish.


To summarize, lemon tetras are considered mildly aggressive in temperament. When compared to other types of tetras similar in size (cardinals and neons, for example) lemons can be more hostile, especially if kept alone in a community tank filled with much larger fish. Isolation, anxiety, and illness are among the main causes of lemon tetra aggression in captivity.

I trust this article has answered your questions regarding lemon tetras and their aggression levels in captivity. Thanks for reading and good luck with your freshwater aquarium hobby.

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