Clear cloudy aquarium water, remove nitrates and simplify aquarium maintenance
Neon tetras in clear water freshwater aquarium

Aquarium maintenance tips and fish care guidelines

Good aquarium maintenance practices will lead to a healthy aquatic environment and thriving fish, providing years of joy for the hobbyist.

Jump to routine maintenance guide!

Expensive and time-consuming problems can be prevented by spending thirty minutes on maintenance every other week.

The biggest factor for maintenance is tank stability. As long as everything is running properly and your fish are healthy, there is no need for any major change, even if the pH or hardness seems to be slightly out of range; only increases or decreases of the major aquarium water parameters will need your careful but immediate attention.

Water Changes

A key part of aquarium maintenance is the water change, which should be performed about every two weeks. In most cases, 10-15% of the tank volume is sufficient. A good method is to replace the water extracted while vacuuming the gravel, which will eliminate uneaten foods and other residues that settle on the substrate.

It is highly recommended to check the water parameters of both the tank and replacement water. Most tap water (city water) contains either chlorine or chloramine. Chlorine will air out rather quickly (kept in an aerated bucked for twenty-four hours); chloramine (chloramine = chlorine + ammonia) will not. Using a water conditioner will neutralize the chlorine in both cases, but ammonia will still be present in the latter. It has to be broken down by the nitrifying bacteria present in the aquarium. This may take longer than your fish can tolerate.

Other elements of municipal water may be phosphates, iron, and other heavy metals. To find out about your tap water chemistry, call your local water company.

Well water is usually harder than tap water, but is chlorine/chloramine free.

Filtered water should also be checked on a regular basis and should be considered part of your aquarium maintenance routine. The filter membranes could be damaged or may require replacement prior to the expiration date.

Testing Aquarium Water

Water chemistry is not visible; therefore, it is vital to check it on a regular basis. The best way to make this a routine is to check on the tank chemistry while changing the water.

The vital parameters are pH, nitrates, nitrites, and carbonate hardness (salinity for marine tanks).

Stability is the main factor with pH. pH in the range of 6.5 – 7.5 is suitable for most species, but they can adjust if slightly out of range.

KH (carbonate hardness) is the indicator of pH stability. It should be kept under close observation if it comes close to 4.5 dH (degree hardness) or 80 ppm. You must take action if it decreases any further.

Half a teaspoon of baking soda per twenty-five gallons of water will raise the kH by about 1 dH (17.8 ppm).

Nitrites should be undetectable at all times (except during cycling). If you detect nitrites make sure you check on ammonia as well.

Nitrates should be kept below 10 ppm in freshwater and 5 ppm in marine and reef (preferably 0 ppm).

Aquarium Filtration

The proper function of the filter is essential. Filter inserts (floss, Algone, activated carbon) should be changed at least every four weeks. A high fish load may require shorter periods. Trapped particles will decompose in the filter as they would in the tank. The filter should also be cleaned once a month (do not touch the bio-wheels, if present) by using the water extracted from the tank during the water change.

Recommended Aquarium Maintenance Routine


  • Make sure the equipment is running properly.
  • Watch your fish during feeding. Behavioral changes are a good indicator of a potential problem.


  • Count your fish. In case of fish death, smaller species can decompose quickly, resulting in ammonia and nitrite spikes, and eventually high nitrate levels.

Every Other Week

  • Test your water for the vital parameters: pH, carbonate hardness, nitrite and nitrate.
  • Change 10-15% of the water .
  • Vacuum the gravel .
  • Clean the aquarium walls. Filter floss is fairly cheap and very efficient. Start from the bottom upward and rinse out often.
  • Rinse filter inserts (cartridges) with the extracted water.


  • Replace filter inserts, cartridges, floss, carbon, and Algone.
  • Inspect tubing, connections, airstones, skimmers and other parts for proper operation.
  • Clean aquarium top to assure your lighting is not affected.
  • Check the expiration dates printed on the boxes and bottles of the aquarium supplies you use. Do not use after the imprinted date. Expired test kits will give false readings and may prompt you to take unnecessary action.

