The short answer
Sources here split care by interval. Daily: feed small amounts and check the fish, temperature and equipment. Every week or two: wipe algae and siphon out part of the water. Most put filter care at about monthly; testing runs weekly to monthly, by source. Unplug appliances before your hands go in; plug back in afterwards, in the order below.
This routine is for a freshwater tank already set up and cycled. Each maintenance task links to our guide with the full steps and cautions. Saltwater tanks add jobs: one author’s marine checklist in Tropical Fish Hobbyist Magazine adds a daily check of “water temperature and specific gravity”.
Before your hands go in the water
Fluval, an aquarium equipment maker, in its AquaClear filter manual: “Always unplug or disconnect all appliances in the aquarium from electricity supply before placing hands in water, before putting on or taking off parts and while the equipment is being installed, maintained or handled.” Aquarium Co-Op, an aquarium retailer, on draining: “Aquarium heaters and filters are not meant to operate without water and therefore can become damaged when running in dry air.”
Heater waits before water comes out differ. Fluval’s E heater manual: “wait for at least 30 minutes to allow it to cool down”. Hydor, a heater maker, in its Theo manual: “To avoid possible breakages due to thermal shock”, “at least 5 minutes” (its support page: at least 30). Follow your heater’s manual; with none, our reading is the longer wait.
Plugging back in. Aqueon, an aquarium equipment maker, reinstalls the filter in its cleaning checklist “but do not plug back in yet”, refills, then: “Plug the filter and heater back in.” Hydor’s support page says its heater can be “turned back on when the Aquarium is full and the heater is completely submerged”, and only then. A heater that came out of the water gets its manual’s wait: Hydor’s Theo manual, “After immersing it in the water, wait a few minutes before switching it on”; Fluval’s E manual, “Allow heater to acclimatize in the aquarium water temperature for 20 minutes before plugging it into the electrical outlet.” For a power filter, Fluval’s AquaClear manual: “First, ensure the filter case is completely filled with water”, and “Follow operating instructions to restart and prime power filter.” For a quick job with no water change, the plug-back point is our own wording: once your hands are out.
The CDC, a US federal health agency: “Wear gloves when cleaning or caring for your aquarium, especially if you have cuts or wounds on your hands or if you plan to work with rough rocks or spiny fish.” Also: “People with weakened immune systems should let others in the household care for the fish tank when possible. If this isn’t possible, they should wear gloves.” and “Don’t let children younger than 5 years old clean or handle aquarium items.” It says to wash your hands “with soap and running water”, including “After cleaning your pet’s tank”. Also: “Dump tank water and clean aquarium items in a bathtub, laundry sink, or outside instead of a kitchen sink when possible.” and “Clean and disinfect sinks and bathtubs after using them to dump aquarium water or clean aquarium items.” For cleaning tools, Aqueon: “Don’t use buckets, scrub pads or any other equipment on your aquarium that have been used with soap or other chemicals.”
Daily: feeding and a quick look
- Feed small amounts. PetMD, a Chewy-owned pet-health site: “Fish should typically be fed once or twice daily in small amounts they can consume within a few minutes.” It adds: “Feeding requirements can vary by species.” Aqueon gives a different time: “Don’t feed more than your fish can consume in under 2 minutes. Uneaten food can pollute the water and stress your fish.” Dr. Jessie Sanders, an aquatic veterinarian, lists “Remove excess food” daily. If your hands go in, unplug first (Fluval, above); plugging back in once they are out is our own call.
- Look at the fish. Dr. Sanders: “Evaluate fish swimming behavior and appetite (make note if anything seems different)”. If something seems off, see below.
- Check the temperature and equipment. API, a water-care and test-kit maker: “A quick inspection of the heater temperature and filter function is good to keep an eye on.” Our guide to what temperature a fish tank should be lists ranges by fish type. For aeration, see increasing oxygen in a fish tank, with or without an air pump.
- Top off. Dr. Sanders: “Monitor water level and top off if necessary”. Aqueon: “Always treat tap water with a water conditioner to neutralize chlorine and ammonia before adding it to the aquarium.”
Every week or two: algae, gravel and part of the water
Unplug first, as above. The Spruce Pets, a pet-care publisher, saves the water change for last: “Leave the partial water change as the last task.”
