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Last updated Jan 1st 2002

When first buying a fish tank, what are the first things that you should do.


Decide the type of fish you want to keep.

There are 3 main categories to fish: -





Freshwater cold water fish.

These are what are usually kept in garden ponds or non-heated aquariums, these are what usually start the general public keeping fish, like the goldfish (Carassius auratus) is usually one of the first fish to be kept by a hobbyist as hundreds of millions are breed world wide every year.

There are many other species of cold water fish ranging in size shape and colour, size start from 2 inch (5cm) and it all depends on the size of the tank. As you may or may not now there are some weird shaped fish like the sturgeon, with heavy protective scales along its back and swimís along the bottom. As for colour the King of the cold water species is the Koi carp (Cyprinus carpio), which can come in 100ís of different colour forms.

Cold water fish are generally kept in cool water of a temperature of around 8-15 C (40-60 F), some species will live in cooler and higher temperatures but these temperatures are the best recommended for healthy fish.


Freshwater tropical fish.

Freshwater tropical fish is the largest selection of fish open to the public with many thousands of different species, and of the best selling species there are many different colour forms, which have occurred from selective breeding over the years. Again there are many different sizes, shapes and colours, but you cant mix lots of species because a few species are predatory (large catfish and cichlid are generally)

Freshwater tropical fish are best kept in temperatures of around 20-26C (70-80F), you donít get many fish that will live above these temperatures but there are a few.


Tropical Marine fish.

Tropical marine fish are bye far the best for the shire range in colour and shape of fish. (Webmastersís note "I never kept marine fish or inverts but hoping to change that soon. If U would like to write a text for this line the please e-mail me"

Tropical marine fish are best kept in temperatures of around 26C (80F) as a general rule.

The size of my tank.



The size of the tank depends on what U wants to keepÖ Firstly the larger the tank more stable the finale setup would be, but itís not suitable for every one to install a 6í tank in your home.

The owner only decides the size of the tank. They should never be located close to any door or windows to reduce a chill on the tank (the chill is not so important on the cold water species), it also helps to reduce stress of the doors/windows banging close to the tank.


How many fish can I keep.


There are some rules to stocking an aquarium, but I personally thing keep just a few happy fish and not lots of sad fish.


The first stages of fish keeping.


What are the first steps when keeping fish: -


    • Placing the tank.
    • Placing filter, heater, décor in the tank
    • Filling with water.
    • Maturing the aquarium.
    • Buying the fish.
    • Introducing the new fish to their new home.
    • Studying the fish.
    • Enjoying your new hobby.


Placing the tank.

They should never be located close to any door or windows to reduce a chill on the tank (the chill is not so important on the cold water species), it also helps to reduce stress of the doors/windows banging close to the tank. They should be placed off the ground but be placed on a soft material like polystyrene and the whole aquarium should be placed on a solid surface and not slated, to reduce stress on the bottom of the aquarium.


Placing filter, heater, and décor in the tank.

There are three types of filters, mechanical, biological, and chemical, the most common filter is the mechanical, which is where the water is put through a filter media to remove waste particles, power filters, external filters, under gravel filters.

Biological filters use bacteria to convert harmful waste products in to less harmful waste products, "wet and dry" filters, and trickle filter (some mechanical filters can also work as biological). These filters can be affected by chemical treatments, which reduce the biological level of the filter

Chemical filters is basically just a chemical that U place into the filter system and then it absorbs the harmful waste, the chemical then can be removed from the system. A few can be recharged to use again, activated carbon is most common as it absorbs most harmful chemicals but it also absorbs chemical treatments added to the water as a medical treatment.


Filling with water.

When filling your tank, the first thing to remember is to add a de-chlorinater to the water to remove all chlorine from the tap water (chlorine is added to most countries to kill bacteria in the water supply, whatís good for us is not always good for your fish). Itís best to do this in a bucket to make sure the de-chlorinater has worked.

Place all your décor (sand/gravel, stones, rocks, bog wood, ceramic ornaments) in to the tank, remembering to disinfect your décor first (by soaking in boiling water for 5 minuets) to kill and nasty bugs that my be living on it. Then using something that floats like a small piece of polystyrene pore the water into the polystyrene to disperse the water without disturbing the décor.

