Cory Catfish Size Explained: How Big Do They Get?

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Knowing the expected size of a particular cory catfish is quite crucial for aquarists who are unsure if their tank is big enough or too crowded.

At least that’s how I felt a few years ago when I wanted to introduce a new school of six corydoras to my tank.

In this article, I’ll help you determine the expected size of different types of cory catfish, and show you what other factors can affect their growth rate and size.

What Is The Size Of A Cory Catfish?

The cory catfish’s length ranges between 1 and 4 inches, with 2.5 inches being the average.

To use a more practical example, these creatures are roughly the size of a nickel. Yet, this doesn’t apply to every cory catfish.

Technically speaking, fish never stop growing.^[1] You should also keep in mind the influence of external factors.

An aquarium’s conditions can either stunt a fish or enhance its growth beyond the norm. That being said, most cory catfish fall within the 1 to 4 – inch range.

The most prominent examples include:

Corydoras Species	Average Size
Panda Corydoras	2.5 inches
Bronze Corydoras	3 inches
Peppered Corydoras	2.5 inches
Albino Corydoras	3 inches
Emerald Green Corydoras	3-4 inches
Black Corydoras	2.2 inches
Pygmy Corydoras	1 inch
Sterba Corydoras	2.5 inches
Julii Corydoras	2 inches
Tail Spot Pygmy Corydoras	1 inch
Skunk Corydoras	2.5 inches
Bearded Corydoras	3-4 inches
False Julii Corydoras	2 inches
Salt and Pepper Corydoras	1.5 inches
Blackfinned Corydoras	2-3 inches
Horseman Corydoras	2 inches
Delphax Corydoras	3 inches
Robust Corydoras	3.5 inches
Smudge Spot Corydoras	1.5 inches
Barbatus Corydoras	5 inches
Green Laser Corydoras	2.5 inches

Some cory catfish may appear to exceed the 1 to 4 – inch size range. For example, the hoplo catfish can grow to an impressive 6 inches.^[2]

However, the hoplo catfish is not a true corydoras catfish but rather a close relative. The pair have a lot in common, including their physical features and personalities.

However, a hoplo catfish’s size and water requirements differ (64-82 degrees F, 6.0-8.0). It is less picky where the parameters are concerned.

Don’t assume that every fish whose features mirror those of a corydoras catfish is an actual cory catfish.

Competent retailers will warn you about a baby cory’s maximum size before you buy it.

If that maximum size exceeds the average cory catfish size, confirm that your fish of choice is a true cory catfish before buying.

**Emerald Green Corydoras are slightly above average and can reach up to 4 inches in length.**

How Long Do Cory Catfish Take To Reach Full Size?

On average, it takes a cory catfish between 8 and 12 months to reach its full size. This is true for both males and females.

Nevertheless, a fish’s size and growth rate are susceptible to numerous factors, for example:

1. There Is Variation Within The Species Itself

It can take young cory catfish ten weeks to attain an inch in length.^[3] After that, their growth rate will slow, so much so that they won’t reach their full size for another nine months.

Some cory catfish will take more than nine months to reach their full length.

Others will accomplish this task in a shorter period. Like human beings, you cannot predict a cory catfish’s response to external stimuli.

2. Genetic Abnormalities May Play A Role

Don’t expect cory catfish to grow to the same size. For instance, panda cory catfish have an average length of 2.5 inches.

Don’t panic simply because your panda cory catfish are only 1 inch. Genetic anomalies can enable the same type of cory catfish to grow to different lengths.

This is also true for the growth rate. Don’t assume that a catfish is stunted in its growth because it has stopped growing or is growing slower than other fish of a similar type in the tank.

There are two additional considerations in mind:

Gender – Female cory catfish generally grow to larger sizes than their male counterparts. From head to tail, females may be 0.2 inches longer than males.

Type – Some cory catfish types are larger than others. Learn to differentiate between the types based on their colors and features. This will allow you to predict their growth rate and maximum size.

