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Why Is My Pleco Fat And Bloated? (Reasons & Solutions)

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It’s not unusual to observe shifts in the appearance of aquarium fish. For instance, I once noticed that my Pleco fish appeared a little fuller and more bloated than usual.

At first, I couldn’t pinpoint the exact reason for this alteration, but as the days passed, I began to understand the situation better.

What leads to bloating in Pleco fish? How should you address it? Is it a cause for concern? Do Pleco fish gain weight when they have eggs?

In this article, I’ll delve into all these issues, ensuring you leave with all the information you need. Let’s get started.

Why Does My Pleco Look Fat?

There are several causes behind a fat Pleco, including:

1. Overfeeding

Consistently giving plecos more food than they can consume not only makes them appear bulkier but can also have adverse health implications.

  • High Nutrient Intake: Plecos, naturally feeding on detritus and algae, get an unnecessary fat buildup when given too much commercial food.
  • Less Movement: Overfed plecos tend to become notably lethargic, which reduces their energy usage and contributes to their weight gain.
  • Waste Production: Excessive feeding translates into increased waste, which can lead to degraded water quality, impacting the pleco’s health.

2. Constipation

Plecos, like other fish, can suffer from constipation, and when this happens, it results in a noticeably bloated appearance.

  • Pellet Foods: When plecos rely heavily on pellet foods without sufficient greens, they are prone to suffer from constipation.
  • Less Frequent Feces: A constipated pleco will eliminate waste less often, and this accumulated waste gives them a bloated look.
  • Inactivity: Constipation in plecos often results in a noticeable decrease in activity; they might spend more time hiding or just resting.

Also Read: Pleco Fish Swim Bladder Disorder

3. Internal Parasites

Parasitic infections in plecos can cause them to look swollen and bloated, signaling potential health concerns.

  • Unnatural Bloat: Plecos with internal parasites can develop a sudden, uneven bulge, distinctly different from regular growth.
  • Weight Loss: Even if they appear bloated, plecos suffering from parasites might experience weight loss in other body areas.
  • Behavioral Change: Parasitic infections can lead to noticeable behavioral changes in plecos, such as lethargy or scraping against objects in the tank.

4. Egg Bearing in Female Plecos

When female plecos are gravid and carrying eggs, they can exhibit a distinct bloated appearance.

  • Seasonal Changes: During the breeding season, gravid female plecos can visibly swell up as they carry eggs.
  • Specific Bulge Location: The bloat in egg-bearing plecos is typically more prominent in specific body regions, indicating egg presence.
  • Behavioral Indicators: Gravid plecos might become more territorial or seek sheltered spots in anticipation of laying eggs.

5. Dropsy (Fluid Retention)

Dropsy is a condition where plecos retain fluid, causing them to bloat and scales to protrude.

  • Protruding Scales: Plecos with dropsy will have scales that stick out, giving them a “pinecone” appearance.
  • Abdominal Swelling: The most noticeable sign is the swollen abdomen due to fluid accumulation.
  • Behavioral Change: Affected plecos often become lethargic, might lose their appetite, and might hover at the tank’s bottom.

How Do You Treat a Bloated Pleco?

Taking care of a swollen Pleco depends on the root cause. Here’s what you should do:

1. Treating Overfeeding

Overfeeding is a frequent issue with plecos, and rectifying their diet and feeding regimen can help address the bloating.

  • Monitor Food Intake: Measure food portions (e.g., 1-2 pellets per pleco) and remove leftovers after 20 minutes to prevent overeating.
  • Scheduled Feedings: Feed plecos at specific times, e.g., 8 am and 6 pm, ensuring they have a consistent and limited intake.
  • Quality Over Quantity: Choose premium foods (e.g., algae wafers) that offer a balanced nutrient profile, reducing fillers and excess fats. I personally use these Invert Aquatics Mini Algae Discs (link to Amazon).
  • Fasting Period: Once a week, skip feeding for a day, allowing the pleco’s digestive system to process any excess food.

2. Addressing Constipation

Constipation can lead to bloating in plecos. Adjusting their diet and ensuring they get enough fiber can alleviate this issue.

  • Introduce Greens: Offer blanched veggies like zucchini or spinach twice a week, providing necessary fiber for digestion.
  • Decrease Pellet Intake: Reduce the number of pellets, opting for 1-2 pellets less than usual, promoting a more varied diet.
  • Epsom Salt Bath: A brief bath in a solution with 1-2 teaspoons of Epsom salt (link to Amazon) per gallon can help alleviate constipation in plecos.
  • Encourage Movement: Adding new hiding spots or rearranging decor can stimulate plecos to move more, aiding digestion.

3. Eliminating Internal Parasites

Parasitic infections in plecos can cause bloating. Proper diagnosis and treatment can help eliminate these pests.

  • Observe Behavior: Watch for unusual behaviors, such as scratching against objects, which can hint at a parasitic presence.
  • Anti-Parasitic Treatment: Consult a vet for specific treatments, often dosed at 1 ml per 10 gallons, depending on the medication. My recommendation: Fritz Mardel Coppersafe (link to Amazon).
  • Quarantine New Fish: Always quarantine new arrivals for 2-4 weeks, ensuring they don’t introduce parasites into the main tank.
  • Maintain Cleanliness: Regular water changes (e.g., 25% weekly) and tank cleaning reduce the chance of parasitic outbreaks, safeguarding your pleco’s health.

