26 March 2004


Although goldfish are easy fish to keep, they do have some particular requirements and need good care and attention if they are to be healthy and happy.


A TANK. It doesn't matter if it is plastic or glass but it must be a proper tank - bowls are completely unsuitable for goldfish no matter what the pet store may tell you!

SIZE OF TANK: Fancy goldfish (round bodies, twin tails) need tanks which allow at least 20 US gallons (16 UK gallons) per fish. Common, comet or shubunkin goldfish however (long bodies, single tails) need at least 20 US gallons (16 UK gallons) per fish to, but a long tank NOT the tall tanks. This size rule applies regardless of how old or big the fish are, e.g. three 1-inch goldfish need a 60-gallon tank just as much as three 6-inch goldfish. You can keep them in a smaller tank when they are very young but they will quickly outgrow it and water quality will always be a struggle to maintain so you will soon have to upgrade, which is expensive.

The main reason for this large space requirement is that goldfish are particularly messy creatures which produce large amounts of bodily wastes, far more than most tropical fish. These wastes can very quickly poison a small volume of water, whereas a large amount of water dilutes them and make it much easier to keep the tank clean, safe and stable.

The second reason is that goldfish need lots of space to achieve their full growth and lifespan. Goldfish can in fact grow well over a foot long and live for more than 20 years if cared for well. However, if kept in cramped unhealthy conditions they become very prone to diseases and weakness. These unfortunate fish die young.

SHAPE OF TANK: Goldfish tanks need a big surface area for good oxygenation, so a basic rectangular shape is best. Avoid tall, narrow, or oddly shaped tanks, such as those like two towers with connecting tunnels. Always fill a new tank and examine it very carefully first for any leaks or cracks before you trust it with your precious fish.

POSITIONING THE TANK: Place the tank out of direct sunlight and on a surface definitely strong enough to take its weight; a specially designed stand from the fish store is safest. Don't place it where the fish will be constantly startled by noise and movement or jolted by passing people. Site it close to a power supply (you will need 2 - 4 sockets) and to a water supply, as you don't want to be lugging heavy buckets up three flights of stairs every week!

PREPARING THE TANK: When you first set up your tank, don't put any fish in it for at least 24 hours. Put in the substrate, plants and ornaments, fill it up, turn on the filter, air supply and light and let it run like that. After 24 hours, when the water is completely clear, the temperature has levelled out and you are satisfied that all the equipment is functioning properly, you can add fish.

ESSENTIAL EQUIPMENT: Your tank MUST have the following to keep your goldfish safe and healthy:

1. LID / HOOD. Goldfish have been known to make fatal jumps out of open-topped tanks, plus air-borne pollutants such as cleaning sprays, smoke or cooking fumes can poison them, so keep the tank covered.

2. FILTER. Filters remove wastes and chemicals from the water, keeping it clean. Without one, the water will become foul very quickly so this is a "must-have" piece of equipment. There are several types available:

* Sponge filter
* External canister filter
* Hang-on-back (HOB) filter.

All of these types work well, but do ensure it is the right size for the tank, i.e. if you have a 40 gallon tank, choose a filter big enough to handle this size or ideally even more; extra filtration is a very good idea where goldfish are concerned.

3. AIR SUPPLY. Yes, goldfish do breathe, but unlike us they breathe oxygen dissolved in water, not atmospheric air. Water is only oxygenated at the surface so plenty of bubbles and splashing here is essential. Many filters have a built-in air supply feature, but if yours does not then you need an airpump, a length of airline tubing and an airstone or bubble wand.

If you ever notice your fish gasping at the surface it is most likely because they are not getting enough oxygen so increase the air supply immediately. The same goes if the tank temperature rises above 75F, as warm water holds much less oxygen than cold.

4. CLEAN DECHLORINATED WATER. The chlorine and other additives in drinking water are highly toxic to fish so NEVER PUT UNTREATED TAP WATER INTO THE TANK! You first need to treat the water using a de-chlorinator (also sometimes called a water conditioner). Make sure the brand you pick removes chlorine AND chloramine, and always use it whenever you add new water to the tank. If using well-water then have it tested first for heavy metals and other dissolved substances; some can be very toxic to fish.

