Health How long can goldfish live in 10-gallon tank? How long can goldfish live in 10-gallon tank? Imagine being a single goldfish living for years in an empty bowl with nothing to do. Other experts say a 10-gallon tank is too small for even one adult goldfish, which can live an average of 25 to 30 years.18 Jan 2022 Related Posts:Can a small goldfish live in a 5 gallon tank?Take care of Goldfish.Goldfish should be taken care of.How To Goldfish should be taken care of.