Glass Surfing: Why Do Fish Swim Up and Down the Glass?
Why Do Aquarium Fish Swim Up and Down the Sides of the Tank?
Fish exhibit many behaviors that tell us how they are feeling, and glass surfing (also known as pacing) is one of them. This is when fish constantly swim up and down the sides of the aquarium glass. One reason they do this is stress. It could mean they aren’t happy in their environment, for one reason or another.
As aquarium keepers, it is up to us to examine the situation and determine the cause of their stress. There may be something we can change in their environment that will help them to calm down, such as improving their water conditions.
However, in many cases, the issue comes down to poor stocking decisions or tank size choices. This is why it is so important to research the needs of any fish you intend to stock before you even bring them home.
Stress is one of the biggest reasons aquarium fish die too soon. Watching out for signs of stress and taking action to reduce it can go a long way toward keeping happy, healthy fish. In this article, we’ll take a look at some of the common reasons fish glass surf and what you can do about it.
Poor Water Conditions
Maintaining clean, healthy tank water one of the most important things you can do to make sure fish remain stress-free. Waste chemicals build up in all tanks, and every fish keeper must take steps to reduce them. Of course, this means properly cycling your tank before you add any fish. Unfortunately, this is a step many novice fish keepers rush through or skip completely, and it may come back to haunt them.
Once an aquarium is up and running, it is vital to perform frequent water changes. This dilutes any waste chemicals, and if you learn how to use a gravel vacuum you can clean the gravel and change the water in one shot.
If your water parameters are healthy your fish are less likely to show signs of stress such as glass surfing. If you aren’t sure if your tank water is healthy it is easy enough to find out. You can take a sample to your local fish store and they can test it for you. I suggest having your tank water tested as well as the water straight from your source.
There are also inexpensive test kits you can use at home that will let you know how healthy your water is in a matter of minutes. There are a few options on the market, but I've always preferred the . It’s very easy to use and it tests for pH, high range pH, nitrite, nitrate, and ammonia. The kit lasts a long time, even if you test daily. API Freshwater Master Test Kit
Overstocking and Overfeeding
Overstocking is another problem that may lead to stress behaviors in your fish, and this issue is closely related to water quality. Along with your fish, there are millions of tiny microbes that live in your tank. That’s a good thing. They help to process the waste created by the fish, and because of them, it is easier to keep the tank water healthy.
This is why we cycle a tank—to allow the healthy microorganisms to increase in number. Ideally, the microbe colony in an aquarium will be able to break down the waste created by the fish. But when we have too many fish, things can get out of whack.
Put simply, more fish create more waste. When the bioload exceeds the ability of the microbe colonies to process the waste, the water quickly fouls. The same can happen with overfeeding, where there is too much uneaten food decaying in the tank. These conditions can lead to excess algae buildup or even a pest snail outbreak. More seriously, they can make your fish ill.
Your fish may also feel physically crowded in an overstocked tank, which can result in them pacing the glass. Fish need space to swim, and when a tank is crammed with other fish or decorations it can be stressful for them. Unlike in the wild, there is nowhere for them to go if they don't like their current location.
About Schooling Fish
So, to prevent your fish from glass surfing you’ll do everything you can to keep their water clean, so they don’t get feel stressed and get sick. And, you’ll avoid overstocking so they don’t feel overcrowded. The second issue is very important for semi-aggressive fish like gouramis, angelfish and bettas. Too many other fish in their territory can make them downright ornery.
But some fish prefer to have other fish around, especially other fish that look like them. Some, like guppies, platies and mollies, are best kept in groups with two females to every one male. This gives them the social interactions they need without undue stress on any one fish.
For other fish, more is better. These fish live in huge schools in the wild, with numbers ranging in the dozens, up to the hundreds or even thousands. This natural behavior is very important to consider when stocking fish in the home aquarium.
This is yet another reason why it is so important to research the fish you intend to purchase. Schooling fish need to be in groups of six or more, and that includes obvious species such as neon tetras and not-so-obvious ones such as corydoras catfish.
While they can make excellent community fish, schooling fish that don’t live in large enough schools tend to exhibit unnatural, stressed behaviors such as glass surfing or, worse, occasional aggression. I always recommend a minimum of six, but more is better if you have a large enough tank.
Incompatible Tank Mates
Just as it is important to make sure your fish are living with the right tank mates, it is equally important to ensure they aren’t living with the wrong ones. A bullied fish is under constant stress, and you may find them pacing the glass or hiding all the time.
Once again this comes down to understanding the fish you intend to stock. For example, if you intend to have tank mates with a betta fish you need to put some effort into researching your best options, and how to do it correctly. In some cases an aggressive betta may cause stress for other fish in the tank. In other cases, the betta may be picked on, and he’ll be the one exhibiting signs of stress.
There are less extreme examples. If you keep a pair of male gouramis one may bully they others. A pair of angelfish may or may not get along, and one may lash out at the other, or at other tank mates. Fin nippers like tiger barbs may stress angelfish.
Once again, doing the research necessary beforehand can help you understand how your fish might interact, and if they are a good match.
Finally, the size of the tank itself is a big reason a fish may be stressed and unhappy in its environment. I can’t tell you how many messages I get from people saying they have a betta in a two-gallon tank and he seems unhappy, or they have a completely inappropriate array of fish in a five-gallon tank.
Without enough room to swim and live a fish will be stressed. Any animal confined to too small of a living space is going to want out.
To make matters worse, small tanks are harder to keep clean, and it is harder to maintain healthy water quality and proper temperatures. If you intend to have more than a few fish these problems are exacerbated even further.
All of the issues listed above are magnified in small tanks. I always recommend at least a five-gallon tank for a single betta fish, and a ten-gallon tank for tropical fish. Sometimes this alone is all it takes to solve problems with stress behaviors.
What to Do About Glass Surfing
Occasional glass surfing isn’t anything to worry about. There are even some instances where pacing the glass is normal and expected, such as when a fish is new to its environment, after you perform a water change or other major tank maintenance, or when people are standing near the tank and the fish may expect food.
But maybe you’ve gone through the situations above and don’t believe any of them apply to your situation. Your water perimeters are good, your tank is the appropriate size and not overstocked, your schooling fish seem happy and are kept in the appropriate numbers and there are no aggressive fish in the tank. What now?
It’s important to remember that fish act in all kinds of unexpected ways in an aquarium. You can continue to experiment with ways to relieve what you believe may be causing the stress, but don’t stress yourself out trying to get to the bottom of it. Then you’ll be the one climbing the walls!
Make the best decisions you can for the fish under your care, and learn along the way. That’s all any of us can do.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.