5. FOOD. Goldfish are omnivores and therefore need both meaty and veggie foods. A varied diet, which ensures they get all the proteins, fats, fibre, vitamins and minerals they need, is essential; a constant diet of generic goldfish flakes just isn't enough. There are a number of excellent foods available: Hikari, Pro-Gold and Tetra are all very good brands. Feeding is explained in more detail later.

6. BUCKETS for water changes (unless you have a sink or toilet handy into which you can directly drain tank water). Water changes are messy affairs; don't imagine you can just scoop a little water out and put some back! You'll be siphoning gallons of it out into a bucket every week. Because household detergents are lethal to fish, get the fish a new bucket of their own and clearly label it for tank use only. NEVER use soap or detergents to clean the tank or equipment and don't wash your hands with soap before touching / feeding the fish.

9. GRAVEL SIPHON to clean the gunk off the bottom of the tank. This looks like a round clear plastic tube with a length of flexible plastic hose attached. Gravel cleaning is explained later.

10. WATER TESTING KITS. There are four main substances which you absolutely MUST monitor regularly: ammonia, nitrite, nitrate and pH. These substances are always present and are fundamental to the way a fish tank works (this is explained in "Cycling", below). However, they are lethal to your fish if they rise above certain levels so you need to measure them regularly. You will need these kits immediately, i.e. on the very first day the fish go into the tank. There are several different sorts available; the main ones are dip strips, liquid reagents and tablets. The liquid reagent kits are the most accurate and are very easy to use. Aquarium Pharmaceuticals does a good range.

11. DECHLORINATOR (water conditioner) to remove chlorine and chloramine from your tap water as mentioned above.

12. NET for catching the fish or scooping things out of the tank. Make sure the net you buy is at least twice the size of your largest fish, or they can be hurt when you capture them in it. As an alternative to a net, you could use a large clean plastic pot (like a yogurt pot) for catching your fish.


1. LIGHT. Providing artificial lighting in the tank is not essential but it helps you enjoy your pets in the evening and lets you grow plants. However, if you do have tank lights then you must switch them off at night. Goldfish need a natural day-night rhythm the same as you do. Only ever use lighting designed specifically for aquarium use, NEVER ordinary electric lights because of the risk of electrocution. Many tank hoods now come equipped with built-in lighting.

2. SUBSTRATE. This is whatever you use to cover the bottom of the tank, usually some gravel or pebbles. It isn't necessary to have substrate (and many goldfish keepers prefer not to) but your fish will enjoy rooting through it and it helps if you want to grow plants. The best substrates for goldfish are fine-grade gravel, large pebbles, sand or rounded glass nuggets. You need to clean the substrate weekly because dropped food and fish wastes accumulate in it (the cleaning process is explained below).

3. ORNAMENTS/PLANTS. It doesn't matter how you decorate the tank as a natural piece of wood with real plants or a fluorescent plastic castle sitting atop multicoloured gravel are equally good from a fish's point of view! It's down to your personal taste. However, avoid any hollow ornaments as these cause health problems; if you must have one, clean it out very thoroughly once a week. Move large or heavy ornaments and clean underneath them regularly, as toxic bacteria can build up there. Goldfish do eat plants so if you buy real ones be prepared for them to be nibbled! Java Fern or Java Moss are the only plants they won't eat and these also grow well in most conditions, so are ideal for beginners. Finally, NEVER put untreated wood, leaves or anything else which might decay into the tank as they will cause major problems. Similarly, don't put in stones picked up outdoors as they may affect your water chemistry, or put in any ornaments which are not actually designed for aquariums as they may be toxic.

10. THERMOMETER. A tank thermometer is very useful, especially if you live somewhere that has very hot summers or very cold winters. Goldfish prefer a temperature of between 65F and 75F. Below 50F they will go into a form of hibernation and above 82F they will begin to suffer.

11. MAGNETIC ALGAE-SCRAPER. This is definitely the easiest and quickest way of removing unsightly algae from the tank walls.

