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Cold Water Fish – How To Care For Them

Cold Water Fish – How To Care For Them

Cold Water Fishhttps://bookerpetcare.co.uk/basic-pet-care/cold-water-fish/

This is a very general description of the basic care of cold water fish in a typical household.  This does not relate to marine fish or Tropical Fish. 

Watching an aquarium of fish can be very soothing and relaxing – and addictive.  The way the fish glide through the water is hypnotising, the stillness as they seem to be suspended in mid air.  In order to enjoy this spectacle, fish need daily care and consideration just as all other pets.

Cold Water Fish: Living Quarters:

Cold water fish can be accommodated inside or outside depending on personal preference. The water temperature should be between 15 and 20 degrees. Though a heater isn’t required for cold water fish, it’s a good idea to have a thermometer fitted so you can keep check of the temperature. 

Fish accommodated outdoors generally live twice as long as indoor fish.  Care should be taken for outdoor fish to provide shelter from direct sunlight. 

The size of the aquarium for the fish depends on the size and number of fish.  To maximise the space the fish have, it is recommended to keep numbers low.  Cold water fish do grow to be larger than tropical fish, so a large tank will be required.  It is recommended that aquariums containing small fish have no more than one inch of fish for each gallon of water in the tank.  Larger fish produce larger waste and therefore require a larger aquarium. 

Plants and gravel can be added to the tank to introduce a more natural environment.  The choice of plants may be dictated by which fish you have.  For example java fern, hornwort and Anacharis are suitable in order to keep goldfish happy,   Some fish need such things to thrive, so do your research.  

A water filter will be required, and it’s important to check the water quality before introducing fish to the tank.

There should be no ammonia or nitrite detected.  pH is the level of acidity and reducing pH levels could be a sign of overfeeding.  There are measuring kits available for ammonia, pH and nitrite.  If levels are rising, a water change would be required.

Introducing Fish to the Tank:

First of all, check the water filter, and perform a fishless cycle of the aquarium before introducing one fish to it.  The single fish should be monitored for a full day to check both it and the aquarium health before introducing more. This will reduce the contamination and any hazards being exposed to all the fish.


One of the most common mistakes made by fish-owners is overfeeding.  Fish should be fed only the amount they will eat in a five minute period.  Excess food will simply pollute the water. 

Choice of food for Cold water fish is flakes and pellets and usually cold water fish require feeding 2-3 times per day.


The problem of algae is reduced in a Cold Water Fish Tank as it doesn’t develop fast in the cold water. In order to remove waste from the water, periodic water changes are required.  It is recommended that approximately 50-60% of the water is removed and replaced every week.  This may differ depending on what fish you have  Before fresh water is added, the water should be tested for chlorine or chloramine which should be treated.

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Caring for Tropical Fish

There is more to consider when caring for Tropical Fish, due to their requirement for heat and the associated considerations. 

It is not possible to care for tropical fish in an outside aquarium unless very specialist heating equipment is employed.  

So first thing to consider is the aquarium:











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