Otocinclus Vs. Pleco: Which One is Better?

In the aquarium hobby, algae growth is a major issue, and most aquarists want to control this problem by introducing algae-eating catfishes like Otocincluses and Plecos to their aquariums. 

Otocincluses are better than plecos not only as algae eaters but also in every other expects. Common Plecos eat plants, grow big, and have high bioload, whereas, Otocincluses don’t. However, Otocinclus don’t do well when kept alone. But a single pleco will live alone and work as a single cleaning crew happily.

Here are 10 points to consider before deciding to go with Otocinclus or Pleco:

  • Size Comparison
  • Minimum School Size
  • Minimum Tank Size
  • Cost
  • Water Parameters
  • Temperament
  • Ideal Tank Mates
  • Diet or Food Preference
  • Care Difficulty
  • Ease of Breading

Ahead, we will go through each of these points above so you can determine with certainty whether a pleco or otocinclus is the better choice for your aquarium. Make sure you keep reading the whole thing, as the article is going to be packed with valuable information!

Otocinclus or Pleco? Before You choose, Consider These 10 Points:

Size Comparison:

Otos are very small in size in comparison to plecos. Depending on the species, otos grow from 1 to 2 inches. 

The largest species of otocinclus (O. flexilis) grows around 2.1 – 2.2 inches in the wild. In captivity, most otocinclus grow about 1.5 inches on average.

On the other hand, I have seen Plecos which are bigger than my hands. Of course, those were wild ones.

Depending on the species, plecos usually grow from 6 – 8 inches in an aquarium. However, there are several dwarf species of plecos, such as Candy Striped Pleco, Bristlenose pleco, and Clown plecos which can grow only up to 4 inches.

This is the most interesting thing about plecos. They are available in various species & every species are different in nature, size, and tank requirements.

Recommended Article: Do Plecos Grow To The Size of The Tank?


In terms of size comparison, I think smaller fishes are easier to keep as most beginner aquarists usually have smaller aquariums. Also, smaller fish will have a small bioload, so in this category, Otocinclus will stay ahead.

Minimum School Size:

Otocinclus catfishes do well when kept in schools of at least 4-5. The more is their number the more secure they will fill.

If you keep a school fish like otocinclus alone or in a smaller school, they are most likely going to be shy and will stay hidden behind rocks or plants in the aquarium all the time.

Trust me, it’s not a good idea to keep a single schooling fish in your aquarium. I have made this mistake in the past. That’s why I highly forbid everyone to make the same mistake. Keep at least 5 Otos together in a 20-gallon tank, and they will be very comfortable.

Now, when it comes to plecos, they are not schooling fish. Most fish keepers keep only one or two plecos in their tank, and plecos do just fine.

So, the minimum otocinclus to keep is at least 5. But you can keep a single pleco without any problem.

Minimum Tank Size:

Yes, you can keep 4-5 otocinclus in a 10-gallon species-only tank and they will do just fine. But most aquarists will keep otocinclus in a community tank.

So, the ideal tank size for a school of otocinclus would be 20 gallons. You can add 5-6 Otos in a 20-gallon tank along with a few neon tetras or any other peaceful community fishes; it’s as simple as that.

Now, let’s make things really complicated. I have seen over 10-15 species of plecos, and they vary a lot in size.

If you are getting a common pleco, it’s most likely going to be over 8 inches. So, at least a 50 – 60 gallon tank is highly recommended for the common pleco.

But if you get a single dwarf species of pleco, then a 20-gallon tank is the bare minimum. 


Otocinclus are available in most pet stores across the USA. They cost around 50 to 60 cents each.

But you have to buy at least 4 of them. I have seen some pet store owners won’t sell single otocinclus.

One of my friends bought 6 Otocinclus recently for only 3.5 bucks. On the other hand, each pleco will cost you from $4 – $6 dollars depending on the size and species.

So, even if you buy a school of Otos, it’s always cheaper.

Water Parameters:


The Ideal temperature to keep Otocinclus catfish is around 72-80 Degrees Fahrenheit. Otocinclus prefer water to be slightly acidic. The ideal pH range for Otocincluses is around 6.0 to 7.5.

They will survive even if the pH is slightly higher but you need to make sure the Nitrites and Nitrates are at 0 PPM. This means the water needs to be cycled. It’s better if you introduce otocinclus in an already established tank.

Irin from Girls talk fish keeps her Otos at 8 to 8.2 pH and she says they are doing just fine.

Suitable Water Parameters For Otocinclus:

pH6.0 to 7.5.
Temperature72-80 ° F
Nitrites0 PPM
Nitrates0 PPM


Now, Plecos can live in a wide range of temperatures and pH levels as they are super hardy. But if you ask me what the ideal temperature for Plecos is, I would say around 75 – 80° F.

I had 3 Plecos in the past, and I kept them in higher temperatures like 82-83 degrees, and I didn’t see any problems with them.

As most aquarium hobbyists suggest, the ideal pH range for most species of Plecos is between 7 to 8.

