Why Do Danios Chase Each Other? 5 Reasons Explained

Why Do Danios Chase Each Other?

Danios are non-aggressive freshwater fish, but sometimes they could exhibit some aggression or at least what looks like aggressive behaviors which include chasing each other and also what looks like fin nipping. If you know them as peaceful fish that school a lot and you happen to see them exhibit all these behaviors, you might be wondering if they are really peaceful as they are being said to be, or you might be wondering why they are doing that. This article will answer your questions and I suggest you read it to the end.

Why do Danios chase each other? Danios are social fish and they play a lot with their kind, they usually chase each other when they play.

They are schooling fish that don’t normally survive individually nor even in a small group, but in a large group of not less than 6.

They are considered to be very active and fast, that’s why they need a lot of space in their tanks, despite being small in size.

Because they play a lot, they normally chase each other and some of their activities might look aggressive to anybody watching them, but in the real sense, they are not aggressive nor nipping at each other’s find, but playing.

There are other reasons why they chase each other and we will look at all of them in a minute.

Why Are My Danios Chasing Each Other?

1. When they are few in a tank: One of the common reasons why these fish could become aggressive and will start attacking each other and other fish in the tank is when they are few in their tanks.

This might sound like a surprise, but it is a fact that all schooling fish like them could get aggressive and uncontrollable when they are just a few in a tank.

This happens when they are less than 6, that’s why it is always advised to keep them in their numbers which is a minimum of 6.

2. Poor Water Quality and wrong parameters: Every animal deserves a nice and comfortable living condition and when they are not living in their ideal environment, they might change.

Keeping Danios in dirty water, cold water, Uncycled tank, small tank, etc they will only end up being very unhealthy, stressed, and aggressive to each other and other fish, hence they will start chasing each other and might be nipping at each other fins and tails.

Dirtiness breeds toxins such as Ammonia, Nitrite, chlorine, etc which will end up frustrating them and might even kill them in the long run.

So, get a filter to help keep their tank clean and do at least a 30% change of water every week.

The cold temperature could frustrate them too by depleting their oxygen, etc, so get them a Heater and keep the temperature between 65-75°F.

3. They might be playing: As I explained above, these are very active and social fish, hence they live and move about in groups.

Sometimes they chase each other not because they want to fight or do any harm to each other, but because they are just happy and healthy and they do play a lot when they are happy and healthy.

So, if they are doing this, sometimes you don’t need to worry about it as it is very normal.

4. They establish a hierarchy: We all know that all schooling fish do establish dominance when they are many and they sometimes achieve this by chasing each other about, especially the alpha male chasing the other males.

Again the males might be chasing each other to have the best females all to themselves and it is very normal.

5. The males do chase the females when they want to reproduce: This is very normal for them, and it is one of the reasons why you might see yours chasing each other.

When the males notice that the females have eggs, they will start chasing them until they get tired and release their eggs which the males will now fertilize by releasing their Milt on the eggs.

These are the 5 reasons why Danios chase each other.


Danios are peaceful fish, unless they are not comfortable, they might become aggressive, so they ain’t aggressive unless you make them, that’s why you might see them chasing and nipping at each other’s fins.