Goldfish are easy to raise in both aquariums and outdoor ponds due to their tolerance for a wide range of temperatures and water conditions. While goldfish are best suited to share a tank with members of their own species, it is possible to let them share space with a few species of catfish that won't grow large enough to harm the goldfish.
When considering putting a catfish in with your goldfish, both species should top out at about the same size. While goldfish can reach 10 to 18 inches long, some species of catfish can grow to several feet long, large enough to devour even a large goldfish. Corydoras catfish mature at less than 4 inches long, making them potential tank mates for smaller species of fancy goldfish. Synodontis catfish top out at 8 inches, making them potential aquarium mates for larger common and comet goldfish.
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