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Why Is My Pleco Coming To The Surface? (5 Easy Solutions)

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When I first brought home my pleco fish, I couldn’t help but notice something strange. It kept swimming to the surface, almost like it was gasping for air.

I did a deep dive into some research, and after a bit of trial and error, I managed to figure out the problem.

In this article, I’ll walk you through what I learned so you can help your fish too. Let’s dive right into it.

Why Is My Pleco Swimming to the Surface?

Here are some possible reasons that might have caused your pleco to swim to the surface:

1. Lack of Oxygen

Plecos, like most fish, rely heavily on the right levels of dissolved oxygen to breathe properly. When the water lacks enough oxygen, plecos can be seen darting or lingering at the surface.

  • Oxygen Saturation: Different temperatures affect water’s oxygen-carrying capacity; when water is warmer, it typically holds less oxygen, compelling plecos to seek oxygen at the surface.
  • Surface Agitation: Tanks that lack adequate water agitation at the surface can experience reduced oxygen levels, which can lead plecos to frequent the surface more.
  • Respiratory Distress: If plecos are spotted gasping or making repeated trips to the surface, it’s a clear sign of their struggle with oxygen levels.

Also Read: Stress In Pleco Fish

2. Searching for Food

Plecos have a natural tendency to scour surfaces, including the substrate and decor, in search of food.

If their dietary needs aren’t met, they might venture to the surface, hoping to find some nourishment there.

  • Natural Behavior: Plecos, in their natural habitat, explore various water levels, including the surface, looking for algae and other food particles, and this behavior can be mirrored in home tanks.
  • Underfeeding: Persistent hunger may drive plecos to extend their search for food to the water’s surface, particularly if they suspect food availability.
  • Observation Patterns: Witnessing plecos near the surface during usual feeding times could suggest their intent to find food there.

3. Gill Issues or Parasites

Gills are essential for plecos’ respiration. However, when afflicted by parasites or other issues, plecos might swim upwards, seeking relief or more oxygen.

  • Gill Flukes: This common parasitic issue can interfere with the ability of plecos to extract necessary oxygen from water, pushing them towards the surface.
  • Red or Swollen Gills: An indication of potential gill issues, afflicted plecos might instinctively head to the surface, associating it with better oxygen access.
  • Behavioral Changes: Constant observation can reveal if plecos display unusual behaviors, such as scratching against objects, hinting at gill issues.

4. Poor Water Quality

Toxins or chemical imbalances in water can greatly stress out plecos. Erratic behaviors, including frequent trips to the surface, might be a reaction to deteriorating water conditions.

  • Ammonia and Nitrite Presence: These toxic substances, when present in higher concentrations, can be very distressing for plecos, causing them to seek relief at the surface.
  • Regular Testing Importance: Consistent checks of water parameters can reveal issues, and any anomalies might be causing distress to plecos.
  • Change in Behavior: Any noticeable shift in pleco behavior, such as lethargy or frequent surface visits, might point towards suboptimal water conditions.

5. Reacting to External Stimuli

Plecos are sensitive to their environment. External stimuli, like sudden lights or vibrations, can startle them, causing a rush to the surface.

  • Tank Placement: If a tank is in a high-traffic area or exposed to direct sunlight, plecos might often get startled and swim upwards.
  • Sudden Changes: Plecos are not fans of rapid alterations in their environment; quick temperature shifts or lighting changes might drive them to the surface.
  • Observation: Keeping a keen eye on when the plecos dart to the surface can provide clues if it’s in response to external factors.

What to Do If Your Pleco Is Going to the Top of the Tank?

Here’s how to address the issue if your pleco is frequently going to the top of the tank:

1. Improving Oxygen Levels

Plecos require a stable oxygen-rich environment. If they’re frequently swimming to the surface, it’s indicative of a possible oxygen deficiency.

  • Adequate Filtration: Ensure you have a filter rated for your tank size, e.g., for a 50-gallon tank, aim for a filter rated at least 60-70 gallons to boost oxygen circulation for plecos.
  • Air Stones and Pumps: Add air stones connected to an appropriate-sized air pump; for instance, a 2-watt pump would suit a 20-gallon tank. I personally picked the incredible Hygger Aquarium Air Stone (link to Amazon).
  • Regular Water Changes: Replace 20-25% of the tank water weekly; this helps replenish oxygen and removes potential toxins that can stress plecos.
  • Tank Temperature: Keep water temperature around 76-78°F (24-26°C) for most plecos; cooler water retains more oxygen, benefiting their respiratory needs.

Also Read: Do Plecos Need A Bubbler?

2. Enhancing Food Availability

Plecos might swim to the surface if they’re hungry or searching for more variety in their diet.