12. HEATER. Goldfish are coldwater fish, so average room temperature is fine for them ordinarily and a heater is not needed. But you might consider getting one if your tank gets very cold in winter or the temperature fluctuates greatly between day and night, or to treat some diseases. If you do get one, then also get a heater guard to avoid burns.


Choosing new goldfish is enormously fun, but there are a few golden rules of successful stocking:

1. Only choose fish which are healthy, alert and swimming well. If there is any sign of disease or injury in the tank - even if the fish you choose doesn't seem to be affected - don't buy any. When you are more experienced at fishkeeping then you can take home the 'rescues'.

2. Only get 1 or 2 fish at a time, e.g. if you have a 50 gallon tank don't put in 5 fish at once, just get 1 or 2 to start with and then gradually add the rest over the next few weeks. This prevents the tank becoming overloaded with dangerous wastes all at once (see Cycling).

3. If you have an established tank with fish already in it, put new arrivals in a separate tank for at least 4 to 6 weeks before adding them to the main tank. They may well be carrying diseases with them and you do not want to infect your whole population.

4. Gradually acclimatise the fish to the new water. The temperature and chemical composition of the water the fish came from will be vastly different to your own water supply, so a sudden introduction to it will stress the fish very badly, (just imagine how comfortable you'd feel if I suddenly transported you from a tropical beach to the top of Mount Everest!). Instead, gently pour the new fish and its travelling water into a separate container which holds at least 1.5 gallons (a bucket or big plastic box is ideal), making sure there is enough water to cover the fish completely. Now add half a cupful of water from your tank to the container every 5 minutes. By the time you have poured in half a gallon of water the fish will be completely acclimatised to the new temperature and chemistry. Net it out of the container and place it gently into the new tank. Throw away the water in the container - DON'T pour it into your tank as pet store water often harbours diseases and parasites.

4. Give your fish time to get used to its new surroundings. Leave the tank lights off for the first day, keep movement and noise round the tank to a minimum and ensure that it has somewhere in the tank to hide. It will come out and begin exploring when it feels more confident. It is also best not to feed it on the first day.



Fish expel solid wastes and liquid ammonia - lots of it! The solid wastes decompose and also release ammonia. Ammonia is highly poisonous and can very quickly accumulate to lethal levels. You can't see it, touch it or smell it however, and for this reason it is sometimes called 'the silent killer'.

However, there are good bacteria living in the filter which convert ammonia into another substance: nitr*I*te. Nitrite is also poisonous to fish, but a different set of bacteria convert it into yet another substance: nitr*A*te. No bacteria will convert nitrate, but this is only harmful in very high concentrations and is easily kept in check by weekly water changes.

Fish = ammonia = nitrite = nitrate = removal: this is the 'cycle' of the tank.

This all sounds great, but when you set up a brand-new tank there are none of these bacteria to covert the ammonia and nitrite, so the levels build up and the water quickly becomes toxic. 'Cycling the tank' is therefore the first job of a new tank owner. It simply means the process of growing a colony of bacteria to convert all the ammonia and nitrite and keep the water safe for your fish. Because of the extreme toxicity of ammonia and nitrite, cycling the tank properly is absolutely vital!

It takes about a month for a new tank to cycle. During the first 2 weeks the levels of ammonia and nitrite will rise and during the second two weeks they will fall. After the fourth week, no ammonia or nitrite will be present, only nitrates, which means the bacteria have grown and the cycle is now working. However, while these bacteria are building up obviously there are not enough of them to convert all the ammonia and nitrite, and therefore you need to physically protect your fish by performing regular water changes to keep the levels low. (Incidentally, you don't need to add any bacteria to the water - they naturally appear on their own. If you do want to help the cycle along however, the only product which does this is called Bio-Spira by Marine Labs).

This is how to cycle a tank:

Day 1: Test the water for ammonia, nitrite and nitrate using your test kits, once in the morning and ideally once again in the late afternoon. If you find either ammonia or nitrite present above 1.0 ppm, change enough water to get the levels down to between 0.5 and 1.0 ppm. If they are already at this level however then you don't need to change any water.

Day 2: Repeat.

