angelfish kissing or biting

Why Do Angelfish Kiss? Lip Locking in Fish

If you have more than one angelfish in your aquarium, you might have noticed them locking lips, which looks a lot like they are kissing. Angelfish are known for being calm and predictable, so this type of behavior can be worrisome for owners.

Angelfish lock lips when pairing with a mate. Kissing usually begins the mating process. However, it can also be a sign of aggression, where one angelfish will try to gain dominance over the other. Angelfish can also become aggressive if rejected by a potential mate.

Kissing is a normal angelfish behavior with a simple explanation. However, it’s crucial that you know the reasons so you can intervene if you need to. Aggressive fish are a danger to themselves and others in the tank.

Why Do Angelfish Lock Lips?

Angelfish don’t kiss in the conventional human way. They lock lips while twisting around, which makes it look like they’re locked in a romantic embrace.

As we’ve already mentioned, angelfish lock lips as part of the mating process or due to aggression. Angelfish rarely kiss for any other reason. However, if you’ve never encountered this behavior before, it isn’t always easy to distinguish between the two.


The main reason angelfish kiss is to initiate the breeding process. Angelfish who are ready to mate will select their own partner and lock lips with them to signify that they have been chosen. They may also spin around the tank as they struggle to co-ordinate their balance.

As well as lip-locking, you should notice the following signs when angelfish are ready to breed:

  • The female will develop a bulging belly and become more aggressive.
  • Paired angelfish will start to groom one another.
  • Paired angelfish will choose a spawning site and clean it together.
  • Angelfish will flash their fins and peck at each other.

Angelfish don’t mate for life. After their eggs have hatched, they sometimes look for a new mate if another fish makes a better match. This can cause angelfish to become territorial and fight with each other.


Aggression can manifest between both genders. If two same-sex angelfish lock lips, it’s because of dominance, not mating. However, aggressive behavior occurs typically around mating season, so the two are linked.

All angelfish most commonly fight over their territory and chase other fish away that threaten their home.

Females are more aggressive when protecting their offspring, while males are more likely to fight other male angelfish that attempt to steal their mate.

Similarly, if a female rejects a male’s advances, he can refuse to leave. Lip locking is a form of confrontation that usually ends with the male fish receiving a battering from the female, who will be feeling particularly aggressive while in the mating stage.

To determine the difference between male and female angelfish, observe the following:

  • Male fish have a noticeable crown, meaning there’s a difference between a male and female fish’s head shape.
  • Male angelfish are more territorial. If you notice certain angelfish acting more aggressively than others, it’s likely to be male.
  • Between the ventral and caudal fin is a tube. While hard to spot, a female’s is thicker than the males.
  • Female fish swell before laying eggs.

Knowing the above can help you determine whether your fish are getting ready to mate or are fighting.

why are my angelfish kissing?

Are My Angelfish Kissing, Biting, or Fighting?

While lip-locking is commonly associated with kissing, it’s also sometimes accompanied by biting and fighting. Frustratingly, it’s not always easy to tell until the damage has been done.

However, you must learn to spot the difference between all three. Aggressive angelfish can hurt or even kill each other if they’re left alone. Some angelfish are more prone to being bullied than others.

The next time you observe your angelfish while lip-locking, try to look out for the following things:


Kissing isn’t always a sign of aggression. Lip locking is a ritual for angelfish to determine whether they’re kissing a worthy mate. It looks romantic to us, but it’s more of a process to fish.

Angelfish also go through this process more than once in their lifetime, whenever they’re ready to find a new mate.

As long as your fish don’t start biting or fighting one another once the ritual is over, there’s nothing to worry about. Eggs are likely to appear in the tank within a few days, which means that the lip-locking process has successfully produced a match.


Angelfish have teeth. When locking lips with another fish, they sometimes bite using the teeth in their protruding jaws, which they use to grasp and yank their food.

They will bite when protecting their spawn from other fish, as well as when defending their territory. This is usually an act of desperation when the fish needs to win the battle.

Mated fish will also bite each other during the breeding process to determine whether they’re a suitable match. This is why you’ll sometimes see your fish in a prolonged embrace. They’re testing each other’s compatibility.

If an angelfish has been bitted, tears around its mouth can occur. Luckily, fish can’t feel pain like humans do, according to Biology and Philosophy. However, mouth injuries can impact a fish’s ability to eat. 


Angelfish use their mouths to wrestle. When fighting, angelfish will begin by lip-locking and biting, then once they break away, they nip at each other’s fins and swim into one another. This behavior is designed to do damage.