52 thoughts on “Aquarium maintenance tips and fish care guidelines

  1. Hello..have read the above problems and their solutions. ..its really helpful..
    I have 4 gourami’s, one crocodile fish and recently bought 2 small goldfish…i have this aquarium for nearly more than 2 yrs…but previously my fishes had i had bought a new bigger aqurium 1 yr ago…my fishes almost all the time stay floating on the surface of water…plz suggest me something and previously my fishes would grow very big and it uses to be healthier fishes. .but after i have bought the bigger aquarium my fishes doesn’t grow like previously it used to be and my gold fishes are also not so much healthy…plz help me…plz suggest something. .☺☺☺

    • Priyanshu,

      I think you should take a look at your water parameters. Especially ammonia/ nitrate, pH and carbonate hardness (kH). If the parameters are not within the specifications fish will be effected adversely. More tolerant but not quite ideal parameters cause stress, which can lead to stunned growth. It also weakens the immune system making fish vulnerable toward diseases.

  2. Hi Scott,
    I have recently bought an aquarium having 2 angelfish, 2 red caps, 1 silver shark. One of the two angelfish frequently attack other fishes and bite their tails. What should I do to prevent it?

    • There isn’t much you can do about it. Best practice is to research fish compatibility before buying any. If a situation arises you should assure that you provide plenty of hiding spaces for different species of fish. Also, if possible you can try feeding several small portions a day. Be sure to spread the food and not to spot feed. Take care not to overfeed however, as this will only lead to water quality issues later on. As a last resort, you should consider the size of the aquarium and determine if it is large enough to provide enough space for all your fish. I hope this helps. I know how frustrating it is to watch a helpless fish constantly constantly get nipped by others.

  3. Hello Scott,
    Can you please suggest how many times I should feed them in a day. And can I give them natural foods like bits of leaves or cooked rice or something else. I would like to know what natural food I can give them.

    • We recommend feeding fish only once daily and sparingly at that. Fish are natural grazers but we tend to feed them to benefit our schedule and because we want to interact with our fish. Overfeeding inevitably results in increased water pollution which will degrade the quality of the aquarium and the health of the fish.

      You can certainly feed lettuce or other leafy vegetables to your fish. Vegetable clips are widely available at pet stores and can be used to conveniently place lettuce, etc inside the tank by attaching it to the glass via a suction cup. I don’t think rice is a good choice however. It’s purely a carbohydrate and lacks vital nutrition fish require.

      The healthiest food choices are live foods. A quick google search should return a lot of results regarding live fish foods. It would be far too much for me to get into here in the comments, but google should put you on the right track.

  4. I have a 75 g gall under both glass hoods is covered with algae , best way to clean it and keep it from coming back . Also in corners, any tricks for this ? My help has left me?

    • Hi Jenn, the best way to clean hoods is to take them off and scrub them in the sink. Careful if you use any soap, if you do, make sure you rinse the lids thoroughly because you don’t want any detergents in the tank as they will kill beneficial bacteria. It’s best just to use water and a scrub pad to clean them. Keeping the algae from coming back can be as simple as reducing water splashes at the tank’s surface. This is what causes the lid to become wet and eventually algae to take hold. Surface splash can be reduced by either assuring that you keep the water topped off or by lowering the filter’s return so it is stays submerged in the water.
      For the corners I would recommend this.

  5. Hello,
    My name is Owais and I’m new to fishkeeping. I have bought a medium sized aquarium (18″ * 12″ * 12″). The local vendor gave me 5 fishes. I don’t know what breed they are. Two of them are orange, one is orange and white, another is silver and a black one. I have a filter, air pump and a heater. It’s the first day for the fish in the aquarium but I noticed that they are confined mostly around the heater. The black one just lying just below the heater. Other 4 also don’t roam much. I have not fed them today as suggested by the vendor. Also they are mostly near the gravel and don’t come to the middle or the top portion.

    Can you please suggest.

    • Hello, some fish will prefer the top, middle or bottom of the aquarium. This varies depending on the species. Also, there are many fish that prefer to hide within the tanks ornaments and decorations. Again, this depends of the specific species. You could take pictures of your fish and visit your local aquarium store. They should be able to help identify the species you have and can also recommend other compatible fish that will compliment your fish tank.
      Also be sure to give the fish some time to acclimate to their new surroundings and you may very well find that they become less shy with time. Especially when they begin to associate your movement near the aquarium with feeding.