Continue with this process every single day until absolutely no ammonia or nitrites are present and only nitrates are seen. And that's it - you've cycled the tank. Easy, isn't it?! All the substances and processes sound complicated, but actually dealing with them is very easy as long as you are attentive and vigilant and willing to lug around buckets of water frequently. Once you have successfully cycled the tank then you only need do tests and water changes once a week.


1. The cycling process may take three weeks or it may take six: each tank varies a little. About a month is usual though. If your tank is still not cycled after 6 weeks then something is wrong: these are common problems to check for:

too many fish in too small a tank overfeeding something rotting in the tank (e.g. a plant or some food buried in the gravel) the filter is inadequate / not working properly inadequate aeration (the bacteria need oxygen too) pH is too high or too low temperature is too high or too low.

2. The amount of water you change during cycling will vary: some days it might be 50% or even 80% of the total volume, other days only 10% or even none at all. NEVER assume the water is safe after a water change however - always test it again to make sure the levels really have gone down far enough. If they haven't then change more water and test again... and again if necessary.

3. Don't be tempted to change enormous quantities of water to try and keep the ammonia and nitrites at zero all the time; you must leave some in the tank otherwise the bacteria will not build up and the tank will never cycle. Remember: between 0.5 and 1.0 is best. Don't clean your substrate too thoroughly either as bacteria grow there as well as in the filter.

4. Feed your fish extremely sparingly during cycling as the more food you put in, the more ammonia builds up. Only feed once a day or even only every other day, and only as much as they will eat within two minutes. Check that no food gets left uneaten as it will rot and cause the ammonia to rise.

5. If you ever add more fish to the tank, changing all the water at once, remove or change all the substrate or change the filter media (which you should never need to do if you clean it gently in old tank water once a month or so) then be aware your tank may undergo another cycle - test and check.


TANK CLEANING. As mentioned, goldfish are very messy fish so their tank needs thorough cleaning, ideally once a week (or if you really cannot manage this then once every other week). The fish should stay in the tank while you clean it, but be careful not to trap them with the siphon or pour new water heavily onto them.

This is how to clean a tank:

1. Switch off the filter, light and heater if you have one, and remove the tank hood. Spread out an old towel or some absorbent paper nearby to catch water draining from the plants and ornaments when you lift them out. Remove these from the tank (you don't have to remove live plants however, only plastic ones) and wipe them clean with your sponge. Any hollow ornaments should be scrubbed out very well with hot water. Leave these out to air-dry while you finish cleaning the tank.

2. Wipe the algae off the tank walls and ornaments using an algae scraper or a sponge. You can however leave some on the back and/or side walls to provide food for your goldfish if you wish. Wipe the hood and/or light if these are coated with algae or gunk. If there was a lot of algae the tank water will look quite murky by now but don't worry - this is normal.

3. Next, clean out the poop and old food on the tank bottom with your gravel siphon. You stick the round tube in the tank, suck on the end of the attached hose to start the siphon movement and quickly put that end in a bucket or sink to allow the dirty water to drain out. Move the tube up and down and around in the gravel, making sure you get right down to the tank bottom. Both the gravel and wastes will be sucked up into the tube, but the heavy gravel falls back down and the lighter wastes flow out into your bucket. It's a clever thing! Gradually work from one end of the tank to the other, making sure every area is thoroughly 'vacuumed'. Even if you don't have any gravel you still need to clean the bottom of the tank and the gravel siphon is still the easiest way of doing this. The siphoning process removes water as well as wastes so the gravel clean actually forms part of your water change, which is the next step.

4. Change the water. Goldfish tanks need 50% of the water changed week to keep the nitrate level down. You may find in fact that the gravel clean has removed enough water already, but if more is needed then drain any further water out by just holding the gravel siphon in the tank. Then fill the tank back up with clean fresh water, taking care not to pour it in so fast that you blow the fish or gravel around!

Remember the following key rules when you replace any water:

it must be the same temperature as in the tank. To test, simply put your hands in the new water and tank water at the same time. Does it feel exactly the same? If yes, that's good enough. If you can't do this (e.g. if your water supply is too far away) then use a tank thermometer to check.

it must be dechlorinated

it must be the same pH as in the tank (discussed in more detail later).

