Many betta owners are keenly aware of how active their fish are. But, compared to other fish, your betta may seem more lethargic or like to sleep more. Is this normal? How can you tell if your fish is sleeping normally or something is actually wrong? Here are some signs you might observe.
What is Sleeping in Bettas?
All fish, including bettas, sleep. They don’t require a soft bed or even eyelids, and most fish don’t sleep like you or your fluffy pets. Instead, fish sleep in a state of low metabolism. Most of their brain function is shut down, but they still have the capacity to respond to any immediate threats. A fish’s specialized organ for sensing water movement and vibration, the lateral line, is a quick reacting organ that can alert a sleeping fish to any oncoming danger.
Your fish will sleep when it is dark, so an appropriate photoperiod with light and dark cycles is critical to all indoor tanks. Typically 10-14 hours of light per day is appropriate for tropical fish. If you are unable to turn the lights on in the morning and off at night, an automatic light timer is an important addition to your system. Some lights will even have a morning and evening period where the light slowly changes from dark to light and vice versa. Your light period should match your local light and dark cycles unless you live at a very high latitude.
When your fish is asleep, they cannot close their eyes since fish do not have eyelids. Eyelids in many terrestrial animals are important in lubricating the eyeball, and when you live underwater, lubrication is all around you. Sleeping fishes may wedge themselves in a crevice or a cave, or if they are a betta, find a calm, flat sleeping spot, such as a leaf or décor item. Bettas really like to sleep in large flat leaves, such as stick-on betta leaf hammocks commonly available at most pet stores. Bettas without leafy décor may find a spot on top of a flat rock or even laying on the bottom of the aquarium substrate.
Why Do Bettas Sleep a Lot?
In the fish kingdom, bettas fall in the more lazy spectrum, requiring longer rest periods than many other pet fish. Their long, ornate fins take a lot of energy to pull through the water, a feature that many other pet fish do not have. Some fancy varieties of goldfish may also have long fins, and these fish require significantly more energy for swimming than their short finned counterparts, especially if they have stout, compact bodies.
Imagine trying to swim in a pool wearing a ball gown. It can be a very difficult way to swim, pulling around a lot of material that does not help you swim. This is very similar to a betta fish dragging around a long ornate tail. In order to survive, they take extended rest periods in between meals.
Temperature is critical to proper fish activity, including metabolism, growth and immune function. Fish of various species have a certain optimal temperature that they function best at. For bettas, this is a tropical temperature around 78-82F (25-28C). Your betta tank will require a heater to keep the water at the best temperature for their activity. If your water is too cold, your betta will be resting more than usual just because they will have a slower metabolism.
Signs of Increased Sleeping in Bettas
Your betta's activity level can vary widely even within a normal range. It is important that you do not compare your betta to any fish you have owned previously or any fish online. Your betta may only be active during meal times, or may zip around their tank constantly. There is no percentage of swimming vs. sleeping time that is "normal" for all bettas.
It is critical to evaluate your betta's change in swimming vs. sleeping over time. All new fish will likely hide or rest more often than fish that have been in their tanks for awhile. A normal activity adjustment period may take a few days or a few weeks for a new fish to settle in.
If you are concerned about your fish sleeping more than usual, start a log and take videos to compare to various time periods. Pay close attention to meal times and how your betta responds to food being added to their tank. These notes will be very helpful in determining the cause of your betta's increased sleeping. Monitor your fish's body condition to see if it is gaining weight, which may be a cause of it becoming less active.
How to Stop Increased Sleeping
If you have logged an increase in your betta’s sleeping time, the first thing to check is your water temperature. Remember, bettas need warm water and their aquarium will require a heater. Do not rely on stick on thermometers, but rather use an in-tank thermometer. This will give you the most reliable temperature. Digital thermometers may be more convenient, but do not have the longevity of standard glass thermometers.
If your betta’s water temperature is appropriate, and all the other water parameters are in the normal ranges, it is time to evaluate their diet. If their container of betta food is older than 6 months, the vitamin C content has severely diminished and will require a replacement. You should be feeding your betta two to three times a day and giving enough pellets that would theoretically fit into one of their eyeballs. Supplementation with frozen foods is fine for bettas, provided that most of their diet is pellets with a complete nutritional profile.
If your betta is getting enough of a high-quality diet and has a warm tank with good water quality, but is still sleeping excessively, it is time to call your aquatic veterinarian. Common betta diseases, including mycobacteria, commonly known as fish tuberculosis, may be causing your fish to be more lethargic and sleep more. The sooner your fish receives veterinary care, the faster the recovery will be.
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Bleckmann H, Zelick R. Lateral line system of fish. Integr Zool. 2009;4(1):13-25.