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Chiswick Pets

32 - 34 Devonshire Road

0208 747 0715

General Information on keeping Aquarium Fish

This page contains general information on aquarium fish and brief details for some popular species.  However please note that this is not a complete guide and each species will have other individual requirements.

Please feel free to come into the shop to ask any questions you may have on fishkeeping, and about any species you are particularly interested in!

Skip to: General Info ~ Water Changes ~ Tropical Tanks ~ Goldfish & Fantails ~ Guppies ~ Common problems



All aquarium fish should live in an adequately sized tank which must have a filtration system.  This is separate from an air pump, which is largely for decoration, the filter is necessary to clean the fish waste and waste food from the water.  Using a filter keeps the water clean and will largely prevent problems such as cloudiness, and increase the amount of oxygen in the water.  Oxygenating plants and air pumps are not strictly necessary in a filtered tank.
Overfeeding is one of the most common causes of problems in aquariums.  We would recommend feeding only a pinch of food every other day, enough that it is all eaten within about a minute.


Water Changes

Contrary to popular belief, it is not necessary to change all of the water in an aquarium, it is in fact better for the fish and the aquarium environment to retain most of the water (in a filtered tank).  This maintains a more stable environment and maintains the beneficial bacteria which help to break down the waste products in the aquarium.
Ideally, remove 15-20% of the water every 2 or so weeks by siphoning it from the bottom of the tank using a gravel siphon- this is a more effective way to also remove the solid waste rather than scooping water from the top of the tank.  Rinse the sponge from the filter in this water (not under the tap).  It is important to rinse the filter sponge each water change, as this not being done is the most common reason for filters breaking down.  Next, add your water conditioner to your fresh water and add to the tank. Done!


Tropical Tanks

The only real difference between a coldwater and a tropical tank is the addition of a heater, obviously raising the temperature of the tank.  Most fish are suited to either a coldwater or a tropical environment though some can live in either. 


Goldfish & Fantails

shibunkin goldfishGoldfish & fantails are some of the most well-known fish.  However, the traditional idea that they can live in a simple, unfiltered bowl and will not outgrow it is not correct, and like all other fish need a filter and a fairly large tank- they are the same fish as people keep in ponds, and can live up to 40 years if well kept!  They are also particularly messy fish, so do need a decent amount of space - many of the smaller 'starter kits' sold for goldfish would in fact become too small after a few months.  Goldfish grow slightly larger and faster than fantails, and can also be aggressive towards their smaller relatives, so the two types should be kept separately.  There are many colours and varieties of goldfish and fantails.



Guppies are another popular fish, which can live in both cold and tropical water.  They are livebearers, which means that if both males and females are kept expect to see babies- though the little ones will need lots of places to hide from the larger fish.  However it is also fine to keep just one sex, many people choose to keep just males as they are the prettier and more colourful of the two.  Guppies come in an enormous range of colours and markings, and stay very small.  This means that they are better suited for smaller 'starter kit' type tanks than bigger fish like goldfish, or that a large group can be kept.  Guppies are sociable fish and can live happily with other small fish and some larger species.  Guppies make a good fish for someone who wants to start out with a coldwater tank but who is considering moving on to tropical later, as the temperature can be gradually increased with the guppies still living in the tank.


Common Problems

Cloudy water: This is usually caused by overfeeding.  Disregard the manufacturers instructions (they want you to buy more food afterall...) and feed only a pinch every other day - the food should all be eaten in about a minute. 

Green algae on tank & ornaments: Algae will grown on/in the tank when there is a lot of light reaching the tank.  If the light on the tank is left switched on for a long time, or the tank receives a lot of sunlight, this is likely to be the problem.  Switching off the light or moving/shading the tank (being careful not to crack it) should help, and algae-eating fish can also reduce the amount.  The algae is not harmful to the fish, but as it is not particularly pleasant to look at it can be wiped away as a temporary solution.

Fish swimming upside down/sitting at bottom/floating: This is usually caused by a condition known as swim bladder.  It can be fatal if not treated, but a simple treatment can be added to the water which is usually effective if used early enough.  Feeding foods other than flake foods (such as bloodworm or daphnia) can help to prevent swim bladder.