Molly Shimmies: Why is my Molly shaking?
Have you ever wondered why mollies tremble if you possess one? What makes them vibrate, exactly? Is their indulgence a symptom of any illness? Can it be cured? And is mollies shaking even common? I wondered the same thing when I initially acquired molly fish and saw that they occasionally tremble. But now that I’ve caught molly fish for years, I’ve finally discovered the answers to all of these queries.
Mollies shiver when they are stressed. mostly as a result of either too much acidity or water that is not the proper temperature.
Keep reading to learn everything about Molly’s behavior since I will explain everything in full below.
The Reason Why Mollies Shake?
The term “shaking molly” refers to a fish that is just twitching or shaking from side to side. There are various causes for fish to tremble. It serves as a mating ritual for some. They shimmy in an effort to entice a partner. Others see it as a show of animosity, a tactic to tell adversaries to keep their distance. But mollies are exempt from all of those explanations. They’re not meant to tremble. They should still tremble, though, just not excessively. Fish are unpredictable beings whose actions are frequently illogical. You shouldn’t be concerned about a molly that periodically shakes briefly. When the shaking continues, it becomes an issue.
That may have various reasons, including:
1. An incorrect Temperature
The incorrect water chemistry is equally as harmful as the incorrect temperature. Molly fish often prefer warm water. Shaking is only one of many symptoms you may see if you place them in a tank that is considerably cooler than is optimum.
Temperature can induce shimmying in two different ways:
- Problematic Heaters – The temperature in the tank will drop and the mollies may tremble if you don’t have a heater or if the heater breaks down. It is important to note that extreme heat is not preferable to extreme cold.
- Prolonged Transportations – Some fish are transported for such a long period that the temperature of their water drops outside of the appropriate range. That upsets the fish, but some individuals aggravate the situation by dropping the fish right into the tank when it gets there. The fish’s temperature is to be raised as their goal. Shimmying, however, can also result from that abrupt change in temperature. In cases when the new tank’s temperature is different from the place where you purchased the molly, you may anticipate similar outcomes.
2. Unsuitable Water Chemistry
Molly fish are praised for being resilient fish that can endure a variety of circumstances. They are nonetheless delicate to soft or acidic water. The Molly fish may put up with it for a while, but if the water quality deteriorates, it will begin to shake. Molly’s skin may become burned by a low pH.

3. Increased Toxins
The levels of nitrate and ammonia in the aquarium should be monitored by aquarists. When organic stuff rots, ammonia is produced. That includes leftover food from meals, dead plants, and even fish feces.
Your mollies’ gills will be burned by ammonia, impairing their capacity to breathe. If you don’t lower its concentration, it can also kill your molly fish. Shimmying is but one sign among many before it passes away.

Aquarists need to be aware of other toxic substances as well. Also hazardous are detergents. The detergent residue will poison the mollies if you don’t thoroughly clean the aquarium after washing it.
Some aquarists are unaware that the aerosols they spray in the air might dissolve in the water, making life for their fish more challenging than necessary. This typically occurs in tanks that lack a lid and are consequently inadequately sealed.
4. Your Molly is Anxious
The presence of aggressive fish, temperature and pH changes, excessive ammonia levels, a limited tank size, and insufficient feed are just a few of the numerous factors that can cause stress in molly fish. Looking for further indicators is the simplest approach to establish whether or not shimmying in mollies is brought on by stress. Fish that are under pressure frequently hide. They move quickly and wildly as they swim, occasionally slamming against the decorations and walls.
While some mollies will gasp at the surface, others will lie at the bottom. Long-term loss of appetite is another possibility. They will occasionally start to lose their color. Any one of these signs, whether present or not, indicates stress.
5. Illness
Stress can result from bacterial and parasite illnesses in mollies, and stress can result in shimmying. Mollies are compelled to brush against the things in the tank because some ailments, such as ich, make them feel uncomfortable. Such action may be interpreted as shaking by certain aquarists.
Do Livebearers Suffer from this Disease?
Shimmying used to be related to the ailment that was once known as livebearer disease. Even now, people still say that. Adding fish from brackish or hard water to freshwater aquariums is referred to by this general phrase.
Molly fish from the store is not as tough as those from the wild. The shock of being suddenly exposed to the conditions of a freshwater tank impairs their immune system. Sometimes, people unknowingly buy stressed fish from the grocery store. The store owner didn’t adequately acclimatize them before bringing them in from the wild. The outcome is that the new aquarists must deal with the consequences.

