Corydoras are some of the best fish you can put in a freshwater aquarium.
Peaceful, social, and big personalities.
Plus, watching them swim together and bunch in to eat an algae wafer always makes for an entertaining time. (By the way, this is the brand of algae wafer I recommend for them and a bunch of other fish on this list.)
But what can you put in an aquarium that won’t bully them?
Rasboras are one of the most popular peaceful community fish in the hobby. (And they deserve that popularity.)
They come in a variety of colors, don’t require a lot of special care, and are hardier than the more popular neon tetras. (Due to bad genetics in the tetras.)
They do like to be in a group, so 6 should be the bare minimum you should keep. 10 or 20 would be better if you have the space in your aquarium.
And if you don’t like the way one rasbora looks, there is always another with a different aesthetic.
Take a look at these strawberries, for example:
Rasboras in general don’t require a lot of space, so any tank that’s large enough to fit a school of corydoras is large enough that you should be able to fit at least one school of rasboras as well.
Different rasboras that are shaped similarly will typically school together, so you can mix and match to a limited extent. Ones with different shapes, like harlequins and neons, won’t usually school together, and you’ll want to get 6+ of each.
They will eat most tropical flake or pellet foods, as long as the food is small enough to fit in their mouths.
Here are a few varieties of rasbora worth considering:
- Neon Rasboras
- Mosquito Rasboras (AKA Chili Rasboras)
- Galaxy Rasboras (AKA Celestial Pearl Danios)
- Strawberry Rasboras
- Harlequin Rasboras
- Scissortail Rasboras
Overall, I would highly recommend one or more types of rasbora for a tank with corydoras.
Otos are a great community fish that – like corydoras – are a type of catfish.
Otos excel at eating diatoms (brown algae), and are one of my favorite fish from my aquarium.
They tend to spend all day moving from one spot to the next in search of food. Then, they’ll have bursts of activity where they swim around the tank and chase each other.
Feeding them can be a bit difficult once your aquarium runs out of the types of algae they eat, as they tend to ignore algae wafers and other types of food.
Aquarists have had luck, however, with feeding blanched zucchini and/or cucumber. (You can do this pretty quickly in the microwave.)
They are an entirely peaceful fish, and they’ll get along nicely with cory catfish. (Here are some other fish otos get along with.)
Mollies are another species that will get along well in a tank with corydoras.
They come in a variety of shapes and colors, and they are a very popular livebearer.
They are often bred overseas in brackish water, however, and then just dumped into freshwater at the local fish store.
Because of this, you may have trouble getting them to thrive in your aquarium. (Due to health issues caused by this transition.)
If you’re getting mollies, your best bet is to find someone that breeds them in fresh water. Otherwise, just look for the healthiest ones you can find at your local store, and avoid any that look sickly or that have clamped fins.
They will reproduce readily in your aquarium, so you should have a plan to deal with them when their numbers increase beyond your tank’s capacity. (Or have other fish in your aquarium, which will likely eat a lot of the young.)
Another type of livebearer that works well with corydoras (as most of them do) is the endler.
Endlers are a different species in the same genus as guppies, and a lot of the care for them are the same.
They like hard, slightly alkaline water, so if you have soft acidic water, they may not work for your aquarium.
If your water parameters are correct, however, you’ll be rewarded by one of the best looking small fish in the hobby. The males will spend their days dancing and showing off for the females.
Just make sure you keep 2-3 females for every male to give the ladies a bit of a break.
Like mollies, they will reproduce, so you can start off with a few breeding pairs and let them multiply from there. (Instead of dropping a bunch of money on a huge school from the start.)
If you’re interested in endlers, check out my endler’s livebearers care guide.
A third type of livebearer is the platy. If you’re tempted to keep goldfish with your corys (don’t), these might be a good substitute for you.
They stay small, have similar coloration to goldfish, and make a great choice in tanks 10 gallons and up. (Don’t try that with a goldfish.)
There are multiple variations of platies, so make sure you get the right ones for your tank, as swordtails get larger, need a bit larger of a tank, and can be a bit less peaceful than regular platies.
They are relatively easy to feed and eat most types of food. I notice mine picking around the bottom of the tank a lot, so I prefer to feed Omega One Algae Wafers (link is to the brand I use over at Amazon).
They like them so much that they may prevent your plecos and cories from eating them, so you’ll need to be careful about how you feed. I prefer breaking them up and spreading them in different areas of the tank so it’s hard for them to be monopolized.
As mentioned above, swordtails are closely related to platies, and can interbreed with them.
Because of this, if your local fish store (or anyone they got the fish from) kept their platies and swordtails together, you’re likely to get hybrids of the two.
It also means that a lot of the care and feeding tips are the same. You will need at least a 20 gallon tank, however.
The sword on the males’ tails looks great, but personally, I would rather have platies because they’re smaller and you can keep a few more of them in a tank when compared to sword tails.
