Make your own free website on

Keeping Fish: A Beginner's Guide

by James Stapley

Note: feel free to print this out; the easiest way is to copy the entire file to the clipboard (select all the text and hold down control key and at the same time press c) then paste (control+v) it into your wordprocessor or notepad. Then print it.

Keeping fish is one of the easiest and yet most enjoyable hobbies I know of, provided you stick to a few ground rules. Problems generally only result when these break down. Having answered the questions of hundreds of people over the last few years, I think this will save me an awful lot of typing in the future. However, if you do still get stuck, or are confused by something on this page, then feel free to email me.

Although this may well be a repetition of stuff already on the WWW, I hope to make this a comprehensive one stop beginner's site.

I'll start right from the beginning - choosing your tank.

Choosing your tank:

1)The first question has to be 'What fish do I want to keep'. This is best answered by a visit to a good aquarium shop, where you can browse the wide range of fish available. Bear in mind that not all the fish you will see will be compatible with each other. There are 4 main divisions in fishkeeping:

Tropical Freshwater

Coldwater Freshwater

Tropical Marine

Coldwater Marine

By far the most popular is Tropical Freshwater, as it has the widest diversity of colourful, interesting and above all, generally easy to keep species.

The next most popular is of course Coldwater Freshwater; these fish, especially the humble bog standard goldfish are extremely easy to keep and cheap as well as being very forgiving of water quality - though this should not be exploited by substandard conditions.

Tropical Marine aquaria are the pinnacle of fishkeeping acheivement; the fish can be fairly hardy - (but not anywhere near that of the above two groups). However, keeping invertebrates is very difficult and usually well beyond the beginner. The fish are far more colourful than those found in any of the other groups. My recommendation is that you try one of the above groups (preferably tropical freshwater) for at least a year and preferably more, and acheive considerable success with your tank before even considering a marine tank. They require hard work, considerable knowledge, a battery of test kits and a quite substantial financial outlay. Also, an excellent dealer is a must; he must know absolutely everything there is to know about the field and be willing and able to pass on this knowledge to you.

Coldwater marine aquaria are those filled with organisms found on the seashores around temperate latitudes. The livestock are low cost - free because you can collect them. But they still need a lot of looking after as all marine animals are intolerant of bad conditions, although those from rocky seashores will to a limited extent, be able to withstand the rigors of fluctuting conditions. Not many people have these, not to say that this isn't an equally fascinating facet of the hobby; people just generally don't consider it.

2) Once you have decided which branch you want to go in for, you must first choose the size of tank you want. One thing I must stress here is that the bigger the tank, the more success you will enjoy, and the fewer problems you will run into. The absolute minimum in my mind is a 24" by 15" high by 12" wide tank. Bigger than this is better; I had a 4' tank for several years and this is a very good size - although it is a substantial object!!! Some lucky people have tanks larger than this, but 4' is a common and fairly cheap size - I can get them here in the UK for just over 20. Along with choosing your tank you must make sure you have a suitable site available for it. Bear in mind that a tank filled with water, gravel, fish, rocks etc. is a VERY heavy object, and you must make sure that a) whatever you put it on can support the weight and b) so can the floor... You can buy purpose built tank stands, and tanks in ready made cabinets, which look quite nice. You could also build your own, but you must make sure that it can take the weight and that it is absolutely level. I know of someone who built their own stand for a 5'x2'x1 1/2' tank that wasn't quite level - the legs were a different size - and he filled it up. Overnight *CRACK* *WHOOSH* flood... that was just a word of warning; not to put you off, this is very unlikely to happen. You can of course use items of furniture already in your house but make absolutely certain that they can take the weight of the full tank. Make sure once you have chosen or aquired a sufficiently strong base for the tank that you put a layer of polystyrene under the tank, so that any small defects in the surface do not crack the bottom of the tank.

3i)Once you have chosen the right tank for you, you must now choose the equipment to put in the tank to keep the water clean and the fish alive; Fishkeeping has been described as the easiest part of aquaria; it is the water that requires all the attention!

