Corydoras FAQ


Corys are one of the most misunderstood fish kept in aquariums & there are often lots of questions about them so I thought I'd try & answer a couple of the most frequently asked ones.

Q. How many corys should I have & will different ones stay together?

A. Corys are a shoaling fish & as such should be kept in groups of 6+ of their own kind. It might seem like a good idea to have 2 albino, 2 Panda, 2 peppered etc but it's really not, yes they may seem happy to stick together but that is only because they have no choice.
You wouldn't keep a group of 2 neons, 2 Rummynose, 2 ember tetra etc & expect them to school happily together just because they're all tetras.
Keeping them in proper sized groups of their own kind you will see much more natural behaviour & isn't that what we all want to see in our tanks?

Q. What do I feed them?

A. They're often thought of as being part of the clean up crew & will be ok on any scraps that fall to the bottom or that they're algae eaters. They get little to no nutrition from algae or veg as their digestive systems are not set up to process it efficiently.
Yes they will eat any food that hits the bottom but corys need their own diet which should consist of frozen or live bloodworm if you can get it, brine shrimp, daphnia, etc and catfish pellets or wafers.

Q. What substrate should I keep them on?

A. Corys are sand sifters, they take a mouthful & sift it through their gills retaining the food & letting the sand fall through.
Have a look at this video, not mine but shows how the sand is expelled through the gills.

They can be kept on gravel but use a fine grade & make sure it's smooth with no sharp edges. If you've looked at the video I hope you'll choose sand for them there's nothing nicer than seeing your corys head first in the sand looking for morsels of food.

Q. What tank size do corys need?

A. There are several species of smaller corys the most commonly seen are C. Pygmaeus, C. Habrosus, & occasionally C.Hastatus, a group of 6 could be comfortably kept in a 15 US gallon.
Pygmys & Hastatus tend to spend a lot of their time in the middle levels so that should be taken into account when choosing tankmates.
Other small species not often, if ever seen are C.Gracilis, C.Cochui, if you see these snap them up!

There are currently around 400 species of corys (new ones are still being found) most don't exceed 3", the larger species I'd suggest a 20US gallon (75 litre) some of the smaller species could be kept in a 15US gallon (60litre) of course bigger is always better.
For more information on various species size have a look on Planet Catfish

Just a word on temperature requirements, most corys are happy in the mid range, around 24C whilst peppered require much cooler temperature 20-22C. SterbaI like warmer temperatures 26C+ & are often kept with Discus for that reason.
Some other species that have wider ranges & can handle higher temperature are C.adolfoi, C. Splendens (emerald brochis), C.duplicareus, C.haraldschultzi, C.gossei, C.suessi, C.oiapoquensis & C.aenus
There are of course other species for warmer & cooler water, I've just mentioned a few.

As you've probably guessed they're my favourite fish & I want to help them live long (15-20+years) & happy lives in everyone's tanks.

Some cory myths debunked by Ian Fuller
The legend of the Cory

Claire Bear

I love my cory's and supplement with worms, shrimp, even thawed salmon when there is extra!
I do tend to think of them as clean up crews!
Great information, thank you!


Applause !!!!


Brilliant! A great spot to guide people to as well


Awesome! Been watching Belgium -USA for the last hour and a half, still 0:0 your video is certainly more exciting.
Mods, Is it possible to turn Coradee's post into a sticky?


Mods, Is it possible to turn Coradee's post into a sticky?

Yes please!!x



Coradee Thanks for writing this up.
It should help a lot of people looking for information about cories.

Perhaps you could add something about tank sizes?


Do all corydoras have bony scutes?


Do all corydoras have bony scutes?

Yep, that's where they got there name from!!!


Coradee, could you add all of the warm water cories to this if you have time?
I think that'd be very helpful. Great write up!


Helped alot


Thank you, Coradee. Excellent information. A month or so ago, I had started a thread entitled "How many Rasboras?"...or something like that, and mentioned that I had 3 False JuliI Corys. You recommended I add at least 3 more. I posted an update to that thread a week or so ago; you may wish to read it. Anyway, I did complete the school and now have 6 of these sweet little fish. They are so fun to watch & seem happy. Problem: DFG who races to their food pellets. Unfortunately, I started this aquarium not knowing I would be getting Corys and have medium-sized gravel, another problem. I try to distract Mr. Gourami with flakes while I drop pellets on the other side of the tank, but Gourami always dashes over to the pellets, nudging them, breaking them up and eating them. I worry that my Corys are not getting enough to eat. Any ideas? (I tried using a little terra cotta dish - Mr. Gourami simply nudged the pellets out and into the substrate, and when I vacuumed I discovered a LOT of food left in that area. Any suggestions?

william holland

Informative thread, wish I'd checked it earlier. I was told by the young guy at the aquarium shop that it was not an issue to get different types of cories in putting together a 6 cory group for my 55gal. So I got a pair each of three different types. I've noticed they remain paired, only in the presence of the other cories randomly since they all occupy the same territory. Well now I see the clerk's advice was misplaced.


I think maybe the specifications for tank size should include the minimum length of the aquariums, instead of just saying "15-gallon" or "20-gallon." That way, newbies will know that a 15-gallon hexagon tank won't work well for cories, and that a 20-gallon long is better for most medium to large cories than is a 20-gallon high.


Great post, I'd expand the first post and include a bit about anatomy and cory behaviour.

Things like be careful netting them as the spines/spikes in their fins can get caught in a net. I've not had this happen to me with corys, but I've encountered this with a bristlenose.

Normal behaviour that confuses people like racing up and down the aquarium walls, gulping air in from the surface of the water.

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