Danios are a great group of fish to keep with corydoras. They are peaceful, like slightly cooler water, look great, and come in a variety of colors.
Their base color is a reddish silver with blue stripes running down their sides.
They get to be 2″ in length, and they do best at 75F, but they are said to be able to survive in water between 70-90F. (The upper end of this range may cause shortened lifespan.)
They can get a bit fin nippy if they are kept by themselves, so you’ll need to keep them in groups of at least 6 danios per tank. The more the better
If you don’t like their base coloring, you also have the option of getting different colored danios from glofish (through your local fish store).
Neon tetras are one of the most popular fish in the hobby, and they deserve that reputation.
They are peaceful, relatively easy to care for, and go perfectly in a tank with cory catfish.
They do have a problem with neon tetra disease due to poor genetic stock, but other than that they’re a great fish for beginners.
They also don’t do well with aggressive fish, so you’ll want to keep them in a tank that only has other peaceful species.
As far as temperature, they like water between 70-80F, so they should be fine for a tank that already has corydoras in it.
There are quite a few gourami that will do well with corydoras, but honey gourami are the only ones that I recommend keeping.
A lot of the gourami species can be aggressive, and dwarf gourami have quite a few health problems that are difficult to treat and lead to early death.
Honey gourami are peaceful and relatively hardy, and you can keep a pair of them easily (or more, but it’s best to only keep 1 male in the group, as they can be a bit territorial with other males when spawning).
They are quite shy and generally won’t bother other fish, so there shouldn’t be any issue between them and your corydoras. You will want to make sure there are plenty of hiding spots in the tank, however.
If you want an excellent looking bold red fish, the cherry barb is another good choice.
They get along with corydoras so well that it’s not uncommon to hear stories from other hobbiests about their cherries schooling with their corydoras and even eating their algae wafers like they’re one of the pack.
They should ideally be kept in groups of at least 6. If there are fewer of them they may get a bit aggressive, but it’s also possible that they’ll just school with your corydoras instead.
I’ve not personally had success with cherry barbs, but they’re said to be a hardy fish as long as you provide the right conditions for them.
Moving over to inverts for a moment, shrimp are another great option for a tank with corydoras. Amano shrimp are notable among shrimp because they’re exceptionally hardy and are one of the few things that eat hair algae.
I’ve found shrimp to be a bit difficult to keep alive because of my hard water, but Amano shrimp are one of the species that do well in my aquarium.
They are very productive creatures, and you can find them scouring the tank for debris to eat day and night.
They do require a bit of a lower PH and softer water, but if you can provide that for them, they’ll reward you with an excellent tank mate for your cories.
They also eat the same algae wafers that you would feed to corydoras, so they are extremely convenient.
Mystery snails are another bulletproof invert that can be kept with most peaceful community fish – including corydoras.
These guys are my favorite part of the aquarium, and they can be seen driving around the tank eating things most hours of the day. (They do take periodic cat naps throughout they day.)
They will eat certain types of algae, dead plant matter, dead fish, and leftover food, so they make an excellent addition to your cleanup crew.
(If your tank is too clean, you’ll want to provide them an algae wafer to eat when you feed your cories.)
They also don’t try to escape your tank like nerite snails do.
Hatchetfish are another good species that will work with corydoras, as long as you have at least a 20 gallon long tank.
They have a very distinct look that I, personally, find to be quite endearing. They’re also extremely peaceful, so they’re great as long as you don’t have anything to bully them.
They live at the very top of your aquarium, so they occupy a space that not a lot of other fish will swim in.
Because of this, you’ll want food that stays at the top of the tank. Here are a few good options:
- Wingless fruit flies
- Tiny live crickets
- Freeze dried daphnia
- Freeze dried bloodworms
Flakes should work as well, but you’ll want to make sure they’re eating enough before the flakes start to sink.
Kuhli loaches are another good option with corydoras, especially if you’re looking for something that resembles an eel.
Like cories, you’ll want to keep 3-6 of them.
They are peaceful fish, so they’ll do well with your corydoras as long as you have enough floor space at the bottom of the aquarium to keep them both happy. A 20 long or bigger should be fine.
A sinking pellet designed for carnivorous fish, such as sinking shrimp pellets, is best to feed kuhlis.
Red Cherry Shrimp
Finally, red cherry shrimp are another option if you’re looking for a colorful addition to your cory tank.
Like other shrimp, they are peaceful and will get along nicely with any fish that doesn’t try to eat them.
They’re also a good addition to your cleaning crew and will eat most leftover food and dead plant matter from the bottom of your aquarium.
Red cherry shrimp are one of the species of shrimp that will breed in a freshwater aquarium (unlike Amano shrimp), so you have a good chance of getting more once you put your initial colony in.
By the way – if you want to see more peaceful fish that could work well in your community tank, check out my post on neon tetra tank mates.