How to Remove Fish from an Aquarium to Clean

Clean the tank as quickly and as thoroughly as you can. Because the whole transferring process can be stressful to your fish, as can just being away from its normal habitat, try to work as quickly as you can to clean the tank. Plan out what you need to do beforehand and lay out the equipment you’ll need to use so everything is easily accessible.^[7]

• Never leave your fish in the temporary container overnight. Make sure you set aside enough time to completely clean the tank all at once so that they’re back at home within a few hours at the most.

Scrub the algae off the walls if it has become overgrown. Do this before removing any water. Sometimes the chemical balances in the water can make excessive algae grow and cover your tank, and it gets to be too much for your normal filtration system to handle. If this happens, use an algae scrubber to remove the visible sections of algae. You can also use your aquarium vacuum to siphon away any algae that is on the bottom of the tank.^[8]

• If some sections are really stuck on, use a razor blade to scrape it off. Just be very careful to not accidentally hurt yourself.

Change 20% to 25% of the water if the tank is excessively dirty. Normal tank maintenance has you replace 10% to 15% of the water on a weekly basis, but sometimes you might need to do a little more. For example, if your tank hasn’t been cleaned in several weeks, or if your fish have started to get sick or die, you might need to do a larger change than you normally would. Keep in mind:^[9]

• If you have a saltwater aquarium, you will need to check the saline, pH, and ammonia levels and get them back to a normal range before replacing your fish.
• If you have a freshwater aquarium, you will need to pay attention to the water temperature and dechlorinate the water before you add it to the tank.

Transfer the fish back to the aquarium once you’re done cleaning. Once the tank is clean, gently net the fish and put them back into the aquarium. Remember to move 1 fish at a time and to lower the net into the aquarium to safely release them.^[10]

• Don’t forget to feed your fish once they’re back home.

Change 10% to 15% of the tank’s water every week. Fill up a bucket (always use a clean bucket that has never been washed with chemicals or detergents) with tap water for a freshwater tank or reverse-osmosis water or distilled water for a saltwater tank. Check that the water temperature is the same as the water currently in the aquarium. For a freshwater tank, add in a de-chlorinator to treat the water. For a saltwater tank, treat the water with an aquarium-specific saline solution. Then use an automatic water changer to siphon off old water and replace it with the new water.^[11]

• If you don’t have an automatic water changer, you’ll need to haul off several buckets-full of water manually and replace them with the fresh water.
• Don’t just “top off” the tank to replace water that has evaporated. The water still has some built-up impurities that need to be replaced, and that’s only done by removing and replacing water.

Clean out the filters on a bi-weekly or monthly basis. Fill a small, clean bowl with water from the aquarium. Remove the filters and rinse them out in the bowl. Never use tap water, because that can remove the good bacteria that you need to keep your tank healthy. Replace the filters right away.^[12]

• If the tubing for the filters looks dirty, use a pipe cleaner or filter brush to scrub them clean, too.

Scrub away algae from the walls of the aquarium bi-weekly. Use an algae scrubber to scrape down the sides of the tank, working from the top of the tank down to the bottom. Make sure your hands are clean before you put them into the tank, or wear clean rubber gloves to do this work.^[13]

• Never use a dish sponge or rag to clean the tank. These could introduce harmful bacteria to your aquarium.
• If you don’t already, think about getting some algae-eating creatures to help keep your tank clean.

Siphon the gravel every 2 weeks to clean away waste. Use your aquarium vacuum by sticking one end into the gravel and following the manufacturer’s instructions. Vacuum the bottom of the tank back and forth until the water coming out the other end starts to run clear.^[14]

• You usually don’t need to clean all of the gravel. Rather, try cleaning just 1/4 to 1/2 of it. This will leave some of the healthy bacteria in place that helps keep your aquarium’s habitat running.