In certain places, the whole list of ailments is referred to as “Livebearer Disease.” Although it tends to generalize the scenario, you are still free to use that word. Shaking is not an illness, in the end.
Instead, it is a symptom that mollies experience as a result of the unhealthy circumstances in their tank. It is recommended to make an attempt to discover one or more of the explanations listed above if your body shakes from side to side rather than disregarding the symptom as Livebearer Disease.
How Should Molly Fish Handle Shimmies?
Shimmying is a serious issue. Your molly is unable to regulate its nerves and muscles if it is twitching, trembling, or appearing to vibrate. Fortunately, you may assist your molly by enhancing its surroundings.
Several sensible countermeasures and defenses against shimmying are as follows:
1. Set the Water Parameters Correctly
It would be advisable to keep the tank’s optimal conditions while modifying it for molly fish. It must be between 72 and 78 degrees Fahrenheit, have a pH between 6.7 and 8.5, and be between 20 and 30 KH in hardness. Your tank must hold at least 10 gallons if you want to keep mollies. In a tank that is not only tiny but also congested, it is nearly difficult to maintain the proper parameters.

In tiny tanks, the previously listed factors are more prone to change. Furthermore, fish demand consistency in their surroundings, as you are already aware. Remember that mollies do not like soft, acidic water. To boost the hardness, you can use items like Seachem, calcium chloride, and Epsom salt.
The tank’s temperature should be between 72 and 78 degrees Fahrenheit, as I previously said. That is the intended molly fish range. The temperature ought to be steady within that range, though. A terrible omen would be, for instance, if the temperature dips from 77 degrees F today to 72 degrees F tomorrow.
2. Regularly Change the Water
Water changes might be a bit challenging. A molly fish that is trembling is already under stress, and a water change might make matters far worse. It would thus be advisable to refill the water as gently as you can. I advise conducting a daily water change of about 10%. For the following several days, keep performing these water changes. The goal is to progressively enhance the tank’s conditions. Shimmying could become even more difficult if molly’s surroundings are changed too rapidly and dramatically.

3. Maintenance
I strongly advise keeping the tank tidy. If you keep contaminants out of the water, make sure to use a filter. Additionally, vacuum the substrate to remove leftovers and waste from the fish. Any dead biological substance you detect should also be removed.

That will stop the amounts of nitrate and ammonia from rising. Use minor water changes to reduce the concentration of these poisons if it increases. In a clean tank, mollies are less prone to experience shimmying difficulties.
4. Reduce Stress
As I’ve already said, stress is a big factor in mollies’ shimmies. Your molly fish will probably act properly and maybe live longer if you address the problems. In a molly fish aquarium, stress can be reduced in a number of ways:
- Keep the tank at the proper temperature. Keep pH and temperature changes to a minimum.
- Install a powerful filtration system to prevent debris from entering the tank.
- Installing pumps and air stones will help stop the spread of oxygen deficiency.
- By keeping your fish in the appropriate-sized tank, you may prevent overcrowding. Additionally, refrain from overstocking.
- Make certain the tank has locations to hide. The mollies will use plants and decorations as cover from bullies and other elements in the water they see as threats.
- Keep fish that are big and aggressive out of the aquarium. That often contains cichlids like Oscars, Discus, and angelfish.
- Because mollies school, they should be maintained in big groups. The social creatures will be content as a result.
- Feed the fish on schedule and in the proper quantities. Avoiding feeding them too much or too little might be beneficial. Give them a healthy, balanced diet that will satisfy their omnivorous cravings.
5. Think about Salt
In the community of aquarists, salt baths are particularly popular. They are used to treat fish, soothe them, and assist them in overcoming diseases. It would be ideal if you didn’t only treat ill fish with salt baths. However, you are advised to isolate it until you find the illness that is responsible for the shimmying. Pour one tablespoon of salt for every gallon of water the hospital tank holds when you do that.
6. Properly Introduce New Mollies
Avoid dumping your mollies into the tank all at once if they travel a great distance. They require some time to get used to the warmer tank environment. Because of this, I advise putting them in a different container (a bucket will do).

Small amounts of aquarium water should be added to the container (you can use the drip method). Spend an hour doing this (though, in some cases, thirty minutes are sufficient). You may move the fish to the aquarium once it has gotten used to the conditions in the tank.
Another method is to put the aquarium’s transition bag inside. The bag often floats at the top and absorbs the heat from below. A gradual equilibrium will result from that. You can be confident the fish has adapted after two to three hours.
The Bottom Line on Molly Shimmies
If you noticed that your molly was trembling, the first thing you would do is check the water’s temperature. If the temperature dropped below 72 degrees F, it is most likely the cause. To ensure the stability of the water, you need also to practice routine activities. Use a testing kit to check the water for pollutants and if the temperature is acceptable. Measure the pH and look for nitrites and ammonia. With each of those, your Molly could begin to quiver. Always keep in mind that fish shaking is only a symptom and not the real problem.