A basic list must include some sort of filter. There are many different types on the market. I personally recommend the Undergravel filter as the most effective and easy filter for a beginner; it works, it's cheap and very easy to look after.

You can power the filter in one of 2 ways; either you must use bubbles from an air pump, or a water pump, usually referred to as a powerhead, which will give a much stronger flow of water through the tank.
The only maintenence required is to 'hoover' a portion of it every week with your water change. (You can buy purpose built gadgets to do this, ranging from battery powered ones to just bits of plastic that use the syphon you use to empty the tank to provide the vacuum cleaning power).
You must ensure that you have a thick enough layer of gravel; at least 2" at the front of the tank rising to at least 4" at the back. This will ensure sufficient space for the NITRIFYING BACTERIA the are so essential for your fish's wellbeing.

Also, internal power filters (e.g. "Fluval" internals) are easy to look after; they only require squeezing clean in a bowl of tank water every 2 weeks or so. I can't stress the importance of NOT using tap water enough. It's the most common beginner's mistake (apart from overfeeding) - using tap water kills the bacteria in the filter that keep your water clean.

I would not under any circumstances recommend the small in the corner air powered filters; they are almost useless in my opinion. For a trouble free life go for another option. Their only use is in tiny tanks and we aren't interested in those here.

Another option is the external power filter; these are very good filters but are more tricky to care for than undergravels. They allow you to use chemical filtration media as well as biological.

One option popular in the USA is the 'hang on' filter; I am not convinced of their efficacy, as they do not hold very much filter medium.

Filtering your Tank: the options:
Type of Filter: Undergravel Internal power filter External power filter Internal air powered (corner) 'Hang on'
Cost: ++ +++ +++++ + ++++
How good is it? ++++ +++ +++++ + ++
Ease of use: +++++ ++++ + +++ ++
Comments: Ideal for beginners Good choice also Expensive but generally worth it. Don't bother. OK for goldfish in small tank? Never used one; don't think they're too good on their own.

5 + = good

1 + = bad.

in the case of cost, 5 = high, 1 = low. This is not a brilliant system, as there are bigger gaps between the different kinds with some, and not as big with others.

3ii)If you've chosen a tropical system you'll obviously need to heat the water; the way to do this is to buy a heater/stat (combined Heater and Thermostat) You put this in the tank according to the instructions (most are submersible, so put these at an angle of 45 degrees along one of the walls. Ensure that there is good flow around the heating element, to eliminate warm and cold patches in the tank. They come in different sizes according to how big your tank is and also how warm you room is on average. Ask the dealer for guidance if you aren't sure.

3iii)You might want to see your fish; a light would therefore be a good idea; again speak to your dealer about the choice of lighting system; you will almost certainly end up with one of the fluorescent tube systems; there are a wide range of different types of fluorescent tubes, all of them giving a slightly different kind of light. I have used a Triton tube and am very happy with it; It's VERY bright. I also later added a Floraglo as I was growing plants and though the extra light would do them good - I was right.

3iv)A hood to keep the fish and light in and dust and small fingers (or paws...) out is also a good investment; the more expensive ones look good; I made my own. Want details?

4) Decorations and that kind of thing. This is what you buy at the same time as your tank, NOT fish. This includes things like rocks, plants, bogwood and other rather less tasteful items of decor (pirate ships, no fishing signs!).

Set up the tank on its stand WITH A LAYER OF POLYSTYRENE UNDER IT. Put all the washed gravel into the tank, 1/2 fill it with water. (To wash gravel, simply place it in a sieve or colander and run plenty of tap water through it while stirring it around until there is no more dirt left). Then put in the filters (N.B. put the undergravel filter plate in BEFORE the gravel) and heaters and any other equipment that might be going in there. Add rocks, bogwood, plants, or any other decorations you might have chosen to the tank. Now you should finish filling the tank with water, switch on the heater and filter and add dechlorinator/water conditioner to the water according to the instructions. After about 1/2 and hour, add one of the commercial bacterial cultures to your tank (e.g. Hagen Cycle); this will ensure that your tank is populated right from the start with the ideal bacteria to keep the tank clean and healthy. Don't forget to turn the light on if you have plants!