Once the aquarium is full you can add some plants to it, but you should never add fish at first this is due to the fact of maturing a tank. Maturing a tank means allowing "beneficial bacteria" (good bacteria that break down harmful waste products in to less harmful waste) to grow in the tank and filter systems. If you were to add fish harmful waste products like ammonia would build up in the system and poison the fish quite quickly.

To understand the maturing process better go to "Are bacteria good for a tank?"

Once the tank is mature (after 30 days for fresh water and 90 days for marine) it safe to add fish to your tank. Add fish only in small numbers, just add 5-6 small fish or 1-2 larger fish, to allow the beneficial bacteria to grow slowly and not crash the maturing process. If to many fish are added then the ammonia will rise to quickly and poison the fish and then if not fixed it would then kill them.


Buying the fish.

When going to your local fish shop firstly ask friends who have kept fish and ask where they get their fish and who happy they are. When at the shop there is somethingís you can check like

    • Clean tanks
    • Happy fish
    • Dead fish
    • Good coloration of fish
    • Good lighting
    • Disease on fish
    • Ask staff questions and get useful answers.

If you are happy with the fish you selected then always ask if it will live happily with your other fish. The fish should be captured it should be done with causing as little stress as possible, using 2 nets can help, a beer glass can also be used (usually in marines). Once the fish has been captured it should be placed in a plastic bag, if your traveling a long distance it may be possible to add oxygen to the bag to aid traveling, that depends on the shop. Next get the fish home as soon as possible.

Introducing the new fish to their new home.

Once at home you have to balance water temperature and water quality, firstly float the bag in the water to balance the temperatures, this may take 20 minuets or so.

Then cut the top off and roll the side down to allow to bag the float, next to balance the water quality, this is done buy removing about 25% of the water from the bag and replacing with aquarium water.

Leave the fish to get use to the water difference for 10 minuets then repeat and then once more after that. If after this time the fish still look happy then it should be safe to add the fish.

Studying the fish


Sit down and watch the fish, make sure that the fish up, swimming around and generally doing what fish do. If the fish is lively species, but itís sat on the bottom then itís not a happy fish.

Check the fish daily for spots or red sores that may appear on the fish, these are caused mainly because of stress of moving the fish to a new home.


Enjoying your new hobby.

  Now get a chair, sit down and relax watching the fish, believe me it works.


Are bacteria good for a tank?




Yes, is the answer. There are two types of bacteria Nitrosomonas and Nitrobacter, these are both aerobic bacteria (meaning they use oxygen).

What these bacteria do, is use the harmful waste products from the fish like ammonia and nitrites and convert then in to less harmful products.


Maturing an aquarium

When you first set-up and aquarium it has no bacteria in the system. If you was add any fish to the system, the ammonia produced by the fish would not reduced, but build up to lethal levels From setting up an aquarium it takes about 4 weeks to get it mature naturally, so you should never add fish for that period (unless to speed up the process), a filter may take up to six months to stabilise. You can speed up the maturing process by a number of ways.

  • Adding ammonia, thus feeding the bacteria.
  • Adding a small number of hardier species of fish like barbs and danios (tropical), damselfishes (marine)
  • Adding cultured bacteria to colonise the system



Ammonia (NH3) is produced by the breakdown of protein. Ammonia is alkaline so in water it raises the pH level is the most toxic of the nitrogenous compounds. It has the lowest lethal level of toxicity to fish of only 0.2-0.5 mg/litre. As a result of ammonia poisoning fish die quite quickly.
Nitrosomonas bacteria produce nitrite (NO2) with the presence of oxygen. Nitrite is less toxic then ammonia with lethal levels at around 10-20 mg/litre. The nitrite breaks down the red blood cells making unable to carry any oxygen around the body.
Nitrobacter bacteria produces nitrate (NO3), it has the lowest lethal limit, lethal at 50-300 mg/litre, marine fish are far more sensitive to nitrite and so are eggs and fry.