How Many Algae Eaters Do You Need for a 20-Gallon Tank? An Essential Guide

Aquarium enthusiasts know that algae can be a real headache. It can turn a beautiful tank into an eyesore and sometimes even pose a risk to the health of the fish. Algae-eating creatures can help you maintain the cleanliness of your tank (without breaking a sweat!). Today, we’ll take a deep dive into a diverse assortment of algae eaters and find the perfect match for your tank.

Isn’t it amazing how little green algae can bring life to your tank and simultaneously wreak havoc? But fear not – introducing a few dedicated algae eaters into your ecosystem is the perfect natural solution. So buckle up, and let’s explore the best algae eaters for your tank!

Before we dive into the exciting world of algae eaters, we must identify the ideal balance of species for your tank. With guidance from experienced aquarists, you’ll know exactly how many nibblers are needed for a 20-gallon tank.

Selection of Algae Eaters

Algae eaters, as the name suggests, are aquatic creatures that feed on algae, and having a few in your tank can be a game-changer. Here’s a list of some popular algae eaters:

Fish Species

  1. Otocinclus Catfish
  2. Siamese Algae Eater
  3. Bristlenose Pleco
  4. Chinese Algae Eater
  5. Molly fish


  1. Nerite Snails
  2. Mystery Snails
  3. Apple Snails


  1. Amano Shrimp
  2. Cherry Shrimp
  3. Ghost Shrimp


  1. Hermit Crabs
  2. Pom Pom Crab
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Factors to Consider

Several factors influence the number of algae eaters that should be added to a 20-gallon aquarium. Some of these factors include:

  1. Size of Algae Eaters
  2. Tank Mates
  3. Algae Growth
  4. Algae Eater Temperament
  5. Aquatic Plants
  6. Water Conditions
  7. Tank Maintenance

Size of Algae Eaters

Each algae eater species has its preferred tank size. For instance, Otocinclus Catfish and Nerite Snails are perfect for smaller aquariums, while Bristlenose Plecos and Chinese Algae Eaters prefer more spacious environments. When deciding on the number of algae eaters for your tank, consider their adult size and the space they need to thrive.

Tank Mates

It’s crucial to ensure the algae eaters are compatible with their tank mates. Some algae eaters like Siamese Algae Eaters and Chinese Algae Eaters can be territorial and aggressive towards their fellow fish. Always check the compatibility between species before adding algae eaters to your tank.

Algae Growth

When determining the number of algae eaters needed, consider the level of algae growth in your tank. Your tank may require just a few algae eaters if algae growth is minimal. More algae eaters should be added if your tank is experiencing rampant algae growth.

Algae Eater Temperament

Some algae eaters, like Otocinclus Catfish and Amano Shrimp, are docile and can live peacefully with various species. Others, like Chinese Algae Eaters, become aggressive as they age. It’s crucial to research the temperaments of the algae eaters before adding them to your tank.

Aquatic Plants

Plants and algae eaters can coexist in your aquarium, but it’s essential to consider the potential damage that some algae eaters might cause. Hungry fish can damage or uproot plants during their algae-noshing missions. Choose algae eaters that won’t damage your precious plants.

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Water Conditions

Ensure that your algae eaters thrive in the same water conditions as the rest of your tank inhabitants. Some prefer harder water, while others live best in soft water. Be mindful of their water temperature and pH preferences before adding algae eaters to your tank.

Tank Maintenance

A well-maintained tank can reduce algae problems, lessening the need for many algae eaters. Regular cleaning, balanced nutrient levels, and appropriate lighting can control algae growth and lead to a healthier aquarium.

Optimal Number of Algae Eaters

After considering all the factors above, the ideal number of algae eaters in a 20-gallon tank would be:

  • 2-4 small fish (like Otocinclus Catfish or Molly fish)
  • 4-6 small snails (such as Nerite Snails)
  • 5-10 shrimp (e.g., Amano Shrimp)
  • 1-2 small crabs

These recommendations ensure that there will be enough algae eaters to keep the tank clean without overcrowding or causing compatibility issues. Remember, sometimes less is more, and providing an appropriate number of algae eaters will help maintain a balanced and healthy tank.


  1. What type of algae eaters are best for beginners?
    • Nerite Snails, Amano Shrimp, and Otocinclus Catfish are suitable algae eaters for beginners because they are easy to care for and adaptable to various tank conditions.
  2. Do algae eaters require supplemental food?
    • Some species, like Bristlenose Plecos, require supplementary food in the form of algae wafers. It’s essential to tailor their diet to their specific needs.
  3. Can all algae eaters coexist in the same tank?
    • While many algae eaters can live together, it’s crucial to research each species’ temperament and compatibility with other tank inhabitants before adding them to your aquarium.
  4. How many algae eaters should be in a 10-gallon tank?
    • It’s recommended that a 10-gallon tank have 1-2 small fish algae eaters, 2-3 snails, or 3-5 shrimp. However, always consider factors like compatibility and tank conditions before deciding.
  5. Do algae eaters eat all types of algae?
    • No, different species prefer different types of algae. For example, Siamese Algae Eaters are known for eating black beard algae, while Nerite Snails prefer green algae.
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With the right balance of algae eaters and a well-maintained tank, you can enjoy a beautiful, healthy aquarium that’s free of those pesky green monsters. So don’t wait! Start exploring the exciting world of algae eaters and give your beloved fish the pristine home they deserve. Good luck, and happy tank-keeping!

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