It’s distressing to watch when you see a fish bullying other fish in your aquarium. It starts with the bully fish chasing after other fish. Then you see that behavior of chasing and harassing other fish repeated throughout the day. What can you do? How do you stop fish from bullying other fish?
As a general rule, there are two main things you can do to stop fish from bullying other fish. The first is to change the layout of the aquarium by rearranging the aquarium decorations and rocks. The second thing you can do to stop fish from bullying other fish is to add more fish of the same species to the aquarium.
In this article, I will show you some of the things I have done to stop fish from bullying other fish.
How to Stop Fish from Bullying Other Fish
The trick to stopping fish from bullying other fish is to diffuse aggressive behavior. You can diffuse aggressive behavior by making adjustments to the aquarium environment and to the tank mates.
How to Tell if Fish is Bullying and Not Mating
First, before you take any action, confirm that the fish chasing behavior is indeed bullying and not mating. It’s easy to confuse mating behavior with bullying behavior. When fish mate, the male will chase after the female fish. Spend some time to observe your fish. Below are ways to distinguish mating behavior versus bullying behavior.
Find out the Gender of the Bully Fish
Is your bully fish a male or female? If your bully fish is a male, there is a chance they are mating and not bullying each other. If your bully fish is a female, then you have confirmation that the chasing behavior is a case of bullying.
What Fish is Being Bullied?
Is the bully fish chasing around the same fish? Or is the bully fish chasing around different fish? If the bully fish is a male, find out the gender of the victim fish. If it’s another male then you have a case of bullying.
If the male bully fish is chasing after a female fish, then they may be mating. One male fish can mate with several female fish at the same time so if the bully male chases after several female fish there is a chance he is mating with all of them.
Is the Victim Fish Fat and Female?
Is the bully fish chasing after a female fish with a big tummy? If that is the case, chances are high that they are mating and it is not a case of bullying. The fat female fish is likely pregnant. If the male fish is chasing after several fat female fish, then he is mating with all of them.
Is the Victim Fish Hiding and Looking Weak?
Is the bully fish chasing after a female that looks weak. Maybe its fins have been nipped. Or there is some damage on the fins or scales. Is the victim fish hiding in a corner? All this is a sign of bullying.
Flow Chart: How to Tell if Fish is Bullying or Mating
How to Rearrange Aquarium to Stop Fish from Bullying Other Fish
One of the easiest ways to stop fish from bullying other fish is to rearrange your aquarium. Rearranging your aquarium will force your fish to carve out new territories. In many cases, this puts a stop on the bullying.
Rearrange your aquarium by moving rocks and aquarium decorations around. You can also add new rocks and decorations.
Add new plants or move plants around to obstruct line of sight in your aquarium and create new territories for your fish.
How to Add New Tank Mates to Stop Fish Bullying Other Fish
One of the most effective ways to stop your fish from bullying other fish is to add more fish of the same species. Fish are social creatures and like any society, there is a pecking order. Your bully fish is the dominant fish in the aquarium. If you add new fish to the aquarium, you will be disturbing this pecking order and it will tone down the dominant behavior.
Add 2-3 new fish of the same species as the bully fish (of course don’t overstock your aquarium, only add the quantity of fish that is suitable for your fish tank size). The introduction of new fish will throw off the social dynamic in the aquarium and your bully fish aggressive behavior will tone down.
Below you will find 2 steps on how to add new tank mates to stop fish from bullying other fish.
Step 1: Acclimate the New Fish First Before Adding to the Tank
Make sure you acclimate the new fish first by letting the bag with new fish float in the aquarium water first. This will ensure the water temperature is similar before you introduce the new fish to the aquarium.
Step 2: Release the New Fish to the Aquarium
After floating the fish bag for at least 30 minutes, you can release your new fish into the aquarium. This will ensure that your water temperature is similar and you don’t shock the new fish.
What Size Fish Should You Add to Stop Bullying?
When you add new fish tostop bullying, make sure you add fish that are similar sized as the bully fish in the aquarium. If you can’t find similar sized fish, add fish that are a little bigger than the bully. You don’t want your new fish to be small because there is a chance it will get bullied.
Should You Add Male or Female Fish to Stop the Bully?
In general, it’s best to add female fish into the aquarium to stop the bullying. If your bully fish is a male, by adding more female fish, that may tone down the aggression. What you don’t want to happen is to add another male and have the two male fish fight each other.
If your bully fish is a female, adding more female fish will tone down the aggressive behavior of the bully.
What to Do If Adding New Fish and Rearranging the Aquarium Does NOT Stop the Bullying?
There is a chance the bullying does not stop even after adding new fish and rearranging the aquarium. You have to understand that when it comes to fish keeping one size does not fit all. Similar to group dynamics with humans, different personalities and different social dynamics come into play in the social balance of the aquarium.
The tactics suggested in this article to stop fish bullying may not work in all cases. When that happens, your best option to stop your fish from bullying other fish is to move the bully fish out of the aquarium.
Moving the bully fish out of the aquarium is the most effective way to stop bullying. Although, keep in mind when you do that, there is a chance a new bully will emerge from the group.
If you are keeping naturally aggressive fish like cichlids, you just have to accept that there is always going to be some kind of aggression from the dominant fish. You just have to tolerate a little aggressive behavior. However, if your fish are the peaceful type like swordtails, you really should be able to put a stop on the bullying by following the suggestions in this article.
Check that Your Fish are Compatible
The bullying of fish in your aquarium can be a result of incompatible tank mates. Are you mixing incompatible fish that should not be together in the first place? For example, if you have tiger barbs with guppies then for sure you will have tiger barbs attacking your guppies.
You should check compatibility of fish. If they are not compatible, then you should not be keeping incompatible fish in the same tank. You need to separate the fish immediately. Sometimes bullying can get so bad that the victim fish gets killed!
Good luck with your quest to stop bullying in your aquarium! It’s sometimes not easy to put a stop on the bullying of fish because you are dealing with individual fish with unpredictable behavior!