4. Assisting with Egg Carrying

Gravid, or egg-bearing plecos, may appear bloated. Ensuring their well-being during this period is paramount for the health of the mother and potential offspring.

  • Provide Breeding Caves: Supply your tank with suitable breeding caves, allowing females to lay and protect their eggs comfortably. My recommendation: Jabukosu Aquarium Cave (link to Amazon).
  • Optimize Water Conditions: Maintain water parameters like a pH of around 6.5-7.5 and temperatures between 76-80°F (24-27°C) for ideal breeding conditions.
  • Limit Stress: Reduce sudden light changes and loud noises, ensuring a calm environment for your gravid pleco.
  • Offer Nutritious Diet: Provide a high-quality diet, such as vitamin-enriched pellets or fresh veggies, ensuring she receives all essential nutrients during this crucial phase.

5. Managing Dropsy

Dropsy in plecos results from fluid retention, leading to the protrusion of scales and bloating. It’s vital to address this promptly, as it’s often a symptom of an underlying condition.

  • Isolate the Affected Pleco: Move the sick pleco to a quarantine tank, preventing potential spread of illness and offering a calm environment.
  • Epsom Salt Treatment: Administer a bath using 1-3 teaspoons of Epsom salt per gallon, which can help reduce fluid retention in plecos.
  • Consult a Veterinarian: Dropsy can be a symptom of various diseases, so consulting an aquatic veterinarian can offer targeted treatments.
  • Maintain Water Quality: Regularly check water parameters, ensuring ammonia and nitrites are at zero and nitrates are below 20 ppm, as poor water quality can exacerbate health issues in plecos.

Do Plecos Always Get Fat When Carrying Eggs?

No, not all plecos appear noticeably fatter when carrying eggs. The degree of visible bloating varies significantly between species and individual fish.

  • Species Variation: Different pleco species have varying body structures. For instance, Bristlenose plecos may show more pronounced bloating compared to the slender Zebra pleco.
  • Size of the Clutch: Some plecos lay larger clutches of eggs, which can lead to a more noticeable swelling in their abdominal region.
  • Age and Size: Younger, smaller plecos might not display as pronounced bloating when gravid as compared to their mature, larger counterparts.
  • Tank Observations: Often, aquarists notice other behavioral changes, like increased territoriality, before observing physical changes in egg-carrying plecos.

Is My Pleco Overweight from Carrying Eggs or Is It Sick?

Determining whether your pleco’s bloating is due to carrying eggs or a health issue requires careful observation.

Both conditions present distinct signs, and differentiating between them is crucial for the fish’s well-being.

  • Location of the Swell: Gravid plecos typically have a more pronounced swelling in the lower abdominal area, while illness-caused bloating can appear generalized.
  • Behavioral Changes: Egg-carrying plecos often become territorial, guarding specific spots or caves. In contrast, sick plecos may show lethargy or loss of appetite.
  • Duration of Bloating: If a pleco is gravid, the bloated appearance will eventually lead to egg-laying in days or weeks. Persistent bloating without egg-laying can indicate health issues.
  • Scales Appearance: Dropsy, a disease, causes the scales to protrude, giving the pleco a “pinecone” appearance. Egg-bearing doesn’t affect the scales this way.
  • Tankmates’ Behavior: If other fish in the tank are also exhibiting symptoms or changes in behavior, it might be indicative of a water quality issue or disease affecting multiple inhabitants, not just an egg-bearing pleco.

Also Read: Why Is My Pleco Floating Upside Down?

Pleco fish eggs

Distinguishing Between Male and Female Plecos

Obviously, only female Plecos can gain weight and become bloated due to pregnancy. 

Determining the gender of plecos can be challenging, but there are specific markers to look out for. These differences become more apparent as plecos mature.

  • Bristles on Nose: In many species, like the Bristlenose pleco, mature males develop notable bristles or “tentacles” on their nose, while females have few or none.
  • Body Size: In certain species, females tend to be slightly larger and have a rounder body, especially when viewed from above.
  • Genital Papilla: Located near the anal fin, the genital papilla in females is broader and rounder, while in males, it’s pointier and smaller.
  • Pectoral Fins: Male plecos often have thicker and broader pectoral fins, which they use during territorial disputes.
  • Ventral Region: When observed closely, the ventral area of males is typically flatter, while females have a more rounded or protruded ventral profile, especially during breeding seasons.


For quick readers, here’s a short recap:

  • Plecos can appear bloated due to reasons like overfeeding, constipation, internal parasites, egg-bearing in females, or dropsy (fluid retention).
  • Overfeeding can be rectified by monitoring food intake, scheduling feedings, prioritizing quality foods, and periodic fasting.
  • Addressing constipation in plecos involves introducing greens, decreasing pellet intake, using Epsom salt baths, and stimulating more activity.
  • Parasitic infections require behavior observation, anti-parasitic treatments, quarantining new fish, and maintaining tank cleanliness.
  • Differentiating between egg-bearing and illness in plecos requires observing the location of swelling, behavioral changes, bloating duration, scale appearance, and the behavior of tankmates.