4. Re-arrange the tank decor. Smooth the substrate with your hand, re-arrange the ornaments and plants, replace the hood, switch on the light, filter and heater and check they are all working properly. Make sure the fish have settled down.

If you have a sponge filter or an internal power filter, it is a good idea to gently rinse out the sponges in some old tank water (never tap water!) as part of your weekly routine. Don't scrub them or you'll lose the bacteria and affect the cycle. Just very gently squeeze most of the dirt out, and don't allow the sponges to dry out as this will kill the bacteria. Put them back in the tank or filter immediately after cleaning.


Yes, we've already talked a bit about water quality so you now know that ammonia and nitrite must not be present and nitrates ought to be kept down by weekly changes (it is best if these are always below 20 ppm). However, there are a couple of other crucial water quality factors which you must keep an eye on:

PH (ACIDITY / ALKALINITY). All fish have a preferred pH level: some like acid conditions (below 7 on the pH scale) and others like alkaline conditions (above 7 on the pH scale). Goldfish prefer a pH of between 7.0 and 7.6, which is neutral to slightly alkaline. They will happily adapt to a pH outside this range but NOT lower than 6.5 or higher than 8.5, as these levels are dangerous. More importantly, the pH must be completely steady, i.e. never rise and fall. A pH which rises and drops sharply is far worse than one which is outside the fish's preferred range but holds steady; the fish will become very distressed in changing pH levels. pH steadiness is directly related to water hardness.

HARDNESS: All water contains various dissolved minerals and salts and it is these that regulate the pH. Broadly speaking, hard water has a high level of these minerals and soft water a low level; hard water holds the pH level steady and is more alkaline, while soft water does not hold the pH steady and is more acidic. When you first set up your tank, take a sample of your water to your local fish store and ask them to test the hardness (the GH and KH) for you. If your water is reasonably hard (the KH is over 125) and the pH is neutral or slightly alkaline, then you need do nothing at all - this is ideal water. If the water is soft and the KH is low (below 100) however, then you will need to artificially 'harden' it to hold the pH steady. If the KH is very high (over 350) and the water very alkaline then you will need to artificially soften it to lower the pH.

You can artificially harden water very easily with ordinary baking soda (sodium bicarbonate). This process is called 'buffering' the water. Add the soda to the tank, a teaspoonful at a time and keep measuring with your pH kit until it shows a pH of about 7.2 - 7.4. Use a KH kit to check that the KH is over 80, ideally over 100. The pH will now remain steady until your next weekly water change, at which time you'll need add more soda to compensate for however much is lost in the change. You can also add crushed oyster shells or crushed coral to the filter; this achieves exactly the same effect and is much longer-lasting than baking soda.

Softening very hard or alkaline water is not so easy. Putting peat moss into the will remove some minerals and add acid. You will need to monitor the pH very carefully and replace the moss as it loses its efficiency. Other alternatives are to buy a reverse osmosis kit - ask your pet store for advice on this as they are very expensive - or to collect rainwater and mix this with your tap water.

You should test the pH and KH every week as part of your cleaning and maintenance routine to make sure that all is well. If you notice any change in the pH, then immediately examine the tank to find out why. These are some common causes of pH changes:

Rock ornament. Some rocks, such as chalk, limestone, tufa or marble release chemicals into the water which causes the pH to rise. You should never keep these rocks in the tank. Driftwood ornament. Driftwood (also sometimes called bog wood or jati wood) can lower pH. It is not recommended for tanks with an already low pH. High nitrates or rotting food, plants or fish: organic decay processes produce acid, which can lower pH. Water change: if the pH from your water supply is different to that in your tank (because it has a low buffering capacity or high carbon dioxide content) the pH can swing drastically. Make sure this doesn't happen by buffering the water before it goes in the tank, as described above. Carbon dioxide in the water. Some water contains a lot of carbon dioxide, which produces carbonic acid and lowers pH. To test if CO2 is the cause of your pH fluctuations, pour a small amount of tap water gently into a bottle and test the pH. Now shake the dickens out of the water in the bottle! Test the pH again: if it has risen, then CO2 is the cause of the pH changes. You will need to thoroughly aerate / agitate any new water in future to dissipate the CO2 and get the pH level up before adding it to the tank.