  6. Hi, I’ve a 20g aquarium with tropical small fishes, I have them for just about 2mos. I just noticed recently that some of the fishes have shiny spots like a grain of salt in them and one has ragged tail fin. Are these signs of diseases? What should I do or what does my
    aquarium need?

  7. I have 2 angel fishes, 2 gold and 2 white fishes…. I bought them yesterday. My tank capacity is 1*1*1.5 i have 6 medium sized and 3 small fishes. I added water to the aquarium (tap water) and then added fishes after 2 hours. Till now no deaths but i feel i see a little redness in the gold and white fishes after i turn on my filter. Also the angel fish looks too shy and lazy… It takes less or no food or very late. It also seldom visits upper part of water. It looks ok but i feel a hunch something is wrong. Please help.

    • It sounds too soon to diagnose any problems in your fish tank. Redness may be an inflammation of the gills due to ammonia and nitrite which will be present at some point during the first few weeks of a new aquarium. Once the aquarium has cycled, ammonia and nitrite should always be undetectable and therefore shouldn’t present a problem for your fish.

      Further, Angelfish are well known to be docile and will seek out hiding spots in the aquarium. They are not an overly active species. You should always provide ample plants (real or artificial) for them to hide in.

      Here are some links with valuable information concerning the setup of a new aquarium:

      The Aquarium Nitrogen Cycle
      New Tank Syndrome
      Feeding Aquarium Fish
      Aquarium Fish Stress

  8. Hi Scott – i have bought an aquarium 2 days back. its a 250Lt., 1.2Mt long aquarium with 16 fishes including catfishes, eel, goldfish, suckers etc. the first night i fed them at 11PM. next day, the fishes count at around 4 PM had become 15 and one catfish had a bulging stomach with a goldfish tail sticking out. my guess is it was eaten by the catfish. how can i prevent future cases like this? what is the ideal feed to fishes per day? twice? thanks.

    • Hello Rohan, I don’t know if there’s a foolproof formula to avoid larger fish going after smaller ones. While feeding may help, it is best to stick to non-egressive species (herbivores). You may also want to keep to fish that do not vary greatly in size.
      Our feeding guideline is usually only once per day and sparingly at that. The problem with feeding fish is over-feeding fish. Since an aquarium is a closed-loop ecosystem, great care needs to be taken not to pollute the aquatic environment. While a generous feeding schedule of ample food may prevent what you’ve experienced, the resulting waste accumulating will cause the water quality to quickly deteriorate. Harsh water conditions, cloudy green water and excessive algae growth are conditions caused by accumulating waste.

      Try feeding twice a day, morning and evenings, but only a pinch. Please do not use the guidelines provided by most fish foods that state to feed an amount the fish can eat in 3 – 5 minutes. That is far too much food and will spell doom for water conditions in the long run.
      Also provide good cover and hiding places for your more timid fish.

  9. I just got two of my first ever fish today and they seem very happy in their 20 gallon tank I have fake plants and a couple of structures with rocks at the bottom and the bigger one is eatin all the food, the behavior of the smaller one seems like it backs off when it comes to eating time what should I do?

    • This does not sound like unusual behavior. Some fish will hide when people approach the tank. It could also be attributed to territorial behavior of the other fish. This too is a normal situation in a fish tank. To make sure all fish eat in this case, avoid spot feeding. A pinch here and there at different locations of the aquarium’s surface will assure all fish have an opportunity to eat.

  10. is it good to turn off the air pump every night and turn it on in the morning? or should I keep it running 24hrs

    • An air pump is generally not a required piece of equipment. Oxygen primarily enters the aquarium through surface agitation. Most filter’s returns create enough surface movement to adequately oxygenate the fish tank. So to answer your question, provided there is constant surface movement in your aquarium, there is no need for an air pump at all hence turning it on and off at set times will not have an impact on your fish.

      Check our ‘Oxygen in the Aquarium‘ article for more information.

    • Distilled water is generally ok to use in aquariums but why take the risk of contamination by using water from a dehumidifier? Personally I would pass on trying this.

