Generally, fish swim at different depths of the fish tank. Some species prefer to inhabit mainly the lower part, while others are more likely to spend their days in the intermediate or upper regions of the fish tank. But then why do my fish stay on the surface of the aquarium?
One thing you don’t want to witness, however, is a fish that is spending most of its time near the surface – perhaps panting – and in apparent distress.
How does fish breathing work?
A fish can remain close to the surface because it is trying to breathe more easily. Remember, these animals breathe dissolved oxygen in water – not oxygen that is already combined with the H2O molecule.
Naturally, dissolved oxygen levels tend to be much higher on the surface, where the interaction between air and water occurs. A fish that is not receiving enough oxygen will try to compensate by gravitating toward this area.
Similarly, you may notice your fish approaching the bubbles of the air pebbles or other decoration that produces bubbles.
What to do if your fish are on the surface all the time?
That’s going to depend. A single fish may not be getting enough oxygen due to a problem with its gills, such as worms, parasites, or injuries.
However, if you notice that several fish are trying to breathe on the surface, or if they are all spending most of their time in this region, it is likely that something is wrong with the conditions of their habitat.
Above all, be sure to check and correct the following items to ensure the health of your pet.
Overcrowding
An overcrowded fish tank, with many fish polluting the water and competing for the same air supply, can cause low oxygen levels.
For freshwater fish, start with the general rule of “one cm of fish per liter of water”, but keep in mind that this reference point does not take into account the fact that some fish have larger bodies and some varieties are more demanding than others.
Use this rule only as a guideline when calculating the appropriate fish tank size. Do additional research or talk to experts to identify the ideal size of the fish tank for the species you are planning to acquire. Also, be sure to calculate the size of the adult fish – not the young fish of a few cm that you saw in the store and that you are thinking of taking home.
Another cause of low oxygen levels in an aquarium may be the lack of surface area. Instead of just considering the volume of your fish tank, think about buying one with a larger surface area – that is, one with more air contact.
Two aquariums can have the same volume, but if the shape of one of them allows it to have more surface area (shallower than high), it will probably have high levels of dissolved oxygen in the water, and that’s always good.
Lack of aeration
If your fish stay on the surface of the water, keep the fish tank water moving at all times. The movement helps maintain good quality and a good supply of dissolved oxygen throughout the fish tank.
A good quality filter is critical for waste removal.
The decorating elements that produce bubbles, such as firecrackers and air stones, can also add small amounts of oxygen, but are more for decorative purposes.
Inadequate temperature
Water temperature can also play an important role in oxygen concentration. However, warm water contains less oxygen than cold water, so during the summer months, keep an eye on the temperature of your fish tank.
Avoid leaving them on the surface for long periods of time by regulating the water temperature with a heater or cooler. Also remember to check what the ideal temperature for the species you are creating, this can be a crucial factor when keeping the water at the highest temperature or not.
Species that should breathe on the surface
Finally, keep in mind that some species – such as bettas and gouramis – breathe air from the surface. If your fish tank is home to one of these animals, be sure not to confuse normal behavior with an oxygenation problem.
As we can see, some problems can be solved very easily, such as adding an air pump to the fish tank, or lowering the water temperature, depending on the species.
Another alternative is to make the outlet of the fish tank filter generate a lot of movement in the water column, thus generating oxygenation necessary for the fish.
Anyway, all these alternatives require a little study and knowledge of the needs of each species. So if your fish still stay on the surface of the fish tank and you have any questions, leave your comment! We’ll try to help you!
