Clownfish bite their tankmates under stressful conditions. They mainly bite due to poor tank conditions, unfavorable water parameters, food scarcity, territoriality, or while guarding their eggs. Clownfish also bite humans while cleaning the tank as they feel threatened.
8 Main Reasons Why Clownfish Bite
Clownfish are usually peaceful and prefer to stay close to their marked territory.
They usually don’t get into unnecessary fights with their tankmates.
However, they’re not always peaceful. They can display aggression and resort to biting under certain circumstances.
Given below are the most prominent reasons for clownfish to bite.
1. Defending Their Territory
Territorial aggression is the primary reason for clownfish to bite.
Clownfish are very territorial and intolerant when it comes to defending their territory.
They don’t like an outsider to intrude on their territory. This is their normal behavior, even in their natural habitat.
Since clownfish feel secure in their marked territory, they feel threatened when other fish try to invade their space.
Clownfish can attack and bite the intruders to safeguard their territory and establish their dominance in the tank.
2. Incompatible Tankmates
All the tank inhabitants need to be compatible with each other to live peacefully in a home aquarium.
If the clownfish and their tankmates are incompatible, it can lead to fights.
Moreover, if you house aggressive species with clownfish, they can bully your clownfish and try to dominate them.
Clownfish can become aggressive and bite other tankmates in defense.
3. Overcrowded Tank
An overcrowded tank is another reason for clownfish to display aggression. Clownfish need ample space to swim freely in the tank.
Overcrowding can lead to space constraints. Lack of space can irk the clownfish, making them restless and agitated.
As a result, they can bite other fish in desperation.
4. Poor Water Conditions
Poor water conditions is one of the significant reasons for clownfish to bite. Clownfish need clean water to thrive.
Water quality can get affected due to an increase in ammonia and nitrite levels.
These chemicals are harmful to clownfish and irritate them.
Poor water quality can also lead to sickness and stress among clownfish.
Clownfish can become aggressive and bite due to the stress caused by unhealthy living conditions.
5. Stress
Stress is the primary reason for clownfish to bite.
Stress can occur due to poor water quality, unfavorable water parameters, constant bullying, space shortage, and food scarcity.
When exposed to such stressful living conditions, clownfish get irritated and display aggressive behavior such as biting to relieve their stress.
6. Protection of Their Eggs
Clownfish become aggressive during the breeding process.
Both male and female clownfish show parental instincts after the spawning process.
The clownfish pair are very protective of their eggs. They guard and defend the eggs from predators and other threats.
Both parents fight if any other fish come near the eggs.
They try to bite the other fish to scare them and keep them away from the eggs till they hatch.
This is normal behavior that occurs during the breeding period.
7. Unfavorable Water Parameters
Ideal and stable water parameters are crucial for clownfish to live a healthy life.
Factors such as water temperature, pH level, salinity, etc. must be in the desired range for clownfish to thrive.
If the water parameters aren’t conducive, it can stress the clownfish and impact their health negatively.
A stressed clownfish is more likely to display erratic behavior such as biting.
8. Food Scarcity
Food scarcity is another reason for clownfish to bite. Clownfish tend to fight among themselves when food is scarce.
They then start competing for the limited food and look upon the other tankmates as their competitors for food.
Clownfish can become aggressive and bite their tankmates to drive them away from the food.
Which Clownfish Species Are Aggressive Biters?
There are at least 30 species of clownfish. All of these species bite when living conditions aren’t conducive.
However, some are more aggressive than others and resort to biting more often.
Amongst the numerous clownfish species, tomato clownfish, saddleback clownfish, and maroon clownfish are the most aggressive when it comes to biting.
Do Clownfish Bite Humans?
Clownfish can bite human fingers.
It mainly happens when you insert your hand into the tank to clean it or while hand feeding your clownfish.
Hence, you need to be careful while cleaning the aquarium or performing water changes.
Clownfish don’t like being touched by humans. They will try to escape from the hand that is trying to touch them.
If they can’t escape, they may bite.
Clownfish bite humans because they feel threatened, and biting is a form of defense for them.
Does a Clownfish Bite Hurt?

A clownfish bite doesn’t hurt much or cause any major injury.
You may feel like multiple pins are pricking your finger, or your finger is scraped on sandpaper.
The good thing is that the pain doesn’t last long.
However, the bite may feel intense if you get bitten by an aggressive clownfish.
Also, the bite will hurt more if the clownfish has clenched its jaw tight and sunk its teeth into your skin.
In such cases, the bite can get deep and hurt you a lot.
The intensity of the bite also depends on the area of the hand that gets bitten.
The space between the fingers is more sensitive and may hurt more than the fingers themselves.
The best way to avoid a clownfish bite is to wear full rubber gloves or finger gloves.
Also, you can choose to keep a less aggressive clownfish species.
Ocellaris clownfish are known to be less aggressive.
The chances of them biting are less compared to other aggressive clownfish species.
Although a clownfish bite isn’t a concern for humans, it can prove fatal to other fish.
Hence, keeping a close eye on the aggression of your clownfish is crucial.
Especially when they resort to fighting and biting their tankmates.
6 Ways to Stop Clownfish from Biting
Biting is a natural instinct of clownfish to defend themselves. They can also bite if the living conditions aren’t suitable.
The good thing is that you can curb this behavior by providing a favorable environment.
Given below are some ways to stop clownfish from biting.
1. House Clownfish in A Large Tank
Clownfish are highly territorial when it comes to defending their territory.
Therefore, housing clownfish in a large tank with enough space to claim territory is ideal.
This will prevent them from getting stressed and biting other fish.
A large tank will also allow every fish to live comfortably, and the chances of other fish intruding into the clownfish territory are minimal.
The more space clownfish get in a tank, the fewer the chances of them crossing paths with their tankmates.
So the clownfish are less likely to perceive other fish as a threat to their territory.
2. Provide Conducive Living Conditions
Stress is one of the main factors for clownfish to display aggression and bite.
Hence, you should provide a suitable environment for the clownfish to remain stress-free.
You can provide suitable living conditions to your clownfish by having stable and desired water parameters, suitable tankmates, adequate nutritious feeding, and a lot of space for them to claim their territory.
A stress-free clownfish is more likely to be healthy and will not resort to biting.
3. House Suitable Tankmates
Clownfish can become territorial if they’re housed with incompatible tankmates.
Hence, you must house them with compatible tankmates to curb their aggression.
Housing suitable tankmates will also make the clownfish feel relaxed, and they will co-exist happily.
A happy clownfish will feel more secure in the tank and won’t resort to biting.
4. Feed Adequately
Adequate feeding is another way to curb the biting behavior of clownfish.
Clownfish need sufficient nutritious food to stay healthy.
You can spread the food evenly throughout the tank to ensure that all the fish get enough food.
Feeding different varieties of food can also help prevent fighting over one particular type of food as they will have numerous food options.
5. Have a Separate Tank for Breeding
Clownfish are known to guard their eggs and offspring.
The pair becomes aggressive and starts attacking other fish in the tank close to the nesting area.
You can avoid their aggression by breeding them in a separate tank.
It will allow the clownfish pair to remain calm and raise their young ones.
6. Provide Adequate Hiding Spots
Clownfish can get stressed if they don’t find a place to feel secure.
Adding caves, rocks, driftwood, aquatic plants, and other hiding spots can help reduce stress.
Such spots can provide shelter and help your clownfish to de-stress.