Outdoor pond fish stocking depends on pond size + winter temperature. Pond essentials: 1,000+ gallons for koi (some varieties grow 24-36"), 200+ gallons for fancy goldfish, 50+ gallons for shubunkin/comet. Depth 4+ feet in cold climates to prevent freezing. Best beginner fish: shubunkin (calico goldfish variety, hardy, beautiful), sarasa comet (red + white, fast swimmer), common goldfish (most cold-tolerant), golden orfe (schooling, fast surface fish). Show koi: intermediate-advanced. Kohaku (red + white), sanke (red, white, black), showa (black, red, white), butterfly koi (long-finned). $50-50,000+ each. Native pond fish (US): rainbow shiner, native sunfish (in larger ponds), mosquitofish (controls insect larvae). NOT for ponds: tropical fish (die in winter), oscars (won't survive temps under 60°F), cichlids (most), bettas, large predators (bass) unless you want to lose your koi. Stocking density: 1 inch of fish per 10 gallons of pond water. Underestimate to leave room for growth. Predator-proofing: use heron-deterrent decoys + wire mesh on top. Raccoons + cats also threats.
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