Fertilized vs. Unfertilized Pleco Eggs: A Complete Guide

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Plecos are pretty exciting fish, but breeding them can be a bit confusing. People often have a lot of questions about their eggs.

How do you know if Pleco eggs are fertilized or not? What should you do with each kind? And how long does it take for the fertilized eggs to hatch?

In this guide, I’ll answer all these questions and more, so you leave with all the information you need. Let’s get started.

Also Read: Pleco Fish Eggs

FeatureFertilized Pleco EggsUnfertilized Pleco Eggs
ColorVibrant amber or orange shadePale or gray hue
OpacityIncrease in opacity indicating growthNo increase in opacity, remain transparent
Dark SpotVisible and enlarging dark spot inside the eggAbsence of a forming dark spot
Shape and IntegritySolid, intact appearance without deflation or dentingMay appear deflated or have an irregular shape
AttachmentFirmly attach to surfaces like tank walls or decorationsWeak or no attachment to surfaces
Size ConsistencyUniform size, generally around 2-3mmSize may vary, and consistency is not guaranteed
Time Frame for ChangesChanges noticeable within 7-10 days post-fertilizationNo significant changes observed over time

Signs of Fertilized Pleco Eggs

Fertilized Pleco eggs typically manifest a wholesome, amber or orange hue and steadily transition to an opaque state as the embryos advance.

A distinct, enlarging dark spot within the egg confirms the healthy development of Pleco fry.

  • Coloration: Fertilized Pleco eggs consistently show a vibrant amber or orange shade. This color, observed under a soft light, signals a healthy, progressing embryo.
  • Opacity Increase: The egg’s increasing opacity, noticeable after a few days, underlines the growth within. This change from a translucent state is a positive indication of a developing Pleco embryo.
  • Dark Spot: A visible and enlarging dark spot inside each egg is a conspicuous sign. It represents the Pleco fry’s growth, foretelling a successful hatching in the coming days.
  • Egg Integrity: Fertilized eggs demonstrate a solid, intact appearance. For instance, they do not show any signs of deflation or denting, maintaining a robust form indicative of healthy Pleco development.
  • Attachment: Healthy Pleco eggs firmly attach to surfaces, such as tank walls or decorations. This adhesion showcases their vitality and increased chances of yielding healthy Pleco fry.
  • Size Consistency: The uniformity in size among fertilized Pleco eggs, generally around 2-3mm, further confirms their health. A consistent size throughout the clutch signals proper and synchronous development.
  • Time Frame: Usually within 7-10 days post-fertilization, noticeable changes signify healthy progression. These signs, observed closely, ensure the expected arrival of new Pleco fry.

Signs of Unfertilized Pleco Eggs

Unfertilized Pleco eggs, conversely, display a distinct pale or grayish color and may appear deflated or irregular in shape.

They do not exhibit the gradual opacity or dark spots characteristic of fertilized eggs.

  • Pale Color: Unfertilized Pleco eggs manifest a noticeable pale or gray hue. This coloration, unlike the vibrant amber of fertilized eggs, often indicates a lack of embryo development within.
  • Lack of Opacity: Absence of increasing opacity in these eggs highlights the absence of growth. The sustained transparency signals a stagnant, non-developing state for the Pleco eggs.
  • No Dark Spot: The absence of a forming dark spot within the egg is a clear indicator. Without this sign, the expected Pleco fry development is unfortunately unlikely.
  • Deflation or Irregular Shape: Unfertilized eggs may appear deflated or possess an irregular form. Such physical attributes indicate the lack of a developing Pleco embryo inside.
  • Weak Attachment: These eggs might display weak or no attachment to surfaces, further confirming their unfertilized state. This characteristic, alongside others, signals a low likelihood for successful Pleco development.

Also Read: What Do Pleco Fish Eggs Look Like?

What Should You Do with Fertile Pleco Fish Eggs?

For fertile Pleco fish eggs, promptly and carefully transfer them to a separate, secure aquarium setting where they can develop undisturbed.

Ensure this dedicated space has optimum water conditions and is free from potential predators to enhance the eggs’ survival chances.

  • Secure Environment: Set up a 10-gallon tank for the Pleco eggs, keeping it isolated from other fish to prevent predation and ensure a peaceful environment.
  • Optimal Water Conditions: Keep water at 28°C (82°F) and pH 6.5-7.5, to mimic natural Pleco habitat, encouraging healthy development.
  • Gentle Water Flow: Install a low-flow filter to imitate a natural current, helping supply oxygen to the Pleco eggs efficiently.
  • Proper Oxygenation: Place an air stone in the tank. This ensures a steady supply of oxygen which is crucial for the successful hatching of Pleco eggs. My recommendation: Hygger Aquarium Air Stone (link to Amazon).
  • Regular Monitoring: Check the tank daily, observe the state of the eggs, and make the necessary adjustments to promote the healthy growth of developing Plecos.

