Since male guppies do not become pregnant, a sudden swollen or bloated belly should be diagnosed. However, it’s okay for females to become bigger with bulged bellies when pregnant. Therefore, observing their physical appearance and behaviors is important to know when they are sick, pregnant, or overfed.
Guppy dropsy is one of the main causes of swollen bellies in fish. It results from fluid or water imbalance in the visceral cavity. A guppy can become rounder with a big belly due to overfeeding, bloating, constipation, dropsy, or infections. This makes them less active and dull.
Swollen body tissues in a guppy can make it look more round. This is often caused by liquid and gas build-up in their cavities. The belly is the major part of a fish that is often affected when a guppy experiences fluid imbalance.
| Symptom | Cause |
| Abnormally swollen belly | Dropsy |
| Sudden big belly after eating | Overfeeding |
| Irregular swelling like a lump | Tumour |
| An evenly swollen belly that disappears after sometime | Bloating |
| Overall increased weight and fatness | Obesity |
| A sudden increase in weight and lethargy | Infection |
Causes of guppy big belly (dropsy)
Dropsy is a condition commonly identified by abnormal swelling on a fish’s belly. It is one of the most likely reasons that may cause a male guppy to have a swollen belly.
Guppies suffering from dropsy accumulate water and gas in their cavities. This happens internally and causes an outward bulge since the fluids and gasses are trapped in the skin and internal organs. In severe cases, the fish/guppy will have a ballooned appearance, with its belly looking like it is about to burst.
The condition results from various factors, including infections, bloating, injuries, and gas build in body tissues. If there is an infection, bacteria and other microorganisms produce gases when performing their normal digestive activities. The produced gases fill the body cavities in the process.
1. Overfeeding
Overfed guppies have swollen bellies that may make them appear bigger than usual. The condition may be worse if the guppy is constipated. A constipated guppy will experience gas build-up in the body.
In the same way, as in dropsy, gases generated due to constipation in the fish rush to fill all the body’s cavities. Since constipation occurs within the digestive tract, the stomach is the biggest space the gases will rush to fill.
2. Weight gain
It is normal for guppies to gain weight, especially if their feeding is not regulated. If the protruding bellies appear after a long breeding period, there is no need to worry as it may be a normal weight gain. However, there might be enough reasons to worry if it happens abruptly and is abnormally big.
3. Tumors
Tumors refer to growths that may appear anywhere within a guppy’s body. The belly is one area that is prone to tumors and growth. If a guppy develops tumors in the belly, it will have a protruding area as the swollen masses require more space.
4. Infections
Bacteria, parasites, and viruses are responsible for swollen fish bellies. These microorganisms undergo natural processes that often require a gaseous exchange. The gases they produce often rush out in an attempt to find their way out.
In that regard, they will first fill all the available spaces before they can leave the body. The condition is most likely to cause a swollen belly in a male guppy, especially if the infection is in the belly.
5. Poor water conditions
Certain water conditions may not favor guppy rearing. Guppies prefer water with a pH of 6.8 to 7.8. Imbalanced pH may result in the water being drawn into the fish through osmosis. This leads to excessive fluid -within the guppy’s cavities which will cause swelling.
When to worry
A sudden swollen or bulging belly should be checked, especially when accompanied by lethargy. Usually, a usually active guppy becomes less aggressive, significantly changing its usual movement patterns.
However, overfeeding should not be a major cause of concern. This can be noted when they have an extra large belly after eating. This should disappear after some time due to digestion. However, managing and controlling when and what they eat in a tank is very important.
Critical conditions like swollen bellies from infections and diseases should be alarming. It is okay to worry because treating certain infections in fish is never easy. Continuous cases can confuse when identifying a male guppy with a big belly from a pregnant guppy that is not giving birth.
How to know if a guppy is fat
A fat guppy is a jolly guppy! It is fun to know that your guppy is simply fat and not pumped up due to underlying infections or conditions. Fat guppies will maintain their usual activity levels and show no signs of stress like extra lethargy.
Their bodies will not appear like they are about to burst due to the swelling. Fat guppies also maintain favorable feeding habits. They may eat more than before due to their increased body size.
It’s a fact that when a guppy is fat, it increases its overall size and not just the belly. They will maintain those changes for a period of time. They will not lose weight abruptly unless there are stressful conditions within the environment.
This video will help in clarifying between a giant and a normal-sized male guppy:
How to help a guppy with a big bloated belly
It is okay for a male guppy to grow big but not to be extra bulged. Therefore, it is good to know what is okay and what’s not before taking any measures.
Avoid “meaty” foods such as bloodworms and tubifex worms as they may contribute to Malawi bloat, a fatal condition similar to dropsy where the fish inflates and looks like a pinecone.
Massachusetts Institute of Technology
Here are a few options on how to help a male guppy with a big belly:
1. Osmotic pressure treatment
Osmosis is a great way to reduce fluid imbalances in the fish’s body cavity. To raise the concentration, there is a need to add a teaspoon of salt for each gallon of water in the tank. The water in the guppies’ bodies will move from areas of lower concentration (in the fishes’ bodies) to areas of higher concentration.
Salty water draws fresh water from the guppies’ bodies, helping reduce the fluid build-up in the guppies. However, this can stress any species that is used to fresh water. So do not opt for this solution without consulting a professional.
2. Laxative treatment
Guppies may need laxatives to reduce the gases built up in their bellies. The most common laxative for guppies is tinned peas.
Peas should be administered according to the guppies’ sizes. For instance, bigger guppies can be fed with whole peas, while younger ones may require that the pea grains are broken into smaller pieces.
3. Maintaining good water quality
The first and most basic way to treat fish health conditions is usually to maintain good water quality. Good water does not allow harmful bacteria to survive. Hence, it reduces the chances of infections and, by extension, prevents unwanted bloating.
Keeping guppies is fun! Great guppy keepers know how to differentiate between male and female guppies. That way, it is easier to tell if a female guppy is pregnant and not confuse it for a male with a big belly.
Satisfaction comes in seeing guppies growing fat or more rounded. The case might raise questions if it were more rampant in male guppies alone. One may be perplexed because if the guppies were kept in the same conditions in a single tank, they are supposed to grow uniformly.
