Fish in a tank do chase each other for a variety of reasons. It takes some experience to find out whether they are chasing for playing or fighting. If fishes are happy in the environment that you have created for them then obviously they will spend time playing with each other.
However if they are under stress then it is likely that they will try to spend the stress by chasing for fighting. Fighting in fish can lead to death as well and should not be taken lightly. Since a fish tank is a confined area fish that are weaker will have no way to “run away” but to surrender themselves to bullying and finally die.
That is why to avoid stress always make sure that you follow rules when you set up a tank. The number one rule to follow when you want happy fish is to avoid overcrowding commonly known as “overstocking” of fish.
When there are plenty of fish, chances of fighting with each other are always going to increase. Don’t buy fish just because you have space or you are getting them at a cheap price. Many new fish tank owners give preference to visual beauty of the fish and buy them because they look beautiful in fish tank. But this can lead to deaths if your newly bought fish is not compatible with existing ones or with the other species that you are buying.
When you set up a fish tank you are reproducing the natural world in a confined glass box. That is why you must follow rules of the natural world where these fish are born and live a happy life without stress.
When fish chase each other you’ll see the following common behaviors being followed by them.
1) Chasing
2) Nipping
3) Biting
4) Pushing
5) Playing
Fish will follow these behaviors for a variety of reasons and we are going to look at these here.
Table of Contents
For Mating
You must have seen men and women chasing each other all the time but fish do this too. The very common reason for chasing is for mating. It’s a natural drive and because of the inbuilt instinct of reproduction.
Problem arises when two male fish start fighting over a single female in the tank and these fights lead to death of either one. To avoid such fights you must maintain a male to female ratio in the tank.
To avoid fights between males for mating purposes what you can do is introduce more females for every male fish. You can follow a ratio of 3 female fish per 1 male fish. This will reduce fights and chasing events in the tank as the males will get distracted when they see more females in the tank.
It’s not just that males chase females; sometimes you’ll also see female fish chasing a male fish for mating purposes and is considered a normal instinct. If a male fish is chasing a female for mating but if she is not happy about it then she will chase the male as a defense and make him run away.
Fighting for food
Fish also chase each other for food. If your tank is overcrowded and food being introduced is less in quantity then obviously some fish are going to starve for food. If this happens you’ll see fights over food and chasing accidents.
Always see to it that your tank is not overcrowded with fish and depending upon the number of fish, correct quantity of food is being fed. When I say correct quantity I mean, not less and not more.
If you feed too many food particles the uneaten food gets settled down at the bottom of the tank and gets decayed. This decayed food gets converted into ammonia, which is extremely harmful for fish.
Bullying
Just like other animals community bullying is a major problem in fish community as well. The truth is this should not be called as a “problem” because “survival of the fittest” is the rule of the natural world and we have to accept this fact.
In a fish tank though since the area is confined in a glass box the weaker fish don’t have space to run away to protect themselves from bullying and as a result of this they go under stress. Stress of any kind in fish leads to serious disease if not treated.
When you see fish chasing each other make sure to observe if they are biting or nipping fins. If you see such violent behaviors immediately transfer the stronger or the weaker fish in a new tank and save life.
Establishing Territory
Fish chase each other when other fish are trying to take over their territory in fish tank. Just like other animals fish love to form their own space in the tank. To make it easier the first thing you must follow is to have less fish and avoid overcrowding. This will allow each fish to have a bigger space of their own.
This could be in the form of smaller hiding places behind plants, decorations, certain corners of the tank etc. If they see other fish entering this area for a longer amount of time they’ll chase each other to establish their dominance.
Fish Compatibility
Many new comers in this fish keeping world make a big mistake of buying fish that look beautiful visually in the tank without checking their compatibility. Not all fish species go well with each other.
If you buy pairs with wrong compatibility, then they will fight badly over survival and this can lead to death. When you buy fish species in pairs always check their compatibility and always follow male to female ratio as well.
If there are too many male fish but fewer females then males will fight with each other for mating over the female fish. As a general rule keep 3 female fish for 1 male fish so that while swimming in the tank when the male starts chasing a female he gets distracted when he seen another female available for mating and stop chasing the first one.
