Aggression is a normal part of fish behavior. They often fight to establish territory and hierarchy – and this behavior is vital to survival. This type of aggression is usually short-term and ends once they resolve disputes. Sometimes, however, fish bully each other, causing massive problems in a tank. So, let’s take a deeper look at fish bullying and discover seven ways fish attack each other below.
1. Aggressively Chasing Other Fish
The first way that fish attack each other is through aggressive chasing. When fish chase each other playfully, their body language is relaxed, and the target usually won’t be alarmed. If a fish is chasing aggressively, it will look tense and determined and may splay its fins and tail. The victim will usually panic and flee. Aggressive chasing will also be persistent, unlike a one-off play chase.
If aggressive chasing happens in the tank, the first thing is to ensure tank mates are compatible. Do your research when setting up a new tank or adding new members to an existing one, and avoid aggressive fish species. If fish aggressively chase one of their own species, it may be because there are too few. Schooling fish sometimes turn on each other if the shoal isn’t large enough.
2. Charging or Ramming to Defend Territory
Fish will charge and ram each other when they attack, and it’s usually to defend territory. Fish mating behavior often involves gentle ramming between a male and female of the same species at breeding time. If two fish of the same sex or opposite species ram each other, this is a sign of bullying.
Overcrowding is one of the main reasons fish attack each other, so if a fish is constantly ramming others, you must assess your aquarium capacity and research how many fish you can put in a tank. You must also ensure there are enough plants and hiding places in the tank for fish to retreat and escape from the bully. Fish may jump out of the water to escape a bully if there aren’t enough hiding places.
3. Tail and Fin Nipping
Tail and fin nipping is the next sign of aggression in fish. You may or may not see this happen, but indicators include torn or split fins or tails. Long tailed and finned species are more vulnerable to this type of attack.
Bullying is terrible for fish health and well-being, and fin nipping can cause rot and infections. Even if they are not injured, bullying makes fish more susceptible to illness due to stress. Severe bullying can even result in death, so you must address issues as soon as they arise. It can be challenging to spot the difference between playful and aggressive behavior, especially as a first-time fish owner. Observing your tank and getting to know your fish’s regular behavior can help you identify bullying.
4. Biting and Inflicting Injuries
Fish often bite each other when they attack and can cause terrible damage, especially species with sharp teeth. Like tail and fin nipping, even if you don’t catch the assault in action, sure signs of biting include wounds such as lacerations, bite marks, missing scales or even eyes.
If bullying gets to the point of physical injuries, it’s time to intervene. Isolate the aggressive fish in a breeding tank for five to seven days to give him time out. You should only isolate the victimized fish if it is severely injured and vulnerable to other fish in the tank. Use this opportunity to rearrange the tank and check your parameters. If overcrowding isn’t an issue, tank parameters are correct, and the fish continues to bully, you should consider rehoming it.
5. Marked Aggression at Feeding Time
Many fish attacks occur at mealtimes, and tiny squabbles can be perfectly conventional. If your fish constantly squabble and become aggressive at mealtimes, potentially, you may not be feeding them enough. Fish will fiercely compete with each other if there isn’t enough food.
If one fish is being particularly aggressive at mealtimes, it may be trying to prevent other fish from eating. A bully usually singles out its victim during feeding to stop him from getting food. If you have constant fish attacks when you feed pet fish, increase your fish food rations. You can also scatter food in several areas to give bullied fish a chance to feed away from the aggressor.
6. Putting on Aggressive Displays
Fish often use aggressive displays to intimidate their victims when they attack. Aggressive displays in fish include flared gills, fin displays, a color change, and rapid or erratic tail movement. A relaxed fishtail will move slowly and rhythmically.
If your fish regularly show aggressive displays or signs of stress, such as a dull color, this may be a sign of poor water quality. Fish are stressed and desperately compete for resources in poor water conditions. Follow a consistent maintenance routine and test aquarium water regularly to ensure optimum water quality.
7. Mouth Locking Outside of Mating
Mouth locking in fish is a sign of aggressive, dominant behavior and is the equivalent of wrestling in humans. Fish lock mouths to test each other’s stamina and strength. They may also lock their mouths as part of a mating ritual.
If your fish keep mouth locking, research to see if it is part of their mating behavior. If it’s not, then this is a sign of aggression. To prevent mouth locking, try rearranging aquarium plants to break down territories, and don’t keep lone species because they make an easy target.
If you’re unsure whether your fish are attacking each other, you can spot an unhappy pet fish by its behavior and appearance. A bullied fish will have a dull color and may show abnormal behavior, such as hiding and isolating. Each species has unique behavior, so research your tankmate’s typical habits to establish whether they’re bullying, playing, or mating.