Injuries caused by fighting can be significant and may even lead to death. Signs of fighting include:

  • Tears around the mouth and fins
  • Missing scales
  • Damaged eyes
  • Dislocated jaws

Injuries normally come on very quickly and are relatively easy to spot. If an angelfish in your tank looks battered, it might be safer to remove it for a few days to give it time to recover.

Angelfish who have lost the fight will become scared of other fish in the tank and attempt to hide for safety. This isn’t a pleasant life for a fish to live.

How To Prevent Angelfish From Lip Locking?

When angelfish kiss during the mating process, there’s nothing you need to do. This behavior is expected, so it’s essential you don’t get involved with it or you could disturb the breeding process.

However, lip-locking that stems from aggression isn’t a good sign. It usually indicates that something inside the aquarium isn’t quite right. As a result, you may need to make some changes to calm your fish down.

To do so, follow the steps below and monitor for any changes. You might need to attempt more than one to solve the problem completely.

Change the Water Less Often

A simple way to calm feisty fish is to change their water less often.

According to Science Mag, angelfish communicate their social status through the urine and bile that’s released into the water. The chemical signals that are produced help bring discipline and order to the aquarium.

To test how angelfish behaved when these chemical signals were diluted, researchers replaced the tank with fresh water. They discovered that aggressive behavior, such as wrestling, increased as the angelfish fought to establish a new hierarchy.

When the water wasn’t changed, the angelfish settled back into their routine.

If you’re struggling with aggressive angelfish, try reducing how often you replace the water in your tank to help keep the peace and discourage destructive behavior. 

Remove Breeding Angelfish

Angelfish will fight to defend their eggs and fry from predators and dangers. They also become naturally more aggressive when mating.

To protect both them and your other fish, it’s a good idea to move the breeding pair to a separate tank, where they can produce their eggs in peace.

Similarly, if you don’t want to run the risk of breeding angelfish in the first place, only get male angelfish. Males can’t produce eggs, so you won’t have to worry about aggression caused by breeding.

angelfish kissing or biting

Reset the Hierarchy

As mentioned, angelfish assert their dominance through chemical signals. By eliminating the assertive angelfish’s territories, you’re forcing all fish in the tank to start again, thereby eliminating the domineering behavior.

Rearranging the tank’s layout also helps fish rediscover new territory, allowing some of the more peaceful angelfish to find a new spot to call theirs.

To do this, remove the most aggressive angelfish and put them in a separate tank for a few days. Clean out the tank, replacing the old water with new so that all chemical signals are erased.

When you put the angelfish back into the aquarium, monitor their behavior, and keep repeating the process with different fish until things start to calm down. If it doesn’t work the first time around, you may have chosen to remove the wrong fish.

Make Sure the Tank Is Big Enough

A pair of angelfish need a tank that’s at least 20 gallons. For every angelfish you add, you’ll need 10 gallons more. Depending on how many fish you own, you might end up with a huge tank to accommodate them.

Angelfish without enough space to swim around in will fight other fish to gain dominance. Similarly, if there isn’t enough space for angelfish to claim territory over, they’ll spend their lives fighting out of frustration by wrestling and locking lips.

If your fish always fight with each other, you may need to invest in a larger tank. Each tank should have around five angelfish to prevent both bullying and overcrowding.

Larger groups are preferred because it reduces the risk of one angelfish being singled out and bullied. However, the tank must be large enough to accommodate the school. If it’s not, you’ll have problems with overcrowding.

Feed A Sufficient Diet

Angelfish need a healthy, balanced diet consisting of high-quality dry food and meat. Every now and then, they can have blood worms, glass worms, and brine shrimps.

There’s a very fine line with how much food angelfish can have. They also don’t like to compete for it. If they have to, they become aggressive and fight other fish for what’s available.

Similarly, you shouldn’t feed them too much as uneaten food sits at the bottom of the tank, making it both dirty and unsanitary.

Feed the fish 2-3 times a day. When determining how much food to put into the tank, angelfish should have roughly 30 seconds to eat. Any more than this is too much and runs the risk of your fish over-feeding, which can lead to a range of health problems that are difficult to deal with.

Once you notice your angelfish lip-locking, you must start monitoring them to determine the cause. Angelfish that fight shouldn’t be left for too long, or one may end up killing the other. There’s always a reason for aggression in angelfish, so eliminating the likely causes will help you find a solution.