How Fast Do Algae Eaters Grow

How Fast Do Algae Eaters Grow?

Algae eater fish are a good addition to your tank whether it be for pet-keeping purposes or to stave off pesty algae growth. Just like any other pet, they require good care to reach their full size and to stay in good health. When providing this level of care you may still be tempted to ask: how fast do algae eaters grow?

Depending upon the type of algae eater and tank conditions like temperature, space, and food availability impact just how fast your algae eater will grow. With this in mind, you may have a fully grown algae eater in 6 months or it could take a few years.

In this article, we’ll cover everything pertaining to algae eater growth from just how big they get to how big specific species get and whether they grow to tank size.

How Long Does It Take Algae Eater Fish To Grow?

A few factors determine just how big your fish will grow and in how long. Some of these are listed below.

The Individual Fish’s Genes

This is the case for all species. Some individual fish have genes that result in faster growth while some will inevitably grow slower. Similar is the reason why some grow to be so big while others may remain small throughout their lifespan. 

Availability Of Food 

With a greater abundance of food, algae eater fish have a greater quantity of proteins and microelements readily available for them to fast-track their growth.


Setting your tank to a higher temperature (within the appropriate range) can boost metabolism and growth among your algae eaters, speeding up their growth rate. Any temperature out of range though would stunt growth due to decreased tolerance to water constituents.

Available Space

Having the right amount of fish in your tank could be the difference in having fully grown algae eaters or those with stunted growth. Overcrowding results in stunted growth as a means of self-correcting a situation that is meant to benefit the whole system. 

Being cognizant of the type of fish you put together with algae eaters is also important since pheromones off from these other fish can also lead to growth inhibition.

Thus, optimizing the number of fish (and type of wish) in your tank can positively impact the growth as well as the growth rate of your algae eaters.

Keeping these factors in mind, you could have a fully grown algae eater within as little as 6 months. For less than ideal conditions, your fish could take anywhere from 1.5 years to even longer to become fully grown.

How Big Do Algae Eaters Get?

Algae eaters range in size, growing from 2 inches to up to 2 feet, depending on the species. Siamese Algae Eaters, one of these species, grow up to 6 inches in length. They tend to be sold in the early stages of their growth cycle when they measure only 3 inches in length. Juveniles of this species are sold when they grow to a length of about three inches.

Other common algae eaters like the Chinese Algae Eater and the Siamese Flying Fox species can grow up to 11 and 6 inches respectively. The Sailfin Pleco falls under the larger category of alga eater fishes with a maximum length of 19 inches. 

How Fast Do Siamese Algae Eaters Grow?

The Siamese Algae Eater on average lives for 10 years. Their lifespan can be extended past this if kept in optimal conditions; for this a well-maintained tank is key. It takes about 6 months to 2 years for Siamese Algae Eaters to reach their maximum size. 

Factors such as food quality and quantity as well as tank conditions (temperature, pH, oxygen levels, etc.) play a role in determining their maximum size as well as the time frame to attain it. Keeping these at the ideal levels can help speed up their growth and similarly sub-par conditions may hinder their growth rate.

Do Algae Eaters Grow To Tank Size?

Fish “growing to tank size” is simply a myth. What really happens is that when fish are moved from a smaller tank to a larger one, they experience a growth spurt as a result of improved living conditions, creating the impression that they “grew to the size of the tank” and are now growing again to the size of the larger tank.

While it may seem enticing to keep many algae eater fish in a tank to create an optimal aquatic environment with the added benefit of them keeping the tank clean, you actually need to be much warier of the number of fish you keep.

The ideal tank size for your algae eater depends on the number of fish you plan on keeping and the maximum size they will grow to in the adult stage of their life cycle.

2 fish could make do in a 2.5-gallon tank, 3 – 5 fish would require a 9 – 15 gallon tank, 5 – 8 fish would need a 20 – 55 gallon tank contingent upon the size of the fish.

Generally, a 20-gallon tank should suffice for algae eaters that grow to a maximum length of 6 inches. Larger species would require a 75-gallon tank at the least. So while “growing to tank size” may not be a real concept, tank size still matters greatly when it comes to ensuring the health, growth, and productivity of your fish.


Algae eater fish is a popular choice for aquarium hobbyists looking to both grow their fish collection while ensuring a cleaner tank (owing to this species’ algae consumption). Depending on the species and tank conditions algae eater fish can take anywhere from 6 months to a few years to reach adult size. 

Algae eaters can be of a length ranging from 2 inches to 2 feet. Siamese Algae Eater fish, a common variety, take 6 months to 2 years to grow to a full adult size of 6 inches. The size and rate of growth aren’t factors that are determined by concepts like “growing to tank size” although tank conditions are essential in the sustained health of these fish.