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Freshwater   Fishes

Julii cory
(Corydoras julii)

Julii cory
Verified by the experts

Thanks to Kyllian. As stated by Horlack's scientific article
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Alternative species (click on the thumbnail to see the card)


Scientific name
Corydoras julii
Corydoras leopardus

Common name
Julii Cory
Julii catfish
Leopard catfish
Leopard corydoras
Leopard Cory/p>


what are its countries of origin?

Origin: Brazil, Colombia, Peru, Suriname
Biotope: Amazonian


what are the physical differences between males and females?

The male is smaller and slenderer than the female





what is the minimum volume for this species?

100 L / 22 imp gal / 26 US gal


what is the minimum volume for this species?

T°: 22 to 28°C or 72 to 82°F
pH: 5 to 7
Hardness: 1 to 15°dGH





what is the maximum size of this fish?

5 to 6 cm (1.9 to 2.4")


what is the average Longevity of this fish?

3 to 5 years

Living zone

in which area of the aquarium does this fish live?

Middle and depth


sociability of the species



How to feed this Corydoras?


How to feed this Corydoras?

The basic diet common to all Corydoras will suit perfectly well: the bottom pellets sold commercially.

This does not have to be the whole of its diet. For its balance, make regular contributions in tubifex, artemia, daphnia, worms (its favorite treat!) and plants (cucumber, zucchini, poached or boiled spinach, peas...). Remove uneaten food in the evening.

If your Corydoras are struggling to eat because other fish in the aquarium are faster, distribute their meal when the lights go out and watch if your Corydoras eat well.


What kind of behavior does this Corydoras have?


What kind of behavior does this Corydoras have?

This Corydoras is rather fearful. Note that it feels reassured by the presence of many of its congeners (see «Cohabitation»). However, this does not prevent it from being an active fish!

It will spend the majority of its time stirring the ground in search of food, with a peak of activity in the evening and at night. During the day, you will see it resting with its group, sometimes completely stacked on top of each other! It also likes to play in the current and swim against the current.

If your Corydoras are completely inactive during the day, it may be due to a problem of cohabitation (other species intimidate them), a too small number of individuals, an unsuitable aquarium or a current too weak. Check these points and you will see your Corydoras activate even during the day!

Even if the corydoras are very fearful, you can, with gentleness and patience, accustom them to your presence. For this, you must always make very slow and very calm gestures. When your corydoras do not flee you, it denotes a level of fulfilment, security and confidence well above normal!


Who can live with this Corydoras?


Who can live with this Corydoras?

The Corydoras julii will be able to easily coexist with many species that it never disturbs.

On the other hand, it is quite shy: it will be stressed and frightened by the presence of fish that are too big, lively or aggressive. For example, prefer to add tetra almonds that will make perfect roommates (pay attention to the water parameters in this case).

Cohabitation with a Common Pleco (30 cm or 12 inches!) is also to be avoided because it shares the same area of life and it can accidentally hurt a small Corydoras. Also, avoid putting them in competition with other bottom species for food (Loche, Ancistrus..) because the Corydoras always looses.

Of course, like all gregarious species, this Corydoras will need the presence of its congeners to flourish. So, plan a group of the same species of at least 10 (do not form your shoal with different species of Coryodras because they do not recognise each other). The fish will be more active and more present in the aquarium.Regarding this point, it is estimated that:
group of 6 to 8 individuals: strict minimum
group of 9 to 13 individuals: correct viability
group of more than 14 individuals: behavior similar to natural


How to breed this Corydoras?


How to breed this Corydoras?

The breeding of this species of Corydoras is more delicate than that of Corydoras aeneus or panda for example. The trigger mechanisms for spawning remain incomplete. Males are not always able to fertilise the eggs and the fragility of the fry makes the task even more difficult. As a result, the successful breeding of Corydoras julii is not very common, but remains possible for the more experienced aquarists.

The optimum age for breeding your corydoras is around 3/4 years old. Note that the older a female is, the higher the thickness of the eggs. They are thus more resistant and have a better chance of success, considerably increasing the number of fry. Before this age, you can get some fry all the same. If you want to make your corydoras breed, you understand the importance of installing them from the beginning in a suitable and well maintained aquarium, in order for them to live as long as possible, for a regular and successful breeding in quantity and in quality!

To try the breeding, have a specially dedicated aquarium (50 L / 11 imp Gal / 13 US gal). It will have a small filter and some large-leaved plants. Temperature at 23°C or 73°F, pH at 6/7 and hardness at 8°dGH.

Introduce the selected individuals (several males for 1 female) into the breeding aquarium and feed them intensively with various live prey. Renew the tank water to 50 to 70% with cooler water, which should trigger spawning. If this is not the case, repeat this step each day until the Corydoras spawn. Remove parents as soon as you observe the presence of eggs.

