Molly Fish Not Eating: What is the Solution?

Is your molly fish not eating? Has your molly fish become weak because of not eating properly? It surely can be frustrating and worrisome if a fish in your aquarium doesn’t seem to be eating anything.

Stress may be one of the main causes of your Molly not eating. This could be due to poor water quality, excessive ammonia levels, and the wrong temperature and pH. The second reason, however, can raise some red flags since your Molly might be sick with a condition like dropsy, swim bladder, or constipation, or it might be infected.

In this article, I will discuss most of the reasons why your molly fish might not be eaten.

What is Molly Fish?

The Molly fish is a freshwater fish. However, Mollies get along with other marine Species and adapt to any environment easily so they are good pets for new Aquarists. Mollies are of several types and colors. They are found in the southern United States and parts of Central America. The length of adult mollies is approximately 4.5 inches. Female mollies are bigger than male mollies. Mollies’ life span is between 3 to 5 years. Mollies are peaceful fish. They are used to living in shallow water so they swim near the top of the fish tank. Mollies are active during the day and sleep at night.                    

Molly Fish

What Does Molly Fish Eat?

Molly fish will eat a variety of food as they are omnivores. They are not picky eaters. However, they do have preferences. They can feed on both algae and meat. They can eat various foods such as blood worms (frozen or freeze-dried), tubifex worms, plankton, daphnia (etc.) Fresh vegetables such as zucchini and cucumbers are also enjoyed by mollies. You should rotate its diet between fish flakes, plant-based options, and live foods to ensure that Molly’s fish diet is balanced and highly nutritious. You should feed mollies a pinch of food twice a day. Don’t let them eat continuously for more than two minutes because this is bad for their digestive system.

Nutrition and Diet of Molly Fish

Aquarium Diet for Molly Fish

A molly fish in an aquarium without other species will be fine eating brine shrimp and flake foods. It can also eat blood worms, tubifex worms, daphnia, and plankton as long as its diet is varied. Algae is a must in Molly’s fish diet. So, it is best to grow algae in your aquarium or fish tank and provide it to your Molly fish. If you don’t have enough algae you can feed them algae wafers.

Community Tank Diet for Molly Fish

A molly fish sharing its tank with other species has to adapt its diet. It needs energy from protein-rich foods. The best types of foods are brine shrimp, blood worms, daphnia, or any other protein-rich foods. It is good to discuss molly’s diet with your vet before putting Molly’s fish in the community tank.

Molly Fish Not Eating

Related Post: How Many Mollies Should Be Kept Together?

Foods that Molly Fish Should not be Fed With

Meats from land animals such as beef and chicken should not be fed to the mollies. This is because they cannot digest too much meat protein. Some live plants are toxic for molly fish such as lilies and water lilies.

If your mollies fish is showing no interest in food, you should investigate quickly before this starvation can be fatal. Following are some potential causes that you should investigate:


A common occurrence in fish is constipation. The most prominent cause of constipation is overfeeding. This condition can prevail by the purchase and feeding of poor-quality food items. The feeding method can be at fault too. Some dry foods can expand in your molly’s stomach blocking the digestive tract. A constipated molly fish will either eat little or no food. A molly fish is likely suffering from this condition if it swims slowly, is bloated, or hides in the bottom of the tank.


Molly fish are open to many diseases, infections, and parasites. They lose their appetite whenever they fall sick. There are various illnesses that have different symptoms. For example, irregular and unstable swimming can point to swimming bladder disease and dropsy. Fuzzy growths can point to fungal or bacterial infections.

molly stress

Low water quality

A properly cycled tank with appropriate conditions should be provided for molly fish. The pH, temperature, and hardness should be kept in the acceptable range. If your mollies are not eating, it is possible that the quality of the water has dropped. It can be intoxicated with dangerous levels of ammonia nitrates or copper (etc.) If you have tried to clean the tank, but the mollies are still not eating, then the changes were too drastic. Suddenly changing the environment can induce stress in the molly causing a loss in appetite.

Appetite Loss

Water Temperature

The wrong water temperature can not only induce stress but also slow down molly’s metabolism, making it lethargic. As a result, it stops eating and spends more time sitting in one place. Hot water can cause oxygen deficiencies while cold water can cause the molly to become lethargic.