If you’re not familiar with the different types of cory catfish, here’s a great YouTube video to walk you through it:

3. External Stimuli Have A Huge Impact

Fish are vulnerable to external stimuli that shape their growth rate and maximum sizes. Experienced aquarists tend to obsess over the following:

Food

Food is the most important consideration. Fish can stop growing if you force them to tolerate low-quality meals.

You don’t have to obsess over complex diets. Experts in this field are constantly discovering new ways of using a fish’s diet to boost growth.

For instance, a paper in Environmental Health Matters wanted to understand the connection between a fish’s growth and the energy of the prey it consumes.^[4]

The researchers theorized that a predator that consumed prey with significant amounts of energy would enjoy greater mass growth. The results of their study lent some credibility to this theory.

Meanwhile, researchers from the University of Maryland Center for Environmental Science revealed in a 2012 paper that probiotics could enhance growth in fish.^[5]

But again, you don’t need probiotics to ensure that your cory catfish attains its maximum size. A conventional fish diet is sufficient.

Pro tip: Cory catfish need to eat food that sinks to the bottom. Floating food forces them to swallow air, and possibly develop swim bladder disease.

Water Quality

Nothing stunts a fish’s growth faster than low-quality water.

Scientific studies have analyzed this concept on various occasions. Take this paper in ‘Fisheries and Aquatic Sciences’, which looked at the impact of physio-chemical parameters on tilapia growth in Teso, Uganda.^[6]

They noticed that increased pH, ammonia, and conductivity reduced the growth rate of fish in earthen ponds.

Expect a similar response from cory catfish. Maintain the correct pH, temperature, and hardness to avoid cases of stunted growth.

Tank Size

In case you’re wondering, the answer is no. Cory catfish do not grow to fit the size of the tank. Experts debunked that myth a long time ago.

Cory catfish do not control their size or growth rate. Therefore, they cannot choose to stop growing simply because their tank is small.

However, conditions will deteriorate rapidly in a small tank, exposing cory catfish to diseases, infections, and bouts of stress that limit their growth.

Predators

S.D. Connell (School of Biological Sciences, University of Sydney) released a study that showed the drastic impact predators could have on a fish’s growth.^[7]

The pressure they exert can limit a fish’s ability to attain its full size.

Cory catfish are particularly vulnerable because of their downturned mouths and timid personalities. They are not in a position to fight back against bullies.

For that reason, I suggest avoiding aggressive species like oscars, angelfish, rainbow sharks, tiger barbs, discus, etc.

More suitable tankmates for cory catfish may include guppies, neon tetras, shrimp, loaches, plecos, and even snails.

**Rainbow sharks occupy the bottom of the tank and are quite aggressive – you must not mix them with cory catfish.**

Which Cory Catfish Is The Smallest?

Pygmy cory catfish (Corydoras pygmaeus) is the smallest type (0.75 to 1 inch).

This is why aquarists with a relatively small tank (under 20 gallons) prefer this species, as they do not take up too much space.

Next, you have dwarf cory catfish (Corydoras hastatus), which grow to about 1.5 inches. They are also an ideal choice for a small container.

**Pygmy corydoras are the smallest species of cory catfish and are ideal for relatively small and crowded tanks.**

What Is The Minimum Tank Size For A Cory Catfish?

Ten gallons is a decent starting point. However, you should aim for 20 gallons to be on the safe side.

Keep in mind that cory catfish are shoaling fish. You can’t keep one or two. It takes a group of six or more to keep the cory catfish happy.

You need a tank that can comfortably house a group of six cory catfish. A 5-gallon bowl won’t do.

Don’t forget that some regions have regulations that punish individuals for mistreating their pets.

Your local authorities may penalize you if they conclude that keeping a group of six cory catfish in a 5-gallon tank amounts to cruelty.

Conclusions

Cory catfish are relatively small. They typically range in size from 1 to 4 inches, with 2 to 3 inches being their average length (head to tail).

The smallest type is the Pygmy catfish (Corydoras pygmaeus), which usually does not exceed one inch. This is the recommended species for small aquariums.

Aside from the particular subtype, environmental factors such as feeding and water conditions may determine the final size of your corydoras as well.