Corydoras catfish are social shoalers that require companions of their own species. Absolute minimum: 6 of the same species (not "6 mixed cories"). Mixed-species groups don't shoal - each species needs its own 6+. Ideal numbers: 8-10+ for active foraging behavior, courtship displays, and breeding. Tank requirements: minimum 20-gallon long for the smaller species (pygmaeus, habrosus, hastatus). 29-gallon+ for medium species (panda, sterbai, julii, trilineatus). 40-gallon breeder for the bronze + emerald cories (paleatus, aeneus). Substrate: sand or smooth fine gravel ONLY. Sharp gravel destroys their barbels (sensory whiskers). Once damaged, barbels rarely regrow. Tankmates: peaceful community fish - tetras, rasboras, dwarf gouramis, livebearers. AVOID with: angelfish (eat juvenile cories), oscars + larger cichlids, aggressive plecos. Diet: not just bottom-feeders eating leftovers. Need dedicated sinking pellets (Hikari Sinking Wafers, Repashy Bottom Scratcher) + occasional bloodworms or live blackworms. Group dynamics: solo cory = stressed, hiding, dim color. Add 5-6 more and watch the entire personality change overnight.
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