How Fast Do Plecos Grow?

Have you just got a new pleco for your tank? Maybe you’re a newcomer to fish keeping and you have some questions about your pleco. Whatever brings you here, we are here to help.

Before giving you an answer to how fast plecos grow, we must first ensure everyone understands what a pleco is. 

What is a Pleco?

Pleco is the common name for the wonderful fish that is the Plecostomus. Plecos are a fantastic addition to any fish tank. They can live for up to a whopping twelve years.

There are a number of different species of Plecostomus, and the group belongs to the armored catfish family. They are a type of suckerfish and are known as bottom dwellers.

The suckerfish scavengers will eat almost anything and are popular because of the fact that they eat the algae that build up in tanks. They are like live-in cleaners, and are very fascinating ones at that! 

When you buy a baby pleco from your fish breeder or local aquatic supplies store, you may be surprised at how tiny they can be, especially when you may have seen some huge plecos!

Fear not, though, because plecos do indeed grow. In fact, in the wild common plecos can grow up to 24 inches long! In an aquarium tank, they may not quite reach these dizzying lengths, but don’t be surprised to find plecos around 15 inches in your tank. 

It is important to remember that because there are so many different species of pleco, each of them will be able to grow to different amounts.

For example, the bristlenose Plecostomos generally only reaches around 6 inches over several years - a vast difference from that of the common pleco who can grow up to 14 inches in that same time. 

How fast plecos grow depends on many factors, and lots of their growth happens within the first year of you having them.

This article aims to go into more detail about the growth of plecos, detailing the factors that may affect it. If you have just got a new pet pleco for your tank and you are wondering how fast it will grow, and even how big, keep on reading!  

For argument’s sake, we will be focusing largely on the growing habits of the common pleco, but with reference to other species. The common pleco is, as you may well guess, the most common choice for home aquariums. 

The first year of a plecos life 

As we briefly mentioned earlier in the article, the most growth done by your plecos is typically in the first year of their life. These are the formative times for your pleco.

Their growth rate is at its fastest during this time. That is not to say that they won’t grow anymore past the first year. Quite the opposite in fact. It just means that any growth after this first year will be at a much slower rate. 

Their growth during this first year does largely depend on a few factors. The tank environment that they live in has to be adequate for them in order for them to grow healthily.

We will discuss these factors in more detail later in the article. As long as the conditions in the tank are conducive to healthy growth, you can expect upwards of 3 inches growth from your pleco in this first year.

Some keepers even recall seeing 5 or 6 inches of growth in the first year. When you get them from the store or a breeder, they are typically just 2 to 4 inches long. So do keep in mind this growth before you buy them, ensuring your tank will be the right size for you pleco. 

Growth after the first year

We’ve put a lot of emphasis on that important first year of your plecos life. However, do not be fooled into thinking that growth will not occur after this. Remember what we said earlier on, under the right conditions, a Plecostomos can grow in an aquarium tank to around 15 inches.

This number is almost doubled for wild plecos! For plecos in your tank, growth after the first year is generally much slower and cannot be so easily noticed. As we mentioned earlier, plecos can live for around 12 years. However, they typically reach full size by around their fifth year. 

Factors that affect how fast plecos grow

As we have mentioned a few times, there are a number of factors that can affect the growth of your precious Plecostomus. The first thing to be noted is the size of the tank.

If the tank is too small, your pleco will not have enough room to reach its full size. Generally, for a common pleco, if you want it to grow to its full size, you will need a 150 gallon tank. Of course, if you do not want it to grow this big, a smaller tank will be fine. 

Another factor that needs to be considered when we think about how fast plecos grow is the food available for your fish. Plecostomus needs lots of fiber, so believe it or not, you can actually feed them vegetables such as zucchini, lettuce, shelled peas, cucumber, and spinach.

This fiber will help them grow and also help them remain healthy. They are of course bottom feeders, which means that you need to make sure their food can reach the bottom of the tank.

They do also eat the algae build up in your tank, as well as enjoying specially formed pellet food for plecos. They can also eat live food such as worms. Bloodworms are a favorite of plecos, as they can easily sink to the bottom of the tank! 

Lastly, it should also be acknowledged that plecos are nocturnal, so during the day, they need to be able to rest. Ensure they have lots of hiding places in your tank to ensure they are rested and healthy.

Like us humans, they also need resting time to grow. When you turn off your tank lights at night, that is when your plecos will appear. 


So, in answer to the question: how fast do plecos grow? We are happy to report that in their first year they grow rapidly, growing up to 6 inches on top of their 2-4 inches.

In the years that follow, growth slows down a little, but within 5 years you can expect to have a more or less full-sized Plecostomus.