Are White Cloud Minnows Aggressive? {Top 10 Reasons Why They Fight}

Are you noticing that your white cloud minnows are getting far too aggressive? Will chasing, fin nipping or bullying lead to their death? In this article, we’ll find if and when white cloud minnows are aggressive.

Are White Cloud Minnows Aggressive? White Cloud Minnows are generally peaceful shoaling fish in groups of 6-8. The fewer the numbers, the more aggression or stress may result. Spawning behavior or hierarchical order establishing among males creates aggression that is usually short lived. 

Why Is My White Cloud Minnow Aggressive?

You may have a small group of white cloud minnows, but one of them is bullying the rest. Why is this? One possible reason is that this white cloud minnow is the largest in the group and is demonstrating dominance.

The dominant aggressor may not allow one or more white cloud minnows to eat. The weakened ones will retreat, hide or stay in a corner and die shortly after.

What Makes White Cloud Minnows Aggressive?

White cloud minnows shouldn’t behave aggressively if the tank conditions are ideal. There is a lot you can do to intervene. Before we get into tips to calm the aggression, let’s find out why this is happening.

  1. The tank might be too small.
  2. There is a competition for food.
  3. There aren’t enough hiding spaces.
  4. An aggressor needs to be removed or returned.
  5. The tank setup needs rearranging.
  6. pH, Ammonia, Nitrites and Nitrates are too high. 
  7. There aren’t enough white cloud minnows to shoal together.
  8. There are too many males.
  9. It’s time to spawn.
  10. The temperature is too warm.

1. Tank Size

10 gallon tanks work for most people with 6-8 white cloud minnows, but when you notice aggression, it may be time to get a larger tank at or around 20 gallons. The extra space will help calm things down.

2. Competition for Food

It’s fun to watch your white cloud minnows eating together as they try to gobble up pellets, flakes, brine shrimp, fruits or vegetables. Sometimes aggression results where a larger white cloud minnow chases away a particular counterpart or two and this leaves them starved or malnourished.

3. Hiding Spaces

A small sized fish like a white cloud minnow would appreciate the opportunity to retreat, hide and rest away from larger tankmates. The more hiding spaces through plants or decorations, the easier it is to thwart aggressive behaviors.

4. Remove the Aggressor

Sometimes you just need to take the bully out. Notice if you have one particular white cloud minnow causing most of the trouble.

Remove this one and decide to either redecorate and re-introduce it back or return it to the fish shop and hope they will accept an exchange. Sometimes there are 90 day exchange policies and sometimes not.

5. Move Things Around

Change the way the tank is set up from the inside out. Move around the decorations, rocks, caves and some plants if you can.

When you put your aggressive white cloud minnows back in, it’s like a fresh start. They may try to re-establish the pecking order again, but it shouldn’t last long.

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6. Water Parameters

Make sure you have no ammonia or nitrites in the tank. Keep nitrates under .25 ppm as well. You are dealing with sensitive fish that will become erratic or aggressive when they dart around after the water quality goes off.

  • pH: 6.0-8.0
  • Water Hardness: 10-15 dKH
  • Nitrates: Less than .25 ppm
  • Nitrites and Ammonia: 0 ppm

7. Not Enough White Cloud Minnows

Make sure you have 6-8 of these little guys together. White cloud minnows in smaller numbers may hide often or behave with aggression towards each other.

8. Too Many Males

Too many males will chase or nip at each other to establish pecking order or to compete for the right to mate with only a few females. Increase the females who are slightly larger, more rounded and less colorful. They will help keep things more peaceful.

9. Mating, Breeding, Spawning

The mating ritual could turn aggressive. Female white cloud minnows may require the male to show off his dominance and strength. Sometimes it’s just a dance. Other times there is chasing involved.

The female may also become aggressive during the time she is carrying eggs. She wants to defend herself and future babies. None of this aggression should cause injuries or else there are other reasons for this nonstop violence.

10. Warm Water Temperatures

White cloud minnows would like cooler water temperatures at 57-72° F. We recommend 64° F, but they can’t handle tropical waters in the mid seventies. The dissolved oxygen may thin out and your white cloud minnows may freak out.

Darting, jumping, gulping air, chasing, nipping and stress may result as the outcome of warm waters that aren’t ideal for cold water fish like your white cloud minnows.

Are White Cloud Minnows Schooling Fish?

While you may notice your white cloud minnows schooling together to swim in patterns or during feedings, they are more often shoaling. This means that they don’t need to stay in a school for most of the day.

They venture out and come together to shoal when they are happy or when they need the strength in numbers. There will be a pecking order that needs to be established. The hierarchical leader will emerge.

This white cloud minnow could be relentless in bullying, chasing or preventing others from eating. Adding more females or removing the aggressive male could help calm things down.

How Do You Know If White Cloud Minnows Are Fighting Or Playing?

If you think that your white cloud minnows are only playing, you might be right. If you see marks, wounds or abrasions, then it may be getting out of hand. Look for:

  • Marks on the body
  • Wounded or cloudy eyes
  • Pale or discoloration 
  • Nipped or rotting fins
  • Lack of appetite
  • Excessive hiding

If any of these behaviors are witnessed, then a fight or two may have caused it. Identify the cause of the aggression. See if it’s focused on one main aggressor or if the tank conditions aren’t optimal.


White cloud minnows are not considered to be aggressive fish. Male minnows may compete for the right to mate or exert dominance. Females may chase or defend their eggs they are carrying.

Stock more white cloud minnows to create a more peaceful shoaling community and definitely include more females than males if you can.


Thank you for stopping by for this article on white cloud minnows.  We really enjoy taking care of them in our aquariums. If you like, you can check out more of our articles on the variety of marine life we research and keep. Bye for now!

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.