- Algae. Dr. Sanders’s weekly list: “Scrub algae from sides of aquarium”. Our guide to getting rid of algae covers scrapers for glass and acrylic, and prevention. Unplug first; on a day with no water change, plug back in once your hands are out (our wording, first section).
- Gravel or sand. Timing differs. The Spruce Pets siphons the substrate “every week or two”; PetSmart, a pet retailer: “Gravel vacuum at least once per month.” Dr. Sanders’s weekly change uses a gravel siphon, and her monthly list adds “Vacuum gravel under décor”. Our guides to cleaning fish tank gravel and cleaning aquarium sand give the steps.
- Part of the water. Before water comes out, unplug and give the heater its manual’s wait; heaters and filters can be damaged running dry (Co-Op; both in the first section). Treat the new water; Aqueon: “Replacement water should be the same temperature as the aquarium water.” PetSmart: “Do not remove fish for routine tank maintenance.” Aqueon: “Don’t completely tear down your aquarium to clean it. This will destroy the biological balance with disastrous results.” Plug back in only once the tank is refilled and the heater fully under water; a heater that was out of the water gets its manual’s wait first (first section); fill and prime a power filter per its manual (above).
Our water change guide has the steps, and cleaning a fish tank puts a whole session in order. For one betta, see cleaning a betta fish tank.
Water change percentage and frequency, by source:
| Source (type) | How much | How often |
|---|---|---|
| Aqueon do’s and don’ts (maker) | 10%, or 25% | Weekly, or every two weeks |
| Aqueon cleaning checklist (maker) | At least 25% | Each full clean; no interval |
| API routine care (maker) | 10-30% | In its weekly/biweekly tasks |
| Dr. Sanders’s checklist (aquatic vet) | 10%, or 25% | Weekly, or every other week |
| PetMD (pet-health site) | 10–25% | Weekly |
| PetSmart (retailer) | 10-50%; “In general, a safe range is 20-30% weekly.” | Typically every 1-2 weeks |
| Fishkeeper UK (retailer) | 25%; “can be tailored to your stocking levels and feeding rates” | Weekly |
Dr. Sanders calls her figures “only a general guideline”, and PetMD says “Frequency may vary based on tank size and fish load.” Three sources set a ceiling (the most in one change, not a target), and they conflict. Aqueon: “Avoid water changes of more than 25% as larger water changes can stress your fish and upset the balance in your aquarium.” API: “It is not recommended to do more than 30% because it may cause loss of bacteria and be stressful on the fish.” PetSmart: “Avoid replacing more than 50% of aquarium water at a time.” So PetSmart allows up to 50% where Aqueon and API stop at 25% and 30%. Aqueon’s own two pages also differ: its checklist says “at least 25%”, its do’s and don’ts avoid more than 25%. We give no figure of our own.
Weekly to monthly: test the water and look after the filter
- Test the water. Timing differs. API: “Test the aquarium water weekly-biweekly to be aware of what could be happening biologically in the tank is important.” The Spruce Pets: “Water testing should be performed monthly to ensure nothing unseen is brewing.” It lists “pH, ammonia, nitrite, and nitrate”. Dr. Sanders’s checklist tests weekly when new fish or equipment went in “within last 2 months”, and monthly otherwise. Unplug first if your hand goes in for the sample, and plug back in once it is out (our wording, above). For off readings, see our guides to lowering ammonia, nitrite and nitrate, and to lowering or raising pH.
- Look after the filter. Most sources here say about monthly. Aqueon: “Change filter cartridges at least once a month. Check them weekly and rinse as needed.” API: “Change out the filter cartridge every 4-6 weeks on different days from doing a water exchange.” PetSmart: “Filter cleaning should be done approximately once per month, but not during the gravel cleaning as too much beneficial bacteria can be lost at once.” PetSmart says biological filter media “should never be cleaned in tap water and should not be allowed to dry out”, and The Spruce Pets: “However, avoid replacing all the filter media at the same time.” Aqueon’s checklist cleans the filter in the same session as the water change. Unplug first; to restart, fill and prime a power filter per its manual (above). Our filter cleaning guide covers sponge, hang-on-back and canister filters.
- Once a year. Dr. Sanders’s checklist: “Buy new water test kit”.