Another alternative is to spawn the fish in their aquarium and transfer the eggs to another tank to raise them.

The hatching occurs after 3 or 4 days (depending on the temperature, between 24 and 26°C or 74/79°F).

Fry food: infusoria, rotifers, artemia nauplii.

Its aquarium

Which aquarium for this Corydoras?

Its aquarium

Which aquarium for this Corydoras?

In general, two parameters are essential for the Corydoras aquarium: a non-cutting substrate and good filtration generating current.

Firstly the soil: it is imperative to use very fine gravel or sand (like beach sand). Indeed, it was discovered in early 2018 that sand played a key role in the oral hygiene of Corydoras. In addition, by swallowing this sand at full speed and spitting it by their gills in order to look for food, the Corydoras get rid of any parasites that could be fatal to them. It is imperative to avoid sharp ground like quartz, which damages the barbels of your fish, and is going to mutilate them completely.

Then the current: more than the length of the facade, it is especially the current that is important in an aquarium for Corydoras. Indeed, they are excellent swimmers and are... athletes! So, steer a strong current on the "middle" area of the aquarium, leave the bottom and the surface with a little less current. You will see your Corydoras feast on going swimming against the current in this area (if no other species intimidates them)! For everyone to rest, lower the intensity of the current during the night or stop it.

Corydoras's aquarium

As for decoration, if you want to recreate the natural environment of the Corydoras julii and promote its well-being, create a decoration with driftwood roots that will form beautiful hiding places and do not plant too much. You can add alder fruits and dried leaves to the aquarium, which will have a nice natural effect (you will have to renew them before they rot). You can leave on a proportion of 50 to 80% of sand beaches essential for the search, 30 to 40% of wood and 10 to 20% of plants. If your fish are comfortable in your aquarium, they will not hesitate to move. A Corydoras that does not swim is a fish uncomfortable in its environment.

For plants, choose sturdy plants with slow growth and broad leaves. As fertilizer is strongly discouraged in an aquarium in Corydoras, opt for plants that do not require this type of feed.

Whatever your choices in terms of layout, still keep enough sandy beach to Corydoras so they can search the substrate.

Corydoras are quite sensitive to water pollution. Make water changes of 10 to 20% of the volume per week.

Good To know

Find all additional information!

Good To know

Find all additional information!

There are over 200 species of Corydoras! Moreover, it should be noted a risk of hybridization between Corydoras of the same line.

Corydoras are often considered "cleaners". It is true that they are scavengers but they will never replace the work of the aquarist! For example, it does not eat their excrement or that of other fish. Thus, these fish are often bought for "practical" purposes (which remains questionable) to the detriment of their well-being. But you will understand, the Corydoras are nice fish that deserve all your attention!

Corydoras julii has no scales, which makes it particularly sensitive to salt, chemicals and drugs. This also requires maintenance, clean water and stabilized parameters (do not introduce Corydoras in immature aquariums). IT IS NOT RECOMMENDED TO PUT FERTILIZER in a container containing Corydoras. If you notice signs of stress, such as fast breathing and then lethargy (stay still, sometimes near the surface), immediately change 50% of the water (provide a good water conditioner). Be careful, the new water must have the same parameters as the tank, including the temperature. If you isolate your sick fish, it may wilt even faster. Try to stick the hospital tray to the main aquarium so that the sick Corydoras can see its congeners.

Like all Corydoras, this species is able to swallow an air bubble on the surface. Indeed, it is a kind of "intestinal" breathing that allows the fish to supplement its oxygen supply when necessary.

Its barbels are used to search the ground for food. It is because of these «whiskers» that Corydoras are called «catfish».

Corydoras are capable of killing a human in exceptional conditions. Pay close attention to their backbones or pectorals! Depending on the species, they have hemotoxic toxins, hepatotoxic toxins, neurotoxic, etc. Did you know that they do not have a natural predator? It is thanks to this weapon with which they are able to kill their assailant in a very virulent way. Even the piranhas refuse to attack the corydoras! Here is a small zoom on their dorsal or pectoral spines:
corydoras spines
As you can see, in the case of a sting, it is impossible to remove the real sting, it’s like a real harpoon. In addition, the corydoras injects at this time a maximum dose of toxins. Rest assured, the corydoras are very much scared, so it is rare that a situation of deadly contact happens. Most of the time, they will flee for such a situation to happen. But be careful when you put your hands in the water!

Use a large mesh net to prevent stuck in it.

Corydoras wink, which is fun to see!

Often confused with Corydoras trilineatus. Indeed, the motives of the latter can vary widely and sometimes resemble those of Corydoras julii. However, C.julii tends to have small spots, while C.trilineatus patterns form black lines like zebra.

It is considered a robust fish and easy maintenance, so it can be part of the species suitable for beginners.

Yours photos!


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