Why Corydoras Are the Best Community Fish
Corydoras catfish (often called "cory cats" or simply "corys") are armored catfish from South American rivers. There are over 150 known species, ranging from the common Corydoras paleatus (peppered cory) to the striking Corydoras sterbai and Corydoras panda. All share the same peaceful temperament and active, social behavior that makes them favorites worldwide.
Unlike many bottom-dwellers, Corydoras are diurnal — they are active during the day, constantly moving along the substrate, searching for food, and interacting with each other. A school of 6 Corydoras in the right setup is more entertaining to watch than many "showpiece" fish.
Corydoras also perform a useful function: they clean up uneaten food that sinks to the bottom before it can rot and raise ammonia levels. They are not magic cleaners and cannot substitute for regular gravel vacuuming, but they genuinely reduce waste accumulation.
The Essential Rule: Keep Them in Schools
The single most important rule for Corydoras care is this: never keep fewer than 6. Corydoras are schooling fish that feel safe only in groups. A lone Corydoras will hide constantly, refuse food, become stressed, and usually die within months. Two or three will be timid and inactive.
A group of 6 or more changes the dynamic completely. They school together, forage actively across the entire tank bottom, play, and display their full range of natural behaviors. Some Corydoras species should be kept in even larger groups — Corydoras habrosus and other dwarf species do better in groups of 10 or more.
Keep the same species together in your school. While different Corydoras species will coexist peacefully, they do not school cross-species. Six peppered cories and six bronze cories = two separate groups of 6, not one group of 12. If you have limited space, choose one species and keep 8-10 of them rather than a mixed group.
- ✦Minimum group: 6 of the same species
- ✦Larger groups (10-15) show more natural behavior and are less stressed
- ✦Different species coexist but do not school together
- ✦Add all fish in the school at once — adding new fish later may cause the established school to reject newcomers
Substrate: Sand Is Non-Negotiable
Corydoras feed by sifting through the substrate, using their sensitive barbels (whiskers) to detect food. Gravel with sharp or rough edges damages these barbels — once damaged, they rarely heal and the fish can no longer feed properly.
Fine sand (0.5-1mm grain size) is the only substrate that allows Corydoras to behave naturally. Pool filter sand, river sand, and aquarium-specific sands like Caribsea Super Naturals are all suitable. Avoid very fine sand that compacts — compressed sand becomes anaerobic, producing toxic hydrogen sulfide gas.
If you already have gravel in your tank and want to add Corydoras, either replace it with sand or create a sand section at the front of the tank. Corydoras will find the sand area and spend most of their time there. Smooth river pebbles are a compromise option — they do not cut barbels, though Corydoras still cannot sift through them naturally.
Water Parameters and Temperature
Most common Corydoras species prefer 22-26°C — on the cooler side for a tropical fish. This makes temperature management important in Cambodia. Species like Corydoras sterbai, Corydoras duplicareus, and Corydoras schwartzi are naturally from warmer Amazonian rivers and tolerate up to 30°C better than the common Corydoras paleatus or Corydoras aeneus.
If your tank runs at 28-30°C in Cambodia's climate without cooling, choose warm-tolerant species: Corydoras sterbai is the top recommendation, widely available and colorful with its orange-spotted pattern. Corydoras aeneus (bronze cory) is a good budget option that handles warmth reasonably well.
pH should be 6.5-7.5 for most species. They prefer soft to moderately hard water. In Phnom Penh and Siem Reap, tap water tends toward the harder side — add peat moss or Indian almond leaves to the tank to soften the water and slightly lower pH.
Feeding Corydoras
Corydoras are omnivores that need a varied diet. Sinking pellets and wafers (Hikari Sinking Wafers, Sera Wels Catfish Chips) should form the base of their diet — these reach the bottom before surface fish can eat them. Feed small amounts twice daily: just enough that the corys finish everything within 5-10 minutes.
Supplement 3 times per week with: frozen or live bloodworms, frozen daphnia, frozen brine shrimp, or blanched zucchini/cucumber rounds. Corydoras are surprisingly active hunters of live or frozen food — they will chase bloodworms across the tank.
In Cambodia, fresh live blackworms are sometimes available from aquarium suppliers — Corydoras love them and they are one of the best conditioning foods for bringing Corydoras into breeding condition. Feed live blackworms sparingly (1-2 times per week maximum) as overfeeding live food can cause fatty liver disease.
Best Corydoras Species for Cambodia Aquariums
Corydoras sterbai: Top recommendation for Cambodia. Handles warm water to 30°C. Beautiful orange-and-white spotted pattern. Grows to 6cm. Available from quality fish suppliers. Cost: $3-6 per fish.
Corydoras aeneus (Bronze Cory): Most widely available, most affordable ($1-3 each). Tolerates a wider range of conditions than most. Plain bronze color, but active and social. A good "starter cory" for beginners.
Corydoras panda: Black-and-white panda markings make this species a showpiece. Prefers 22-26°C — challenging in Cambodia without cooling. Best for air-conditioned fish rooms. Cost: $3-5 per fish.
Corydoras habrosus / pygmaeus (Dwarf Corys): Tiny species (2-3cm) that swim in mid-water as well as on the bottom. Fascinating behavior but need larger groups (10+). Harder to find but worth seeking out for planted tanks.
At 4848 One Shop, we stock Corydoras sterbai and Corydoras aeneus year-round. Browse our catalog for current stock, or message us on Telegram for availability of rarer species.