  11. I have a tank 5 * 2 * 2 ft size. What will be the water volume it holds in liters as well as gallons? I use ground water. There are 20 fishes which includes pirhana, parrot, sharrk, tin, cat fish, oscar, sucker-punch. I use external filter, oxygen motor & a heater. I feed them twice a day, only pellets, which they finish it within 2 min. The problem is water looks dirty very soon within 3-4 days from the time replacing of water & cleaning the filter. I found it too difficult to clean through the gravels & therefore i removed them. Replacing 20% of water doesn’t make much difference. So I have to change 90% of water every fortnight & that too becomes dirty within 4 days. Moreover, most of the fishes specially sharks gills becomes red & color goes pale. Adding medicine gives temporary result. Kindly guide me how to look after my fish.

    • The water volume would be 150 US Gallons or 566 Liter and from your description your tank is either overstocked, overfed, or still within the initial cycling period. Red inflamed gills are a sign of ammonia, which would support the notion of a disturbance within the beneficial bacteria. This can be due to a new tank, or significant changes that influenced the colony. Adding fish, medication, overfeeding can disturb the colonies.

      To start, the feeding should be reduced to whatever the fish can eat within one minute per day (rule of thumb). You can feed every other day to help reduce the waste and until the bacteria can catch up. The filtration, you can use filter material (polyester fibers) which will help to remove particles and waste at a higher. Replace the fibers often. Test your aquarium and the ground water. Make sure pH nitrates and kH are within parameters and ammonia is undetectable.

      We can’t of course summarize fish keeping in a few sentences, but please feel invited to browse our site for helpful information. You can email us directly for any assistance we can provide.

  12. Thank you. Your guidance was useful. I have got a pack of Algone. By mistake, I have got the pack for tanks of 110 gallons and above while my tank is actually about 10 gallons. I kept a pouch for a day and found the water not fully clear. Will this be a problem ? Can I continue to use this pouch ?

  13. Our goldfish have been getting white fungus which started with the tail and then spread to the rest of the body. Anti fungal drops helped temporarily but the fish eventually died ? The water had been changed completely once in 3 weeks. What could be the reason for the fungus ?

    • A good place to start would be here:

      Generally fish are more receptive to disease when they are stressed. Stress can be caused by imbalances in the water and poor water quality.
      While a complete water change may be done with good intentions and is likely more harmful because a big change like this will cause a lot of stress on your fish.

      Introducing new fish to the tank may also introduce bacterial or viral fish diseases. Some diseases may lay “dormant” until fish are susceptible because of increased environmental stress caused by water conditions.

      Bottom-line, it is vital to keep the aquarium balanced. Small incremental changes are recommended even when adjusting big imbalances.

  14. My betta fish’s bowl is unhealthy and needs to be transferred to the new bowl I’ve got as soon as possible. It’s been about 2 hours now that I’ve used chlorine tablet in the new bowl to remove chlorine from water and I’m beginning to get worried about my betta’s health he needs to be transferred to the new bowl. Is it safe to transfer him to the new bowl if just chlorine treated with tablet 2 hours ago

    • It should state on the directions of the product how long treatment takes. Liquid products usually work instantly and I believe the tablets work quickly after they dissolve. To be safe you should consult the directions or call the manufacturer of the tablets.

  15. sir
    i had 25 fishes before a day .yesterday i changed there water and after that my twelve fishes died till now.
    pls suggest how to change water plus proprply care them also at what temperature i have to put there heater on and for how much tim i have 3 feet long aquarium .

    • You should always make small, incremental changes to your aquarium. Large water changes can disturb the balance of the eco system by removing too many beneficial bacteria need to break down waste in the tank. This can lead to a disruption of the nitrogen cycle, requiring the aquarium to “restart” the process. During this time ammonia spikes are to be expected. Ammonia is lethal to fish as it severely inflames their gills and makes it difficult to breath. Bottom-line is that you should stick to 10 – 15% water changes no more frequent then once-a-week.

      The heater for a tropical fish tank should be set between 76 – 80 degrees F. Please check first however what temperature is required for your specific species.

