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First time setting up a 55-gallon freshwater tank, how many fish?

Updated On September 23rd, 2025

Pet's info: Fish | Unknown - Fish

setting up my first ever freshwater fish tank, need to know how many fish should I put in my 55 gallon fish tank,

2 Answers

Most Helpful Answer

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Answered By Angel Alvarado, LVT

Licensed Veterinary Technician

Published on October 30th, 2017

For small bodied fish (tetras, minnows, guppies, etc) the general "one inch of fish per gallon" rule will likely be fine. For larger bodied fish (goldfish, plecos, Oscars, etc), it should be closer to one inch of fish per 3 gallons of water. Always use the full grown adult size when deciding how many fish to keep. Take into account schooling fish as well which should be kept on groups of at least 5-6 fish.

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    Answered By Linda G, MS, DVM

    Veterinarian

    Published on

    Hello, & thank you for using Petco Pet Education Center, formerly Petcoach. The general rule of thumb is 1 inch of fish per gallon of water. Do not forget to include rate of potential growth of the fish you choose. In other words, calculate for the adult or full growth of the fish you plan to add. Have fun!

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