Corydoras, commonly known as Cory cats, are a popular fish for home aquariums. Their peaceful nature, energetic schooling behavior, and ability to clean algae make them an excellent choice for community tanks. However, corys are shoaling fish that prefer to be kept in groups. This raises an important question for aquarists: how many corys can be housed together in a standard 10-gallon tank?
The One-Inch Per Gallon Rule
A common guideline in the aquarium hobby is the “one-inch per gallon” rule. This states that you can house one inch of adult fish per gallon of water in the tank. For example, a single 3-inch fish could be kept in a 3-gallon tank. Some aquarists interpret this rule to mean you can add one inch of cory cats per gallon to a tank. However, this rule has some limitations when applied to corydoras.
Corys are active bottom dwellers that spend a lot of time scavenging along the substrate. They need horizontal swimming space even more than water volume. And being shoaling fish, they should be kept in groups rather than singly. The one-inch per gallon rule doesn’t account for these special needs of cory cats. While useful as a general guideline, it has to be adjusted for specific types of fish.
Recommended Aquarium Size for Cory Cats
Most aquarium experts advise keeping corydoras in a minimum 10-gallon tank, though a 15-20 gallon or larger aquarium is better. This allows them adequate floor space to explore and move around. In a cramped tank, they may become stressed which can lead to disease. A 10-gallon tank is only sufficient for a small group of corys. The larger the tank, the more corys that can be added.
Minimum Cory Group Size
Cory cats will be happiest and healthiest when kept in a group of 6 or more of their own kind. Having sufficient numbers allows them to exhibit their natural shoaling behavior. In a small 10-gallon aquarium, most experts recommend keeping just one group of 6 corys. Mixing multiple types of corys or other bottom dwellers will quickly fill up the limited space.
Stocking Considerations for a 10-Gallon Cory Tank
In addition to the group of 6 cory cats, a 10-gallon tank has room for some other peaceful community fish. Here are some important stocking considerations:
- Choose fish that occupy different areas of the tank, such as mid-level swimmers and surface dwellers.
- Avoid fish with very long flowing fins that may be nipped by corys.
- Do not overstock. Fully stocked tanks require more maintenance.
- Get juveniles instead of adults to maximize growth potential.
- Introduce corys and other fish gradually to avoid aggression.
Suitable Tank Mates for Corydoras
Here are some examples of suitable tank mates for a group of 6 cory cats in a 10-gallon aquarium:
- 8-10 neon tetras or other small tetras
- 6-8 guppies, platies, or mollies
- A pair of dwarf gouramis
- A dozen ghost or cherry shrimp
- African dwarf frogs
The combinations above should make for a harmonious mixed community without overcrowding the 10-gallon tank. Be sure to research if any species you choose have special requirements in terms of water parameters and diet.
Water Conditions for Keeping Corydoras
While adaptable to a range of water chemistries, corys prefer soft, mildly acidic water. Here are some general guidelines for cory cat water conditions:
- Temperature 72-79°F
- pH between 6.0-7.0
- KH 1-5 dGH
- Soft to moderately hard water
Since corydoras are sensitive to poor water quality, weekly partial water changes of 20-30% are recommended. Using an aquarium test kit to monitor ammonia, nitrite, nitrate, and pH will help maintain ideal cory cat water parameters.
Cory Cat Tank Setup Tips
To make corydoras feel secure and display their best behaviors, provide the following tank setup for a 10-gallon cory habitat:
- Fine gravel, sand, or smooth bare bottom substrate
- Several hiding places like caves, tunnels, and plants
- Subdued lighting and plenty of shady spots
- Driftwood, rocks, pipes for grazing surfaces
- Low to moderate water flow
Avoid sharp decorations and substrates that can damage cory barbels. Create open sandy areas for sifting and foraging. Use a quality aquarium heater to maintain water temperature in the proper range.
Best Cory Cat Foods and Feeding
In the wild, corydoras catfish forage along the tank bottom for fallen food items, small insects, worms, and plant matter. In a home aquarium, they should be fed a varied diet consisting of:
- Sinking pellet/wafer foods
- Frozen or freeze-dried brine shrimp, bloodworms
- Blanched vegetables like zucchini, cucumber
- High-quality flakes that reach the bottom
- Occasional live or frozen foods as treats
Feed corys small amounts 2-3 times per day. Only provide what they can consume within a few minutes. Uneaten food should be promptly removed to maintain water quality. Target feed them sinking foods or use feeding dishes on the bottom. This allows them to forage more naturally and prevents faster fish from hogging all the food.
Best Commercial Cory Foods
Some top-rated foods for corydoras cats include:
| Food Type | Examples |
|---|---|
| Sinking pellets/disks | Hikari Sinking Wafers, Omega One Shrimp Pellets, Fluval Bug Bites, Tetra Pro Algae Wafers |
| Sinking granules | New Life Spectrum Small Fish Formula, Northfin Veggie Formula |
| Gel foods | Repashy Soilent Green, Fluval Bug Bites |
Avoid flake foods that float at the surface. Look for high-quality ingredients with added vitamins and minerals. Softer foods may need to be crushed to an appropriate size for cories to eat.
Cory Cat Tank Maintenance Tips
To keep your cory cats healthy, be diligent about tank maintenance. Important habits include:
- Test water weekly and do partial water changes as needed
- Gravel vacuum substrate to remove debris
- Clean or replace filter media monthly
- Trim plants and remove algae as needed
- Wipe glass to remove diatoms and spot algae
- Ensure adequate oxygenation and surface agitation
Dirty tanks compromise corydoras health. Monitor ammonia, nitrite, nitrate, and pH levels closely. Use water conditioner to remove chlorine and chloramines whenever changing water. Keep tank surfaces clean and equipment in good working order.
Signs of Stress in Cory Cats
Watch for these common signs of stress or illness in cory cats:
- Loss of appetite
- Lethargy, hanging at water surface
- Clamped fins
- Rapid gilling
- Discoloration, lesions on body
- Gasping at bottom
- Hiding more than usual
Rapid changes in water parameters, poor diet, overcrowding, aggression from tank mates, and dirty water can cause stress responses. Try to identify and remedy the underlying issue. Use quarantine tanks to treat any sick fish. Consult an exotic pet veterinarian for stubborn health problems.
Interesting Facts About Cory Catfish
Here are some fascinating facts about corydoras catfish:
- There are over 200 recognized species of corydoras
- They communicate via body postures and pheromones
- Most corys breed readily in home aquariums
- Males often have thicker, longer barbels than females
- They are native to freshwater streams in South America
- Cories have a max lifespan around 5-10 years
- Brochis and Aspidoras catfish are close relatives
- Their barbels help them find food in muddy waters
- Cory eggs are often attached to plants or decorations
- They gulp air from the surface to breathe when needed
With proper space and care, cory catfish make engaging, active additions to community aquariums. Their unique behaviors and substrate sifting bring new life to the tank bottom!
Conclusion
To summarize key points from this article:
- The standard 10-gallon tank can reasonably house 6 cory cats
- Provide at least 6 corydoras to allow natural shoaling behavior
- Cories need bottom space more than volume, so bigger is better
- Tank mates must be peaceful, avoid bottom dwellers
- Soft, acidic water with moderate current suits corys best
- Feed a varied diet with plenty of sinking foods
- Maintain excellent water quality and tank hygiene
- Corydoras make active, social additions to community tanks
When setting up a 10-gallon cory cat aquarium, focus on providing a spacious, healthy environment tailored to their needs. With the right tank conditions and compatible fish, corys will thrive and display their natural behaviors.
