Keep in mind this is a general guideline and isn’t set in stone. Keeping more than five guppies in a ten gallon tank won’t hurt them, but you’ll have to put a little more effort into tank maintenance.

Choose a filter that’s powerful enough for your tank size. It should filter your water at least five times per hour, so if you have a 10 gallon tank, you’d want a filter that circulates 50 gallons per hour. Undergravel filters require a little more maintenance, as you’ll need to vacuum clean the gravel frequently.

Don’t use gravel or sand from your backyard or other outdoor spot. You could risk introducing harmful bacteria and parasites to the habitat. If you plan on adding live plants, check the label before purchasing gravel to make sure it can support plant life.

Make sure rocks and other decorations are firmly set in the gravel. You won’t want them to fall over and hurt your fish in the future.

Without an eight hour dark period, guppies can’t rest properly. Without enough light, they’re prone to developing deformities.

You can find a dechlorinator at the pet store. Typically, you’ll add a drop or two of dechlorinator per gallon of water, but check your product’s label for specific instructions.

Continue to test the water every other day and add more ammonia if necessary. After a week, start testing for nitrites, which will indicate bacteria are starting to grow and consume the ammonia. Within a few more days, you should see ammonia and nitrite levels drop, and nitrate levels rise and plateau. At this stage, you’ve completed your first nitrogen cycle. It’s best to do a fishless cycle so that no fish have to suffer through ammonia exposure.

Gradually equalizing will help your fish adapt to their new home.

Avoid letting water from the bag into the tank. You could risk introducing unwanted contaminants from the pet store. Lift the bag out of the tank, open it, and use a scoop or cup to remove water without spilling. Then tie or seal it securely.

If you use a bucket or quarantine tank, use the same procedure as floating the bag in your aquarium tank. Replace a cup of water every ten minutes for an hour.

Don’t pour the fish into tank, as you’ll get water from the bag into the tank along with the fish.