  • Varied Diet: Offer plecos a mixture of algae wafers, blanched vegetables (like zucchini or spinach), and sinking pellets to ensure a balanced diet. My recommendation: Invert Aquatics Mini Algae Discs (link to Amazon).
  • Feeding Frequency: Feed plecos 2-3 times a week, but ensure leftover food is removed to prevent water quality deterioration.
  • Automatic Feeders: For consistent feeding when you’re away, consider an automatic feeder set to release pleco-friendly food.
  • Observe Eating Patterns: Watch your plecos during feeding; if they’re not eating, you might need to adjust the food type or quantity.

Also Read: What Do Plecos Eat?

3. Addressing Gill Issues and Parasites

Gill problems can hinder plecos’ breathing, causing them to seek oxygen at the surface.

  • Regular Check-ups: Examine plecos’ gills weekly; reddened or swollen gills can be a sign of infections or parasites.
  • Quarantine New Additions: Before introducing new fish, quarantine them for 2-3 weeks to prevent potential parasite transmission to your plecos.
  • Anti-parasitic Treatment: If parasites are suspected, consider treatments like Coppersafe (link to Amazon); always dose according to the product’s instructions and tank size.
  • Water Quality Maintenance: Ensure ammonia and nitrite levels are at 0 ppm; high levels can exacerbate gill issues in plecos.

Also Read: Pleco Fish Diseases

4. Enhancing Water Quality

Good water quality is essential for pleco health. Poor conditions stress plecos, possibly leading them to seek refuge at the surface.

  • Regular Testing: Use a reliable water test kit weekly to check parameters: aim for ammonia and nitrite at 0 ppm and nitrate below 20 ppm for plecos’ well-being. I personally use the well-known API Freshwater Master Test Kit (link to Amazon).
  • Water Changes: Conduct 20-25% water changes weekly; this removes potential toxins and ensures a fresh environment for your plecos.
  • Natural Filtration: Consider live plants like Java fern or Anubias; they absorb excess nitrates, enhancing water quality for plecos.
  • Filter Maintenance: Clean or replace filter media monthly (or as recommended) to ensure efficient toxin removal and provide a cleaner habitat for plecos.

5. Managing Responses to External Stimuli

Plecos can be sensitive to sudden changes or disturbances in their environment, causing them to swim to the surface.

  • Stable Lighting: Maintain consistent lighting hours, typically 8-10 hours daily; sudden light changes can startle plecos.
  • Tank Placement: Place the tank away from high-traffic areas or loud noises. For example, avoiding placement near doorways can reduce stress for plecos.
  • Tank Cover: Using a tank lid or mesh cover prevents plecos from jumping if startled while also offering a sense of security.
  • Avoid Sudden Movements: When approaching or working in the tank, move slowly; sudden movements can stress and frighten plecos, driving them upwards.

Can Plecos Breathe Air?

No, plecos cannot breathe air like humans or some other aquatic species.

They primarily rely on gills to extract oxygen from water, but they have some ability to intake air under specific circumstances.

  • Gill Breathing: Plecos primarily use their gills to extract oxygen dissolved in the water, which is their main respiratory method.
  • Labyrinth Organ Absence: Unlike some fish, like bettas or gouramis, plecos lack a labyrinth organ that allows air breathing.
  • Surface Oxygen Intake: In low-oxygen environments, plecos might dart to the surface, not to breathe air, but to access water with higher oxygen concentration.
  • Oxygen vs. Air: It’s crucial to differentiate between oxygen dissolved in water and atmospheric air; plecos need the former, while the latter is not how they respire.

Also Read: Why Is My Pleco Breathing Fast?

Can Plecos Jump Out of the Tank?

Yes, plecos can and sometimes do jump out of the tank, especially if they are stressed or feel threatened.

While it’s not a common behavior for all plecos, certain situations or species might be more prone to this action.

  • Species Differences: While all plecos have the potential to jump, species like the Rubber Lip Pleco or Bristlenose Pleco might be more active jumpers under stress.
  • Stress Triggers: Factors such as poor water quality, tank mates’ aggression, or sudden changes can make plecos feel threatened and jump.
  • Tank Lids: To prevent any unfortunate escapes, always ensure your tank has a securely fitted lid or mesh cover.
  • Water Parameters: Maintaining stable conditions, such as a temperature around 76-78°F (24-26°C) for most plecos, can reduce stress-related jumping.
  • Observation and Behavior: If you notice erratic behavior or frequent surface visits, it’s a sign to check your tank conditions and ensure pleco well-being.


For quick readers, here’s a short recap:

  • Plecos swim to the surface due to reasons like lack of oxygen, inadequate food supply, gill issues or parasites, poor water quality, or reactions to external stimuli.
  • To address plecos frequenting the surface, focus on improving oxygen levels, enhancing food availability, treating gill problems, maintaining optimal water quality, and managing their response to external changes.
  • Contrary to some beliefs, plecos cannot breathe air like humans; they primarily use gills for oxygen extraction from water and might access surface water in low-oxygen conditions.
  • Plecos have the potential to jump out of the tank, especially under stress; ensuring tank lids and maintaining stable water conditions can prevent this behavior.
  • For plecos’ health, consistent water testing, regular tank maintenance, and keen observation of their behavior are essential.