Keeping freshwater and saltwater fish in an aquarium environment isn’t always straightforward. They are sensitive creatures and easily succumb to stress if something in their habitat is off. Noticing the signs of stress and addressing issues is crucial to being a loving and responsible fish parent. To discover the signs your little friends give when something isn’t right, dive into our list of seven signs of stress in fish.
1. Sudden Changes in Behavior
One of the first things you may notice in stressed saltwater or freshwater fish is changes in behavior. So it’s a good idea to spend time watching your aquatic pets. Not only is watching an aquarium a fantastic way to reduce stress, but it’s also the best way to get to know the standard behavior of your fish. It would help if you observe their routines and swimming patterns so you can easily spot behavioral changes.
Fish behavior changes that indicate stress include shyness, aggression, hiding, and rubbing off tank surfaces. Fish will often act stressed when you add new tank mates. Adding new inhabitants creates short-term stress that usually resolves in a few days while they reestablish the hierarchy. Sudden changes in behavior may also indicate bullying or an overcrowded tank. To prevent bullying, ensure tank mates are compatible and that you have an adequate-sized tank for the number of fish you own. Do your research to discover precisely how many fish you can put in your tank.
2. Erratic Swimming Around the Aquarium
Another sure sign of stress in freshwater and saltwater fish is erratic swimming. Erratic swimming includes frantically darting around the tank, zigzagging, and swimming in areas they don’t usually swim. Stressed fish may also repeatedly swim up and down against the glass or swim in a slow, poorly coordinated way.
Injury, overcrowding, bullying, insufficient hiding places, or incompatible tank mates can cause erratic swimming. Schooling fish will swim irregularly if they don’t have friends of the same breed to swim with. The first thing to investigate if your fish starts swimming abnormally is to check for signs of injury. Next, ensure that all fish are compatible and that there is plenty of swimming space and hiding areas. You should also provide lots of mental stimulation for pet fish to prevent boredom.
3. Jumping from the Tank
Fish jumping from the tank is a clear indicator of environmental stress. Some species are natural jumpers and may accidentally jump out of the water, but fish may also try to escape if distressed. They will leap from the tank in search of a better home if the one they live in becomes unbearable due to bullying, poor water quality, or incorrect tank parameters.
If your fish regularly jump from the tank, this is a sure sign of something wrong in the environment. Jumping from a tank could indicate incorrect pH, lighting, temperature, poor water quality, bullying, or lack of oxygen. The solution is to test the aquarium water and oxygen levels, ensure tank parameters are correct, and there is no bullying in the aquarium.
4. Loss of Appetite
As a fish keeper, you’ll know the excitement of feeding time and a loss of appetite is a massive indication of stress. It’s normal for a fish to lose its appetite after a sudden stressor, such as being transported or introducing new tank mates. They will usually start eating again after a day or two.
If a fish is off its food for more than a few days, this could be a sign of illness or injury but is most commonly a sign of bullying. So, instead of focusing on food, the victim will be on high alert for its attacker at feeding time. If a fish isn’t eating, observe the tank at mealtimes to see if it’s being bullied. You may have to segregate the fish for feeding if necessary.
5. Lethargy, Such as Slower Swimming
Another tell-tale sign of stress in fish is lethargy. If a fish isn’t feeling right, they will be quiet, inactive, floating at the top, or spending lots of time alone. Lethargy in fish can be caused by illness, parasites, lack of appetite, or incorrect tank parameters such as temperature or pH. You should consult a veterinarian if you are concerned that a fish is lethargic due to illness.
6. Altered Appearance, Like Discoloration
There are many ways to spot an unhappy pet fish, and being subject to long-term stress will be very apparent in its appearance. Physical signs of stress in fish include:
- Color change
- Weight loss
- Sores or injuries
- White spots
- Fin rot
- Bulging eyes
A change in appearance can indicate many environmental stress factors such as overcrowding, incompatible tank mates, bullying, and illness.
7. Irregular Breathing or Gilling
Irregular and rapid breathing or gilling can indicate short or long-term stress for saltwater and freshwater fish. If a fish has just completed a mad dash of the aquarium, it’s standard that their gills move faster. This is the equivalent of us having deep breaths after a run. If a fish has constant rapid gill movement or is at the surface gasping for breath, this is a sign that the water is polluted or that there isn’t enough oxygen––especially if all inhabitants show the same signs and your pet fish keep dying.
Change up to 50% of the fish tank water to oxygenate it and increase the water movement in the tank. Test the water for pollutants, check that the filters work, and add another filter if necessary. Fish can drown if there isn’t enough oxygen in a tank.
Many things can stress little aquatic creatures out, and it’s our responsibility to minimize the risks. When you notice signs of stress, you must address issues promptly. If you think illness or injury is causing stress to your fish, contact your veterinarian for advice.
