Why is My Pet Fish So Fat?

Why is My Pet Fish So Fat?

If your pet fish is fat then you should find the main cause of this problem. In this article, we have added 8 main reasons that can make a pet fish fat.

Why is My Pet Fish So Fat? Your pet fish can be fat when they are suffering from sicknesses such as dropsy, constipation, Hexamita, tumors, and also due to poor maintenance of a fish tank, when female carrying eggs, and overfeeding. 

Why is My Pet Fish So Fat?

Some fish becomes too fat or get bloated. Their fatness not only means that they are healthy. Sometimes it is an alarming situation for your fish because they become obese due to different diseases. 

You can sort out these illnesses and swelling by following some precautions; always clean their aquarium, offer them the right amount of food, clean water. When they suspect any disease, quarantine that fish from others. It will stop the diffusion of the ailment and save other fish. 


Every pet owner’s first consideration is dropsy when their fish become obese or bloated. A swollen or enlarged abdomen is the main sign of dropsy. It causes the eyes to the knob and the body to bulge.

This ailment is caused by absorbing a high amount of H2O but fail to discharge that amount. It is such a worrying and dangerous disease that can kill your fis, but some treatments help save your fish.

Fish suffering from dropsy have a high risk of morality, slightly options can work better. When you suspect that your fish has dropsy, immediately separate it from other fish or tanks. Make sure aquarium water is clean and fresh. Now add one teaspoon salt for a 1-gallon ratio, also give them fresh food. 

Fish Carrying egg

The foremost or common reason for fish inflating is they might having an egg. You first require to know either your pet fish is male or female. If your fish is female and she is not excessively heavy from the whole body, their fatness merely occurs on the abdomen.

Female fish have red or black dots under the stomach this spot; matures bigger and darker when the fish is pregnant. They feel difficulty while moving or swimming.

Another most common indication is they hide behind foliage, plants, and decorations in the tank. There is a high possibility that she is pregnant or carrying an egg.

If you become sure that your fish is pregnant, you should give her proper water, food, and aquarium condition. The Ph level and temperature should be accurate. 

Viral infections

Viral or bacterial infections cause fish to bloat. These internal infections can damage their digestive system and can weaken their immune system.

The common symptoms of viral infections are protruding scales on the body, bulging eyes, itching, curved spine, and red gills. These infections are treatable and can cure them with medicines or by little changes in their routine. 

Overfeeding in fish

Overfeeding is another common cause of fish obesity. If you offer them excessive food, it gradually makes your fish swell.

Overfeeding can lead to constipation more when you give them the wrong diet. You can indicate overfeeding by noticing a few aspects or signs.

Overfeeding also causes other little changes when you give them a high quantity of food, and they produce a large extent of waste.

Uneaten food, algae, smelly odor, and unhealthy fish are signs of overfeeding. If you are unable to sort out the situation, your fish could die eventually. Constipation and overfeeding are dangerous and alarming sign for fish health and life. 

Hexamita in fish

Hexamita is an ailment of fish that cause to produce holes in their head. Hexamita is also known as a hole in the head.

Fish suffering from Hexamita become obese or bloating. It is a dangerous or complicated disease and, it is hard to diagnose because it does not have additional symptoms besides swelling or bloating. In this disease, fish gain weight and look fatty. It is another big reason why they are so fat. 


Constipation may also cause swelling or bloating in your pet fish. Your fish becomes too swollen that they feel difficulty while swimming.

When your fish get constipated, they produce little waste and sometimes no waste. When the stool, their waste are trailing and hard.

Constipated pet fish stop eating. Infections, overfeeding, incorrect diet, and faulty water conditions are the common causes of constipation. If constipation is left unchecked and their condition does not allow improvement, it leads to death. 

Poor maintenance of the fish tank

Bloating or swelling is sometimes caused by improper maintenance of fish. Every fish becomes fatty when they live in unsatisfactory tank condition, wrong diet, and dirty water.

If your aquarium atmosphere is gloomy, it is occupied with dead plants, leftovers, and waste, then inflating should not wonder you.

The dirty or unclean setting and do not change tank water weekly; it could damage or destroy their digestive system and cause constipation for a long time.

You should give them fresh food and should change 25% of tank water per week. You must clean the tank, remove uneaten food, and waste regularly. Keep an eye on the diet fish and notice the difference in their physical appearance and behavior. If you find any change, do not ignore it. 


Tumors are another enormous reason for fish swelling. Enlargement in the fish size can link to tumors. Tumors are mostly, misshaped uneven, and benign. If these tumors are cancerous, there is a very slight chance to treat, and fish survive.

When your fish have tumors, they are not bigger entirely but have a swollen body from one side. All tumors are not always cancer but, a few of them are cancerous.

Your fish need extra care and attention when they have tumors. If they are living in a community tank, you should separate them from other fish. Because some tumors can spread and, some fish tankmates are aggressive.

They can increase their pain and can attack the sick fish. In every disease, you have to clean the tank properly, give them fresh or clean food pallets and water. 

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