Stocking a fish tank is more than just buying a bunch of pairs and inserting them in a new tank. You must also look for these intricate possibilities of what really happens when they start living together.
Size of the fish
When you buy fish for your tank, it’s possible that they are smaller in size. But you must also consider how big they grow over a period of years from now. If a particular species of fish becomes too big for your tank volume then obviously they will also require more food and will dominate other fish in the tank. Just like “fish compatibility” volume of the fish itself plays an important role here.
While picking up species see to it that they all grow to medium size in the next few years. Not only will they require more food but more space as well. Shifting them to a new tank will be a costly affair and will require good amount of planning from money point of view as well. Goldfish and Koi grow in size over a period of years and will need more space.
There could be four different possibility of “chasing” events in any fish tank and we are going to look at theses one by one.
Male fish chasing another male fish
When a male fish is chasing another male then most of the times this could be for
1) Bullying
2) Establishing territory
3) Dominance
In such cases the weaker fish could go under stress and this stress if not controlled can lead to a serious disease. If you see male to male chasing events frequently in your tank, then it’s the time to take action and remove either of the fish from there to a new tank.
This could happen if you have not checked compatibility of fish before buying them or your tank is over crowded with too many males. Male fish can dominate other male fish if
1) The weaker ones are eating too much food and the stronger one is getting less of it.
2) Other males are chasing or are trying to mate the same female.
3) Other weaker fish are trying to enter the territory of the stronger fish.
Male fish chasing another female fish
This is considered perfectly normal and most of the times is for mating purposes. When you see male to female chasing you can shift both to a new tank and let them reproduce in the new tank. If the female fish gets pregnant she will probably give birth to new ones in the same tank and your established tank will get filled with hundred of fries. Managing this tank of hundreds of babies can be a big nuisance.
Female fish chasing a male fish
Yes, females also chase a male fish and this could be for mating purpose also. If a female is happy or attracted to a male fish then she will try to encourage the male to reproduce with her and chase him.
The second reason could be if a female is not happy with a male chasing and troubling her all the time she will try to make him run away and leave her alone in her own way.
Female fish chasing another female fish.
If you see a female fish chasing another female then this could be just for playing or fun most of the times. Just like male fish chase another male for bullying or establishing dominance, females will also try to establish their own space in the tank and chase other females to mark their own space in the tank.
Actions you should take
Chasing should be considered a serious event when you see fish attacking each other and causing harm. This could be in the form of
1) Biting
2) Nipping fins
3) Pushing
Such violent actions can cause injury which leads to fungal infections. Many fish have delicate fins and other stronger and dominant fish first attack these fins by biting and nipping.
If these delicate fins get ripped they are likely to get an infection or get tangled in decorations or plants. In such cases if not treated can lead to serious disease that can spread to other fish as well.
That is why if chasing accidents are happening between male fish then this is a warning sign that some serious action must be taken. This action could be in the following form
1) Removing either the stronger or the weaker fish and shifting him to a new tank
2) Introduce new fish by checking compatibility
3) Check if the tank is overcrowded and remove some from the tank and shift them to new tank.
Avoid conditions that produce stress
The root cause of all chasing activity except playing and mating is stress in fish. As the owner of the fish tank it’s your duty to reproduced exact conditions that are found in natural world where these fish live a happy life.
When fish are under stress they try to find a comfortable environment by changing their location in a big pond, but this is obviously not possible in a confined area like a glass fish tank. Eventually weaker fish surrender themselves to the stress and become ill. This illness or disease can cause death as well.
That is why when you are starting out with a new tank study the necessary requirements of a fish tank from various points of views like
1) The minimum equipment required
2) Fish compatibility
3) Basic and advanced Water chemistry
4) Cleaning and maintenance schedules to be followed
5) Fish food options
6) Fish diseases
You don’t have to study everyone at once but start exploring various angles and the minimum expertise and knowledge with which you can start. With time you’ll gain experience and confidence in handling panic situations and become an expert.