Aquarium Temperature is Too Low

New Habitat

Mollies that are not accustomed to a tank go into hiding. This is because they’re new to the habitat. This will induce stress making the molly lose its appetite. However, this condition is not a problem as you have to wait for the molly to get used to the new environment.


Pregnancy makes mollies lethargic due to which they spend less time swimming and stop eating as a result.

As soon as fish Pregnancy is Apparent

What to do if your Molly Fish is not Eating?

Following are some solutions you can use so that your molly fish starts eating again:

Adjust the Environment

It should be made sure that the tank is in the best condition possible. Water temperature should be adjusted (72 to 78 degrees) and hardness should be kept within the appropriate range (15 to 30dGH).  You should put an Automatic aquarium heater and a thermometer in your aquarium or fish tank. If the temperature of the aquarium or fish tank fluctuates or the temperature is low then bacterial diseases affect the fish. If you want to increase the temperature increase it slowly because Molly fish don’t like a sudden change in temperature and it also causes stress in Molly fish. Stress is the main factor that causes diseases in fish.

Regular Maintenance

Regular water changes should be made to help the tank stay clean. An efficient filtration system that matches the size of your tank is needed. It is best to replace 15 to 20 percent of water weekly. You should check the water quality frequently.

fish tank maintenance


Planted tanks provide hiding places for the molly fish. Hiding places are important for mollies as they have to combat stress and large fish in a community tank. The absence of hiding places can induce stress making the fish lose their appetite and stress also decreases the immunity level of fish making them prone to different diseases.

Amazon Sword

Tank Mates

Mollies are peaceful but show aggression when the tank mates are aggressive or the tank or aquarium is overcrowded. For this reason, you should keep Molly fish with friendly fish and plenty of space to live and swim freely. Mates which are less aggressive towards mollies should be kept such as rasbora and zebra danios. Plants should be added to the tank even if Molly’s tank mates are peaceful because Molly fish likes to hide in plants and other ornaments.

Number of Mollies

Mollies are schooling fish and have a peaceful and social nature which helps them to survive in groups. A greater number of mollies is good as it will make them feel confident and secure. Moreover, they will get rid of stress easily. The number of females should be greater than the number of males. Otherwise, the males will harass the females. It is best to put four females and one male. This ratio is best for Molly fish.

Properly Introduce New Mollies

Fighting Diseases

There are some freshwater diseases that affect mollies. The most prominent illnesses are Ich, Velvet, Fin, and tail rot. These diseases are caused by bacteria, parasites, and infections. As prevention is better than cure we should try to prevent diseases. So that our Molly fish will not suffer.

  • Clean your fish tank or Aquarium regularly
  • Gravel your aquarium or fish tank.
  • Water quality should be good.
  • Check the water quality regularly.
  • Maintain the temperature of your aquarium or fish tank.
  • Your aquarium or fish tank must be properly filtered and aerated.
  • Avoid all those things that create stress in Molly’s fish because stress makes Molly’s fish immunity weak.

When the fish is sick it has to be treated.  You should also consult a vet for a fast recovery. Some important things you should do are:

  • Put salt in an aquarium or fish tank approximately 2 teaspoons per gallon of water.
  • Increase the temperature of the aquarium or fish tank.
  • Clean your aquarium or fish tank.
  • Check the symptoms, identify the disease, and give proper medicine to mollies.
  • Give mollies highly nutritious food.

Adult mollies can survive two weeks without food but molly fry can only last two to three days. The conditions in the tank can also affect this.

The Bottom Line On Molly Fish Not Eating

In conclusion, molly fish is a peaceful fish that can be kept in an aquarium. They are easy to keep as long as they have their basic needs such as clean water, proper food, and temperature. You should give plenty of space for Molly fish to swim. Mollies don’t like crowded places. Mollies are stressed with aggressive tank mates. The best thing about mollies is that they are not easily stressed. However, a time can come when your molly stops eating. The most common symptoms of a sick fish are lethargy and loss of appetite. Making Molly fish happy is not difficult. In this article, I covered most of the reasons why your molly fish might not be eaten. Get the knowledge and make your Molly fish happy and healthy.

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