You can really have some fun with your goldfish at feeding time! However, it is very easy to overfeed and this can lead to serious health problems. At most, goldfish should only be fed twice a day and only what they can consume within TWO minutes, or three times a day but only what they can consume within ONE minute. Make sure that no food is left sitting on the bottom or floating after feeding time is up - remove any excess. It doesn't seem like much food, but they only have tiny tummies! Plus, they sift algae and other invisible organisms from the tank water all day, which supplements their diet.

Some breeds of goldfish, such as moors, telescopes, bubble-eyes or celestials, do not have very good eyesight so make sure they get a fair share of the food. If you see that some of your fish are missing out at mealtimes, then you can hand-feed them. To do this, simply hold a little food between your finger and thumb and offer it to them just below the surface. Occasional hand-feeding is in fact good for all your fish because it helps build trust between you and them and is a very enjoyable form of interaction.

Goldfish need a varied diet and happily there are many foods available for them. Here are some suggestions, most of which should be available from your local fish store:

flakes, either complete food or spirulina (algae) flakes pellets (either sinking or floating, although sinking are much better) freeze-dried live foods, such as bloodworms, daphnia or shrimp frozen live foods, such as bloodworms, brine shrimp, mosquito larvae or daphnia gelled live foods

Keep a selection of three or four different types to ensure your goldfish is getting a healthy balanced diet. It also gives them a bit of interest to have a different food each day - they look forward to it. However, most foods have a shelf-life, e.g. dry flakes and pellets should not be kept longer than 3 months, maximum. It is best to buy the smallest sized containers of food and use these up quickly, replacing them regularly with fresh food.

In addition to bought foods, you can also feed your goldfish with a variety of vegetables and fruits; most enjoy peas, spinach, cauliflower, carrots, lettuce, cucumber, tomato, zucchini, eggplant, orange or lime slices, strawberries, raspberries, banana, and peaches. With the vegetables, blanch them briefly first in boiling water before feeding as otherwise they will be too tough for the fish to chew. It is ideal to feed vegetables at least once a week, but only feed fruit occasionally as a treat as it contains too much sugar. I find it best to feed vegetables mushed into small mouth-sized pieces, and fruit as whole chunks dropped into the tank which the fish can suck at for a couple of hours, but do experiment and find out what your fish prefer.

Never feed your goldfish bread, biscuit or cracker crumbs, rice or potato. Their digestive systems do not deal well with carbohydrates so these foods cause health problems.


TOUCHING THE FISH: You should avoid touching or stroking your goldfish, even if it enjoys being petted (some fish do). Fish have a protective slime-coat over their bodies which helps keep out diseases and if you touch them it removes this coating and leaves the fish much more vulnerable to problems. If you do ever touch your fish wash your hands thoroughly afterwards as occasionally fish diseases can affect humans.

DISEASE AND INJURIES: As long as the fish are in the right-size tank, the water quality is excellent and they are not overfed or stressed, your fish should remain generally very healthy. However, diseases or injuries occur from time to time in even the best-run tanks, so check your fish every day and make sure all is well. If one of your fish appears ill or injured, it is best to isolate it quickly in a separate tank or other suitable container with its own filter and air supply. This prevents disease spreading to the other fish and also gives the afflicted one peace and quiet in which to recover.

If your fish does become ill, there are numerous medications available in most fish stores and the temptation is to turn to these straightaway. However, there are some golden rules about medicating fish:

Always be absolutely certain what disease the fish has before you attempt to treat it; some fish diseases can be hard to diagnose accurately and treating with the wrong medication can make problems much worse. Get help with a diagnosis first.

Don't medicate unless it is absolutely essential. Several diseases, such as finrot, can be cured in the early stages simply by keeping very clean water, increasing the temperature and adding a small amount of salt to the tank. Fish medications often include very unpleasant chemicals which stress the fish and can crash the cycle, so don't make a problem into a disaster by panicking and pouring things in unnecessarily.

Never mix medications; this can cause bad side effects. If one medication is present in the tank and you want to use another, then put activated carbon in the filter first for at least 24 hours to clean the previous medication out and/or do a series of water changes.