What Should You Do with Unfertilized Eggs?

Upon discovering any unfertilized Pleco eggs, promptly remove them from the tank.

This action halts decay, protecting the water quality and other fish. Properly discard these eggs to keep the remaining Plecos and their habitat in good condition.

  • Quick Removal: Promptly take out unfertilized Pleco eggs with a gentle, fine net, maintaining water cleanliness and protecting the other eggs.
  • Safe Disposal: Safely dispose of the eggs in a waste bin, avoiding any tank contamination and ensuring ongoing Pleco well-being.
  • Clean the Tank: After removal, cleanse the specific tank area to eliminate any lingering matter, assuring a secure environment for the Plecos.
  • Monitor the Other Eggs: Continue watching the other eggs to ward off additional problems and uphold a healthy setting for both developing and adult Plecos.

How Long Does It Take for Fertilized Eggs to Hatch?

Fertilized Pleco eggs generally hatch within 7 to 10 days post-fertilization, although this timeline can shift based on water conditions and specific Pleco species.

  • Water Temperature: Hold the water temperature at approximately 28°C (82°F) for ideal Pleco egg conditions, aiding a punctual hatching period.
  • Regular Checks: Consistently monitor the Pleco eggs daily to note any alterations and confirm the environment remains stable for hatching.
  • Species Differences: Note that different Pleco species may exhibit varied hatching times, necessitating tailored care and attention.
  • Minimize Disturbances: Ensure the area around the Pleco eggs is calm and undisturbed, fostering a healthy and on-time hatching process.
  • Ensure Adequate Oxygen: Guarantee adequate oxygen levels using air stones, backing the healthy growth and successful hatching of Pleco eggs.

Also Read: Pleco Fish Eggs Hatching Time

Why Aren’t My Pleco Fish Eggs Hatching?

If Pleco eggs are not hatching, several factors like inappropriate water conditions, insufficient oxygen, or potential fungus growth could be responsible.

Thoroughly assess and rectify these issues for successful Pleco egg hatching.

  • Inappropriate Water Conditions: Keep the water at 28°C (82°F) and pH 6.5-7.5 as unfavorable conditions can prevent Pleco eggs from hatching.
  • Lack of Oxygen: Employ an air stone to assure ample oxygen, a lack of which can hinder Pleco egg development and hatching.
  • Possible Fungal Infection: If eggs turn white, a fungal problem may be present. Extract these eggs and treat the water to protect the remaining Pleco eggs.
  • External Disturbances: Maintain a tranquil and stable tank environment. Excessive motion or alterations can stress Plecos and disrupt egg hatching.
  • Unfertilized Eggs: Remove any unfertilized eggs swiftly to avoid decay and maintain water quality for other Pleco eggs.

What to Do After Fertilized Eggs of Pleco Hatch?

After hatching, transfer the Pleco fry to a rearing tank with appropriate water conditions and provide nutritious food.

A safe and nutrient-filled environment will bolster the healthy growth and development of Pleco fry.

  • Rearing Tank: Transfer Pleco fry to a 10-gallon rearing tank, providing enough space and security for growth.
  • Proper Nutrition: Offer Pleco fry high-grade, size-appropriate food to boost their health and development.
  • Adjusted Water Conditions: Keep water temperature at 25°C-28°C (77°F-82°F) and pH 6.5-7.5 for optimal Pleco fry growth.
  • Regular Monitoring: Continuously monitor Pleco fry to tackle any issues immediately and ensure their well-being and development.
  • Gentle Filtration: Employ sponge filters in the rearing tank to maintain clean water without risking delicate Pleco fry with harsh water currents.


For those short on time, here’s a quick wrap-up:

  • Vibrant colors, opacity, dark spots, integrity, and attachment characterize fertilized Pleco eggs for healthy development.
  • Unfertilized Pleco eggs show pale color, lack of opacity, absence of dark spots, irregular shape, and weak attachment.
  • Fertile Pleco fish eggs need a secure environment, optimal water conditions, gentle water flow, sufficient oxygenation, and regular monitoring.
  • Prompt removal, proper disposal, and tank cleaning are essential for unfertilized Pleco eggs for the health of remaining eggs.
  • Fertilized Pleco eggs generally hatch in 7-10 days with attentive temperature maintenance, monitoring, species-specific knowledge, and sufficient oxygenation.