Choosing the Right Pond Fish: Goldfish, Koi, and Compatibility Guide

What to Consider When Purchasing Fish

Start by knowing your pond's capacity. General rule: 1 inch of fish per 10 gallons of water. A 50-gallon pond supports one 6-in. fish, two 3-in., or six 1-in. fish. If unsure of volume, underestimate.

Check the shop's cleanliness—clean tanks indicate good care. Avoid tanks with dead fish; that signals disease. Watch for sick fish: isolation, clamped fins, missing scales, sores, or missing fins.

Common Types of Fish

Common goldfish, comets, fantails, orandas: All are goldfish varieties, can live 25 years if cared for. Common goldfish and comets have slender bodies, grow >12 in., are fast, hardy, and compatible with koi.

• Common goldfish: Hardiest, tolerates 35°F. Usually bright orange, also yellow, silver, brown, or mixed.
• Comets: Least expensive, nearly as hardy. Longer, thinner, longer tails. Colors: gold, orange, brown, blue, red/white, orange/white, orange/black, calico (Shubunkins).
• Fantails & orandas: Fancy goldfish with rounded bodies and fan-like tails. Grow ~5 in., larger with space. Don't mix with faster, aggressive fish. Tolerate 45–90°F. Fantails in many colors. Orandas often orange/red with white; develop a red/orange "cap" on head at adulthood.

• Japanese koi: Carp family, popular pond fish. Colors: red, orange, yellow, black, blue, cream. Bright colors attract predators (herons, raccoons)—need defenses. Hand-feedable, personable. Cold-water fish, grow to 2 ft, live 30 years. Voracious eaters—may devour plants in small water gardens.