      We recommend lighting only for about 4 hours a day. Light at a time when you will be spending time in the room so you can enjoy the tank. Less lighting generally mean less chance for an algae outbreak. Provided the room in which the tank is, isn’t completely dark, your fish won’t require much bright light. Aquarium light in fresh water aquariums benefit the owner more then the fish.

      • Water changes should not exceed more then 20% in most cases. 10 – 15% regularly is ideal. Large water changes are generally not recommended. In some circumstances they may be effective, however sudden and large environmental changes can severely stress fish making them more vulnerable to disease.

  16. Dear sir
    In our aquarium there is small white color species whose stick on fish and because of that one by one fish is death.
    We also change the water but there is no results this amall species is present as it is
    So kindly suggest some antibiotics for such type of bacteria

    • You should talk to your local fish store professional immediately. Describe the exact symptoms and they will gladly recommend a product for treatment. We do not sell medication and can not diagnose medical problems over the internet. Please see our health guide for a helpful overview of common fish diseases.

    • The obvious consequence will be the rise of waste. The accumulating waste will be converted into ammonia, nitrites, and eventually nitrates. While nitrates can’t be avoided in the aquarium altogether, they are commonly removed by means of regular water changes. Neglecting to remove organic waste with a filter however will likely result in far greater nitrate levels, eventually leading to algae outbreaks and green aquarium water.
      Also see:

      The less obvious result of a “no-filter” setup is that oxygen in the tank may become severely depleted. Oxygen primarily enters the fish tank through surface agitation, which the aquarium filters return usually provides effectively.
      Also see:

  17. Honestly, most fish tanks are pretty depressing. Taking a fish from the wide open sea and sticking them in a little bowl is kinda cruel, so keeping it clean and safe is the least we can do for the little guys, so they have a happy life.

  18. My son is really into fish, so I am going to buy some for him. I am glad I read this article first though. I didn’t know about the pH requirement.

    • You should try to identify any fish disease and then consult your local pet store for available treatments. Here’s a brief description of some common fish diseases that may help you identify the problem:
      Another option is to talk to your local pet store professional for help identifying the cause.

  19. High nitrates is a relative term, and depends on the species and the overall environment. Tab water, treated with a water conditioner, is a safe source, but not directly linked to nitrates. With water changes, nitrates are temporarily diluted. Keeping in mind that nitrates are the end result of decaying organic matter. Algone for example removes more than just nitrates. Proteins, fats and other substances are removed, otherwise they would eventually turn into nitrates. I would say 20ppm would be safe to introduce new fish. The lower the better of course.

  20. I am planning on having Blood parrot cichlids in my aquarium. I cleaned the tank and took some of the water for testing. They told me that nitrates were too high. I bought several products to combat this problem, but still it is unstable. I was then told by a fish expert that the regular tap water is safe. Before I get my fish, how can I get my aquarium environment safe for my cichlids?

  21. Its also not advisable to always leave the lighting system on for 24Hrs. This is thought that light stimulates the growth of algae which may endanger the life of fish in my aquarium. Since this will make them active.

    • You are absolutely correct in that excessive lighting can cause increased algae growth in the aquarium. We generally recommend not lighting for more then 6 hours a day. Less if an algae problem already exists. Of course this is just a general guide and special consideration needs to be given to aquariums that require additional and/or specific lighting such as reef tanks and planted aquariums.

      In addition to light algae also requires nutrients, especially nitrate, for growth. Therefore the lighting schedule as well as nitrate control are the best means for controlling aquarium algae growth.

  22. My unused Aquarium needs cleaning brfore I can again put fish in it. How do I go about this? What products can I safetly use as not to harm the fish. Thanks Agnes

    • Thoroughly rinse the tank with clean, warm, fresh water. If there is some grime buildup on the glass then you can use any mild detergent to clean the tank more thoroughly. A window cleaner will work as well. If you do use a detergent or window cleaner, make sure you rinse the tank assuring ALL of the soap is removed. Soap residues are harmful to fish and other livestock. It is also harmful to the natural nitrifying bacteria, which is needed to keep the aquarium healthy and balanced. Hope this helps.

Leave a Reply

Your email address will not be published. Required fields are marked *