Take out any carbon in the filter before adding medications otherwise it will simply remove them from the water.

If possible, add medications to a separate 'hospital' tank rather than the main tank (except in cases of parasites or very contagious diseases when the main tank should be treated). There is no need to stress all the fish if not all of them are ill.

Test the water quality every day: many medications attack the bacteria in the filter as well as the disease, causing the cycle to crash. If this happens, finish the course of medication but treat the tank as a cycling tank (i.e. daily tests and water changes).


It is very hard at first to know what to do and when! There seems to be so much to think about: water, food, cleaning, filter, pH etc. Actually, once you get into a set routine it is very easy to care for your goldfish.

Below is a suggested routine (for a cycled tank) which should be more than enough to avoid most problems and enjoy your fish.


Morning: Switch tank lights on. Check all fish to make sure they are healthy, swimming well, etc. Feed flake or pellet food.

Evening: Check fish all OK. Feed frozen, dried or gelled food, or vegetable food. Switch tank lights off last thing.


Test ammonia, nitrite, nitrate and pH. If the test results are all OK go through your normal cleaning routine (described in 'cleaning' above). Spend some time watching your fish to make sure all are healthy, active and behaving normally.

If the test results are NOT right however, e.g. the ammonia level has risen, then immediately perform a water change large enough to bring ammonia / nitrite down under 0.5, or add baking soda to buffer the pH, or whatever is required. Then search out the actual reason for the poor water quality and put it right.

Perform a 50% water change. Remove sponge filter media if using this and wash it out gently in old tank water (never tap water!) and replace. Replace any carbon filter media being used and clean the impeller of the filter if it has one. Check all equipment is functioning properly. If an undergravel filter is being used, clean out the gunk from under the plate by putting the siphon down the uplift tube.


Replace the lighting (neon tubes lose their effectiveness after a while, even if they still look as bright). Replace the rubber diaphragm in the airpump if you have one.

And that's it! You are now a professional fish-keeper - well done!



IS THE WATER CLOUDY? Cloudy water often occurs during cycling while the tank settles down or if you disturb the substrate a great deal during cleaning. It should clear within a few hours or days, but adding carbon to your filter can hasten this process. If the tank is cycled, however, then persistent cloudiness can indicate a bacterial bloom brought on by too many nutrients in the water. Cut down on feeding, clean the gravel and filter sponges, and do more regular water changes. Adding live plants can also help.

IS THE WATER GREEN? Algae (tiny single-celled creatures) will grow anywhere containing water, light and nutrients. All tanks have some algae - it is normal - but green water means there is far too much of it. Move the tank out of sunlight and add some live plants to help remove the nutrients. Perform more water changes and ensure you are not overfeeding and that the filter is working properly.

IS THERE BROWN OR GREEN STUFF IN THE TANK? Algae again, I'm afraid. All tanks have it and in fact some of it will be eaten with relish by your fish, but the only way to get rid of it is to keep wiping it off regularly. Lots of live plants will help keep it down too.

IS MY FISH RACING ROUND THE TANK? Racing round the tank is not normal; goldfish usually swim with a steady grace, except when they are spawning (the fish will be chasing each other, if this is the case). It usually indicates problems with the water quality - did you remember to dechlorinate? Test your water for ammonia, nitrite, nitrate and pH and perform a water change immediately or buffer the pH, whichever is appropriate. If the fish still races then it has a health problem - ask on here for advice.

IS MY FISH SITTING ON THE BOTTOM? It may well be asleep or resting. Fish sleep on and off during the day and night, but they cannot close their eyes so you may not be aware at first that a fish is asleep. Try going up to the glass and making some movements - a healthy fish will come up shortly to investigate, an unwell fish will stay on the bottom. Fish that are ill will stay on the bottom for long periods.

DOES MY FISH ALWAYS BEG ME FOR FOOD? In the wild, goldfish are constantly searching for food because they never know where their next meal might be coming from. It is therefore instinctive for them to keep asking for it even when they are not really hungry. They will beg you for food all day if you're near them, but you certainly should not feed them more than 2-3 times a day. If they look particularly pleading you can occasionally give them a small piece of fruit or vegetable as a treat in addition to their regular meals, but no more than that.