Our freshwater test kit roundup includes the API master kit below; our water conditioner roundup includes Seachem Prime.
| # | Preview | Product | Price | Link |
|---|---|---|---|---|
| 1 |  | API Freshwater Master Test Kit 800-Test Freshwater Aquarium…Liquid test kit | Check on Amazon | |
| 2 |  | Seachem Prime -500 ml/ 17 fl. oz. | Chemical Remover and…Water conditioner | $16.62 Prime | Check on Amazon |
When you add fish
Dr. Sanders’s checklist tests weekly for two months after new fish; her resolutions page: “Quarantine any and all new fish and plant additions to your system to prevent the spread of disease.” Aqueon: “Test the aquarium water for pH, ammonia and nitrite before adding new fish.” See our guides to quarantining and adding new fish.
If a fish looks sick
We give no diagnosis or treatment. Test the water (guides above) and contact an aquatic veterinarian. PetSmart points owners to the Find a Fish Vet tool at fishvets.org or wavma.org. Dr. Sanders, on your fish vet’s number: “Write it down and post it next to your tank or pond, just in case.”
Aquarium care don’ts
Each sits with its source above: hands in only when unplugged, power back in the order given; no soap-used tools; no overfeeding; treated water only; no full teardown; no tap water on biological media, nor all of it replaced at once.
Your equipment’s manual comes first
Where your equipment’s manual differs from these schedules, follow it. Dr. Sanders’s checklist: “Cleaning frequency and volume will be determined by bioload, size of tank and filtration capability.”
Ready to buy?
Our water conditioner roundup compares conditioners, and our Tank Setup & Care section has more routine guides.
Frequently Asked Questions
Q. Are aquariums easy to take care of?
PetMD: “Fish are not low-maintenance pets because they require regular care, clean water, and proper habitat setup.”
Q. How long do you need to leave a tank before you put fish in it?
Sources give two different waits. Aqueon’s do’s and don’ts: “Let a newly set up aquarium run for 2 to 3 days before purchasing your first fish.” In a new tank, these sources give weeks for the bacteria to build, not days. Aqueon, with fish added to a new freshwater tank: the whole process “typically takes three to eight weeks”. API, which starts with a few fish: it “can take between 2-6 weeks”. UF/IFAS, in a university aquaculture publication: a new biofilter “requires six to eight weeks”. Fishless methods and bacteria products differ; our guide to cycling a fish tank sets out each method.
Q. Can I leave my aquarium for 2 weeks?
Sources differ, on food only. PetMD: “Some species, such as goldfish, may survive up to two weeks without food, though this should not become a routine practice.” Aqueon: “Herbivores, small active fish, and baby fish, on the other hand, need to eat every day or two.” For a weekend, it says: “Virtually all fish — short of newly hatched fry (aka, baby fish) — can go that long without being fed.” Aquarium Co-Op, for healthy fish: “If you’re only leaving for a week or less, the easiest method is to not feed your fish.” Our vacation feeding guide covers four ways to feed fish while away.
Q. How do you take care of a fish in a bowl?
Dr. Sanders, on her betta page: “No fish should live in a bowl.” Our betta tank cleaning guide covers small unfiltered containers.
Sources (22)
- Fluval, AquaClear manual (maker)
- Fluval, E heater manual (maker)
- Hydor, Theo manual (maker; linked from hydor.com/products/theo)
- Hydor, support page (maker)
- Aqueon, Do’s and Don’ts (maker)
- Aqueon, Aquarium Cleaning Checklist (maker)
- Aqueon, The Nitrogen Cycle (maker)
- Aqueon, traveling prep (maker)
- API, How to Cycle a New Tank (maker)
- UF/IFAS, FA031 (university extension)
- API, Routine Aquarium Care (maker)
- Dr. Jessie Sanders, Fish Tank Cleaning Checklist (aquatic vet)
- Dr. Jessie Sanders, New Year’s Resolutions for Fish Owners (aquatic vet)
- Dr. Jessie Sanders, betta care (aquatic vet)
- PetMD, How To Take Care of Fish (pet-health site; PetMD by Chewy)
- PetSmart, Aquarium Maintenance Guide (retailer)
- The Spruce Pets, Routine Aquarium Maintenance (publisher)
- Aquarium Co-Op, How to Properly Clean Your Fish Tank (retailer)
- Aquarium Co-Op, fish on vacation (retailer)
- Fishkeeper UK, water changes and filters (retailer)
- Tropical Fish Hobbyist Magazine, marine maintenance checklist (magazine)
- CDC, Healthy Pets: Fish (agency)
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