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How Many Guppies In A 10 Gallon Tank

Starting a guppy tank is an exciting venture because there are so many different types of guppies to choose from that you are bound to be overwhelmed by their sheer beauty. However, you don’t want to overcrowd your new tank. How many guppies can fit in a 10-gallon tank?

The recommended amount of guppy fish to add to a 10-gallon fish tank is 5-10 adult guppies. That is after taking into consideration the filtration, substrate, and frequency of water changes. Here’s what you need to know.

Number of Guppies

Using the 1 inch of fish per 1 gallon of water rule is a safe starting point when introducing guppy fish to a tank. For example, a 10-gallon aquarium, despite the name, holds around 7-8 gallons of water. Adult guppies grow to about 1.5 inches in length (excluding the tail fin). Using the rule, that means that you can keep just about 7 adult guppies in a 10-gallon tank.

How to Add More Guppies to a Tank

Sometimes, you may want to add a bit more fish to your aquarium. You can do this but you have to ensure that there is proper filtration, live plants, good maintenance, and a feeding schedule.


Most starter kits include internal filters. However, if you plan to add more than the recommended number of guppies in the tank you need to buy a bigger internal filter.

An alternative is to buy an external canister filter or a filter that hangs onto the back of the tank. This way, it doesn’t take up space in the tank. Thus, you can add more fish. A good option is the Aqueon QuiteFlow 20 HOB. This filter is for a 20-gallon tank, ideally. But, it works just fine for overcrowded 10-gallon fish tanks. The SunSun HW-603B filter is another great option for tanks that have unremovable lids.

Aqueon QuietFlow LED PRO Aquarium Power Filters, Size 20-125GPH
  • Provides mechanical, chemical, biological filtration plus additional assistance with the Aqueon specialty filter pads
  • Self-priming – starts up automatically after cleaning or power interruptions.
  • Certified flow rates that assure proper water circulation for improved fish health
  • LED indicator light flashes when it’s time to replace clogged cartridges by monitoring actual water levels.
  • Internal pump design helps dampen noise and eliminate leaks
SunSun Tech'n'Toy HW-603B 106 GPH 3-Stage External Canister Filter
  • Good for up to 20 gallon fish tanks
  • Dimension: 6.5" L X 6.5" W X 11" H
  • Flow rate: 106 GPH (400L/hr.)
  • Pump Power: 6W
  • Includes filter pads, hoses and all parts to get started

Filter Media

A sponge-based filter media won’t work well for an overstocked tank. Adding a biological filter media along with a sponge filter is ideal. The latter will soak up most of the muck while the biological filter provides a large surface area for bacteria (the good kind) to decompose toxins. The Seachem Matrix and the Eheim Substrat Pro both have good reviews on Amazon.

Matrix, 2 L / 67.6 oz.
  • Supports Denitrifying Bacteria
  • Extreme Surface Area
  • No need to replace ever
EHEIM Substrat Pro Biological Filter Media (Sintered Pearl-Shaped Glass) 2L
  • Made of highly porous artifiical sintered glass material
  • Unbeatable surface area structure of 1800 sq ft per gallon
  • Can be reused by lightly rinsing with aquarium water every 1 to 3 months and replaced every 3 to 6 months
  • Provides longer intervals between required maintenance
  • For use in all EHEIM filters (Classic, Ecco, Pro 3, Pro 3e)

Live Plants

Live aquarium plants help get rid of the toxins produced by fish waste. Waste helps them grow. Fast-growing plants extract more nutrients from the water column. Plants also slow algae growth. Guppy grass, hornworts, and wisteria are good choices.

When you do add plants to the aquarium be sure that they get 6-8 hours of light. Without light, the plants die and pollute the water. Though not necessary, you can add an aquarium plant fertilizer to help plants grow.

Special Substrate

Instead of using gravel, there are other substrates such as  Seachem Flourite that promote the growth of beneficial bacteria which helps break down fish waste. If you do decide to use gravel (cheaper), you can use an aquarium gravel vacuum to clean the waste caught in the gravel.

Flourite Dark, 7 kg / 15.4 lbs
  • No laterite needed
  • Perfect for planted aquariums
  • May be mixed with other gravels
  • The Premium Substrate For the Planted Aquarium
TERA PUMP Genuine Aquarium Fish Tank Gravel Sand Cleaner Long Nozzle Water Changer Flow Controller BPA Free TRFTCLN
  • Model: TRFTCLN has a Large suction tube allows for use in bigger Aquariums ( 10 Gallons or Greater )
  • Discharge Hose Clip Included (2019 Updated) Simply Attach the Discharge Hose Clip to your container / Prevents hose from falling off container
  • Two Types of Nozzles: Shorter Nozzle is for Drainage & The Longer Nozzle is for Cleaning Fish Leftover Food, Droppings and Fine Gravel / Takes the Waste out while Replacing the Water; Will not Hurt any Aquarium Life when in use
  • Suction Cub: Securely keeps the suction tube in place allowing the pump to operated with one hand
  • Filter will keeps Large Gravel from entering pump to prevent blockage while operating ( 1.5 Gallons per Minute )

Feeding Schedule

Guppies don’t like to refuse food. They can be rather greedy. However, overfeeding can lead to diseases and parasites that affect your fish.

Feeding your adult guppies every other day is enough to keep them healthy and reduce water pollution. Add only a small pinch of food at a time. Wait for the fish to eat it all and add another small pinch of food. Do until you feel that they have had enough (varies depending on the number of fish in the tank).

Tank Maintenance

Keeping more than the recommended number of fish in a 10-gallon tank means that you need to change the water more often. With a good filter and filter media, you can get away with weekly water changes. A 30-50% water change is about right

Lastly, clean the filter regularly. Wash the filter media using aquarium water once every other week. Please don’t use tap water to wash the filter media as the chlorine in the tap water will kill all the good bacteria. Do not keep the biological media dry for extended periods of time as the good bacteria will die.


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