IS MY FISH ALWAYS HIDING? It may be feeling nervous. Is there somewhere in the tank for it to hide? Is there a lot of noise or movement going on by the tank? Alternatively it may be feeling unwell - check the water parameters and examine the fish closely for signs of disease.

IS MY FISH RUBBING ITSELF ON THE ORNAMENTS OR SUBSTRATE? A fish rubbing or flicking itself on things in the tank has irritated or painful skin. First test your water - have the ammonia or nitrite risen or the pH changed? If the tests are OK then it may well have a parasite problem.

IS MY FISH CHANGING COLOUR? Many goldfish change colour gradually to some extent as they grow older - this is natural - but sudden or profound changes of colour indicate something is wrong: red or black patches indicate ammonia burns, a white film indicates the pH has gone severely askew, paleness all over (including gills, eyes and inside the mouth) may indicate anaemia, dots or splotches of odd colour can indicate fungus or parasites. Ask for help with a diagnosis.

IS MY FISH CHASING OTHER FISH? You may have a bit of a bully who wants to protect his food or territory, or the fish may be spawning. Sometimes common, comet or shubunkin goldfish (slim shape, single tails) will chase and/or nip at fancy goldfish (rounder, twin-tailed) because the fancies cannot swim as quickly. There is little you can do to stop a bullying fish, except isolate it from the others with a tank divider or separate tank.

DOES MY FISH HIDE WHEN I TURN ON THE LIGHT? Quite simply, it is painfully dazzled. Goldfish cannot close their eyes remember, so it has no alternative but to rush down and try to hide its eyes until they adjust to the light. It helps to turn a nearby room light on a few minutes before turning on the main tank lights so the fish's eyes can adjust more comfortably.

IS MY FISH FLOATING / UPSIDE DOWN / SWIMMING AWKWARDLY? Fish have an air-filled organ in their bodies called the swim bladder. By regulating the pressure within this, the fish is able to remain upright and move up and down in the tank. If this because obstructed or diseased however, the fish loses its equilibrium and either floats at the surface (either upright or upside-down), sinks like a stone and/or struggles to swim. This is often caused by constipation, so fast your goldfish for three days and then feed it a pea, de-skinned and mushed, as this acts as a laxative. If this does not work then there may be an internal infection.

DOES MY FISH HAVE WHITE SPOTS ON ITS SKIN? There is a common parasite called ich, or whitespot, which commonly attacks fish. If your goldfish develops what looks like grains of salt scattered over its skin, then this is the likely cause. If the dots look more like little tufts of cotton wool, however, then the fish may have fungus or a parasitical infection called columnaris. Seek help with a diagnosis.

ARE MY FISH'S FINS RAGGED AND RED-STREAKED? Either the fish has been attacked by another fish, the nitrites are very high or it has a disease called finrot. Keep the water quality perfect and seek a diagnosis.

IS MY FISH GASPING AT THE SURFACE? There is insufficient oxygen in the water: increase the oxygenation immediately by turning up the filter flow or adding another airstone, and find the root cause of the problem. Sometimes fish do this when you clean the tank; this is due to the gunk released into the water, so a water-change should cure them quickly.

IS MY FISH LYING ON ITS SIDE? A fish that is lying on its side is feeling extremely ill. Check your water parameters first: are they all OK? Any number of diseases can result in this behaviour - seek a diagnosis quickly.

And that's it! You now know the basics of goldfish keeping and can keep your pet alive, happy and growing. As you acquire more experience you will pick up additional information on the way and may end up being an expert yourself.

Please bear in mind though that sometimes, despite the best or most professional care and attention, some goldfish die. We don't always know why they do. If your fish is obviously feeling ill, then seek help immediately of course, but do NOT blame yourself if it dies because it probably isn't anything you've done wrong. If it is because you did something wrong, however - if you forgot to dechlorinate the water or over-fed them or didn't test or change the water frequently enough - then still do not blame yourself, but do learn from the experience. Look at what went wrong and plan how you will do it differently next time. Even the best fish keepers make mistakes occasionally.

Good luck!

Writen by "Emma"