Suitable Water Parameters For Plecos:

pH7 to 8.
Temperature75 – 80° F.
Nitrites0 PPM
Nitrates0 PPM

Check out my recommended water parameter testing kit on Amazon to help you determine if your tank is suitable for either of these fishes.


Smaller Plecos are shy and peaceful in nature. They love to socialize with other fish and don’t bother or attack anyone.

But when plecos grow large, I have seen some aggression and territorial behavior in them.

A full-grown common pleco can be a little aggressive. So, I don’t recommend anyone to get a common pleco.

However, dwarf plecos like Bristlenose or clown plecos usually are peaceful and non-aggressive.

On the other hand, Otocinclus are one of the most peaceful fish in the aquarium hobby. They never bother other fishes or their own kind.

You can keep them with any other peaceful fish of similar size in a community tank without any issue.

When we talk about plecos, it a quite broad topic as there are different types of plecos. To know about the behavior of bristlenose pleco, check out our article on, Are Bristlenose Plecos Aggressive?

Ideal Tank Mates:

Ideal Tank Mates For Otocinclus:

  • Guppies
  • Mollies
  • Tetras
  • Rasboras
  • Shrimps
  • Kuhli Loaches
  • Dwarf Plecos

Ideal Tankmates For Plecos:

  • Livebearers
  • Corydoras
  • Bettas
  • Otocinclus
  • Honey Gourami
  • Neon Tetras

Recommended articles:

Diet or Food Preference:

Both Otocinclus and pleco love to eat algae that grow on the surfaces of the aquarium. You can also feed them algae wafers and vegetables like zucchini.

Otocinclus are pickier about foods, while Plecos are opportunistic eaters and will eat anything they find edible.

Even some species of plecos eat natural plants in the planted aquarium. Although both Oto and Pleco are omnivorous, their diet should contain mostly plant-based food and be low on meat-based food.

Some people think that Plecos eat fish poop. I have written a complete article on this. Check it out by clicking here.

Related Article: Can Pleco Eat Cucumber?

Care Difficulty:

Plecos are easier to take care of especially if you are a beginner in this hobby. They are forgiving. They will eat anything you provide them.

But otocinclus are quite the opposite. You have to make sure the temperature doesn’t fluctuate too much, and the level of ammonia is zero.

On the other hand, plecos are too hardy. They can tolerate fluctuations in temperature, pH, and as well as a certain level of ammonia in the water.

Ease of Breading:

Plecos are easier to breed. To breed them successfully, it’s better to keep the breeding pair in a separate tank and give them hiding places and caves for some privacy, and you will be seeing little pleco babies in no time.

Female plecos usually lay eggs in the eggs, and male plecos guard their eggs until all the eggs are hatched into little fires.

Now, let’s talk about breeding Otocinclus. Breeding otos is not an easy task. Otocinclus usually do not breed in captivity.

I did some research on these fishes, and you will be surprised to know that all the otocinclus you find in the pet stores are wild-caught.

This is because otocinclus don’t usually breed in tanks. However, very few expert aquarium hobbyists claim that they have bred otocinclus. I have found a video of Master Breeder Dean.

He explains how you can breed otocinclus but trust me, not an easy task, and you don’t want that many complications. If you want easy breeding, just get some livebearers.

As a side note, some species of plecos breed like crazy. Check out my article on, How Often Do Plecos Breed? You may find this article helpful.

So, Which One Is the Best Algae Eater?

If you have already read this far, I think you might know the answer by now. Of course, Otocinclus is far better as an algae eater than a pleco.

Algae outbreak is a very common problem in a planted tank. As many pleco species are well known to eat plants, I don’t recommend plecos in a planted aquarium.

For all these reasons, I think Otocinclus is the better Algae eating Nano fish than plecos, especially for planted aquariums.

Other Things To Know About Otos & Plecos:

Can Plecos Live with Otocinclus?

Yes, plecos can live with otocinclus. You can keep small or dwarf species of plecos with otocinclus without any issue. But don’t keep giant plecos with Otocinclus as they are certainly going to end up as food.

Are Otocinclus For Beginners?

Otocinclus are not suitable for beginners. Most beginners usually make a lot of mistakes when they try to keep otos and end up killing them.

If you are a beginner and you want oto catfish, do enough research yourself and learn about the needs of these fishes, then go for it.

Are Otocinclus Good Algae Eaters?

Yes, Otocinclus are very good algae eaters. They love eating algae that grow on the surfaces of the fish tank, stone, and plants.

Are OTOS Plecos?

Otos and plecos are not the kind same fish. Although both are catfish and have sucker mouths, they are not the same species.

Can I keep one Otocinclus?

Don’t keep 1 Otocinclus. Always aim to keep five or more of them. The bare minimum is 3. Don’t go below 3, as this will stress them out.

Thanks for reading! If you have a minute, check out the list of plecos that can live in a 10 gallon tank from this article: What Plecos Can Live In a 10 Gallon Tank?

Asif Iqbal

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