Have you decided to put together a fish tank to enhance your home or you already have one and you’re thinking of adding more fish? Then you need to know more about fish aggression and about the ways to prevent it.
The first step is understanding what causes fish to fight and knowing the signs that alert you that aggression is about to take place or has already happened. Of course, there are some species that are more prone to this kind of behavior, but this guide applies to fish in general.
Fish tanks are very beautiful objects to have around, especially if they feature exotic fish and a large aquarium background, but it’s important to know all the things that could go wrong in terms of the behavior of their occupants, to make sure that things remain as peaceful as possible.
You might be wondering what makes fish fight, and the answer should not be a surprise since people tend to fight for exactly the same reasons. These include food, territory, mates and so on. Most fights are related to territory and, although many species like to swim around, some like to claim a certain area as their own.
In the case of an aquarium, this area can be a corner or a piece of driftwood, a cave or some aquatic plants. No matter the spot, once chosen some fish will be allowed to pass through it, while others will not. It’s good to know that fish tend to be more territorial toward others pertaining to the same species.
One of the main reasons for which territory is claimed is to prepare a safe zone for breeding. Therefore, if another fish looks the same and is of the same sex, it will most probably be driven away. Color, patterns, and shape help fish determine if the other individual is an enemy.
Sometimes you can see a fight actually taking place, but the chances of this happening are quite small. It’s not because fish tend to hide from the human eye, but because when you are next to the tank, they are interested in the food you have to offer and their attention is focused on this.
Also, you most probably don’t have the entire day to sit and watch the aquarium, so if a fight is about to take place, there’s a good chance you won’t be there to witness it. However, there are signs you can notice once a fight did take place.
These include split fins that are a sign of damage from tussling. Also, if you can tell that some fish are suddenly hiding, this could be from fear of the tank’s bully. If there have been changes in the territory, you should look for scratches, missing scrapes or torn lips.
If a fight is about to start, the aggressor usually opens with a display such as flaring the fins or gill covers, as this is meant to give the other individual the time to decide whether to fight back or swim away. However, if space is limited within the tank, there might be nowhere to go, and the aggressor might become even more irritated.
If the situation goes on for too long, the attacked fish will try to hide as far away as possible from the bully and maybe even display muted or darker colors. In the long run, this stress can weaken the fish’s immune system and cause it to stop eating.
Just like it happens for almost all of the other animals on this planet, there’s a hierarchy that needs to be established in order for things to be peaceful in an aquarium. For this reason, if you witness a fight and your first reaction is to try and separate the individuals, this might work but only temporarily.
In the long run, it’s important to let the fish work out everything among themselves. Of course, in some cases, things can get serious, but we’ll get to this in a bit. While we’re talking about hierarchy, it’s important to know that once it’s settled this doesn’t mean it will remain like this forever.
As various individuals grow and mature, the hierarchy will also change, so even if an aquarium has been peaceful for a long time, things can surely change there as well. If the situation is not getting settled by itself, then some stronger actions need to be taken.
Since territory is one of the main reasons fish fight, if you are dealing with aggressiveness in your tank, the first thing you can do is to rearrange the decorations in a way that provides more hiding places, as well as visual barriers. Although it might seem like a surprise, once something is out of sight for aggressive fish, it’s usually out of mind as well.
For this reason, merely moving something such as a group of aquatic plants can allow two fish that have trouble getting along to establish new territories where they don’t feel threatened by each other. This redecorating solution can also work when adding new fish to the tank, as these will not be the only ones without a territory.
If nothing works, there comes a moment when a separation is in order and the first thing you need to decide is which one of the two opponents is going to be removed. If the weaker individual is removed, this can be perceived as a reward by the bullying fish, and he might focus on the next victim.
If the wounds are significant, you’ll have no other choice but to remove the attacked individual, since injured fish can become a target.
Another solution can be to put in place a net breeder and separate the bullying fish. This way, it will be able to smell and see the other fish but not attack them. This will also allow the others to create stronger territories and force the bully further down within the hierarchy.
The attacked fish can also be placed in that net to allow some healing time but without removal so that it won’t be perceived as new once reintroduced in the aquarium.