NOW LEAVE IT ALONE FOR A WEEK. This is important. I give you this advice as an impartial observer. I know what it's like having all that equipment, but no fish. It's tough; in the long run, however, you MUST do it, for the good of your fish. If you want to know why, it's because of something called the NITROGEN CYCLE. A full explanation can be found at the bottom of the page.

Now, after your week nearly up, change 10% of your water the day before you go to get some fish, with dechlorinated water of the same temperature as in your tank. Finally, the day has dawned! Time for some fish. Take a sample of water in a clean glass jar to the shop where you bought all the tank and equipment from, and have it tested for ammonia and nitrite (of course if you have the test kits do it at home!). Make sure that the water is up to scratch.

I again plead for patience. I know how tempting it is to fill your tank up with fish straight away (god knows I've done it enough times...) but this is WRONG. It almost invariably leads to sick/dead fish.

Above all, enjoy your new hobby! You will probably find you end up with more and more tanks as you enjoy it so much!


Feed the fish! Only as much as they will eat in 5 minutes 2-3 times a day. Small meals are the key! Remove any uneaten food.

Make sure there are no sick fish.


Clean the front glass, using either a scraper or one of those algae magnets - you will often find young people will volunteer to use the algae magnet!

Clean the gravel using a gravel cleaner (ask your dealer for one). While using this, you should aim to empty 10% of your water from the tank. This constitutes what is known as a water change and is vital for the continued health of your fish!

Top up the tank with new water. To do this, get a bucket (buy a bucket specifically for your fish - DON'T use your cleaning bucket, as soap/detergents are bad for fish) and fill it most of the way with cold water from the tap/faucet. Then add a kettle full of boiling water (don't use hot tap water - it is full of nasty dissolved metals) and check the temperature using a thermometer - make sure it is similar to that in your tank. A few degrees difference (1-2 only!) will make no difference. If it's still too cold, add more hot and if too warm, add some cold. Then add some dechlorinator/water conditioner to turn poisonous tap water into fish water. It is possible to add cold dechlorinated water to your tank, but I wouldn't recommend it, as it will lower the temperature of the tank by too much - this is bad for the fish. People get sick when they get cold - fish are the same!


Clean any power filters and if necessary, replace worn out filter materials (e.g. Activated Carbon).

Trim plants/remove dead leaves.


Replace worn out fluorescent tubes.

It's really VERY easy to take care of fish!!! It takes not much more than an hour of your time a week, often much less. Fish are much more interesting than TV much of the time. Buy books on fish; they can tell you much more than I can, and are also illustrated with lots of nice pictures! Learning about your fish will enable you to know more about your fish - which you will want to after a few months of keeping them - I have about 30 books on fish!



The Nitrogen Cycle is what keeps your fish from poisoning themselves with waste products. To enable to Nitrogen Cycle to run, you need to have a healthy population of Nitrifying Bacteria in your tank. These live all over your tank, but particularly in your filter.

Ammonia is excreted by the fish, and anything dead in your tank (including leftover food)- you know how nasty ammonia is! This is converted to Nitrite by one kind of bacteria - Nitrite is still toxic to fish - but nowhere near as bad as ammonia! The nitrite is then converted to Nitrate by another kind of bacteria. Nitrate isn't very toxic, except in large amounts (50 mg/l+). To get rid of nitrates, you need to do water changes.

A diagrammatic representaion of the nitrogen cycle:

AMMONIA -------------> NITRITE ------------> NITRATE

     >Nitrosomonas>            >Nitrobacter>

TOXIC!                             HARMFUL                  OK in moderation - use water changes to keep in control.

The words in italics are the type of bacteria that does the work. They grow very slowly, so give them a head start by putting them into the tank when you first set it up using a bacteria culture (e.g. Hagen Cycle), and every time you add new fish. You don't need to add it every week, but follow any directions on the pack otherwise.