Corydoras Care Hub: Bottom-Dweller Basics and Group Needs

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Corydoras Care Hub: Bottom-Dweller Basics and Group Needs

Corydoras ("cories") are small, peaceful catfish that live on the bottom and must be kept in groups of at least six of the same species. Give them a soft sand substrate, sinking food that reaches the floor, a cycled tank around 22–26°C and clean, stable water. They are hardy and charming, but they are not tank cleaners , they need feeding like any other fish.

• Group size: minimum 6 of the same species.
• Adult size: about 4–7 cm depending on species.
• Substrate: fine, smooth sand , not sharp gravel.
• Temperature: roughly 22–26°C (some prefer cooler).
• They breathe air occasionally , a dash to the surface is normal.

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Substrate: why sand matters

Corydoras forage by sifting the substrate with delicate sensory barbels ("whiskers"). On sharp or dirty gravel, those barbels wear down and can become infected and eroded , a common, avoidable problem. Use fine, smooth sand or very rounded fine gravel, and keep it clean. Healthy cories will constantly "dig" and sift, which is exactly the behaviour you want to see.

Fine sand protects a cory's delicate barbels , sharp gravel can wear them down and cause infection.

Group needs

Cories are social shoaling fish. Kept singly or in pairs they become withdrawn and inactive; in a group of six or more of the same species they forage together, rest in piles and show real personality. Mixing several different cory species in small numbers is not the same , each species does best with its own kind, so build a proper group of one type where you can.

Corydoras are social , a group of six or more of the same species is far more confident and active.

Feeding a bottom-dweller

Because cories feed on the floor, food must actually reach them. In a busy community tank, fast mid-water fish often eat everything before it sinks. Use sinking pellets, wafers and tablets, plus frozen or live bloodworm, daphnia and brine shrimp. Feed after lights-out or in a quiet corner if faster fish outcompete them. Never assume they will "clean up" leftovers , that myth leaves cories slowly starving.

Water and tank mates

Keep ammonia and nitrite at 0 and nitrate low with weekly water changes. Cories prefer soft to moderate, neutral water and appreciate gentle flow and good oxygenation. They are perfect community fish with tetras, rasboras, guppies and dwarf shrimp. Avoid large or aggressive tank mates, and never keep them in tanks treated with copper-based or high-salt medications without checking , scaleless catfish are sensitive to some treatments.

Living context by region

This guide is written for multi-region English readers (US/UK/AU/NZ/CA/EU and more). Where climate, products, or vet access differ, prefer local veterinary advice and local product labels. Use metric first; keep °F/lb in mind for North American homes.

When to call your vet

• Signs are getting worse over hours, not better

• Pain, persistent vomiting/diarrhea, or neurological signs

• You needed force or guesswork to keep going at home

Common mistakes

• Waiting because the animal 'still looks okay' while prey species hide pain

• Changing five variables at once so you cannot tell what helped

• Copying drug doses from social media

• Skipping species-appropriate husbandry while buying more gadgets

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