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Ask Martha: Advice for First-Time Fish Owners

I’m a first-time fish owner. Any tips for tank setup?
—Kimber Rutledge, Saint Charles, Mo.

Photography by: Yoko Inoue

Arranging your tank properly ensures that your pet has a smooth transition to its new home. Follow these steps from Stephen Zawistowski, science advisor emeritus for the ASPCA:


  1. Buy a 20-gallon tank. Not only will your fish have plenty of room to swim, but it’s easier to maintain healthy water conditions in a larger aquarium.
  2. Fish like to hide and have a place to relax. Use plastic plants or other tank décor, such as a treasure chest, to add camouflage.
  3. You’ll need a filtration system to keep the water fresh and eliminate waste. Choose either an easy-to-clean filter that hangs on the tank’s side or an invisible version that hides under the gravel (but is admittedly a little more trouble to clean).
  4. Fill the tank to one inch below the rim with tap water (65 degrees for goldfish; 78 for tropical fish). Most fish thrive in water with a pH of about seven—neither acidic nor alkaline— so test the pH with a kit and use a chemical neutralizer to adjust the level. (Both are available at pet stores.) Then let the water sit for a few days before introducing your new pet.