Apart from a tank and water, what do I need to know about keeping fish?

Transporting your new fish home

Goldfish are transported home in a plastic bag.  Ensure that the bag in half-filled with water from the tank which the fish was taken from.  Ideally put the bag into a box or pet carrier and make sure the fish doesn’t get too hot or too cold on the journey home.  Be sure not to bounce the fish around too much either.

Gently put the fish (still tied up in the bag) into the water of its tank.  It will float on the top and leave it floating for 20 minutes.  This allows the temperature of the water in the bag to become the same as the water in the tank.  After 20 minutes open the top of the bag and scoop some of the tank water into a jug and pour it gently into the bag, wait for another five minutes so that the water can mix, then push down the side of the bag and your fish will swim out into its new home.


In spite of considerable knowledge available today on tank design, manufacturers still produce the traditional globular bowls with a narrow neck.  These vessels have nothing to recommend them other than their cheapness.  They lack a fundamental requirement, which is that of the surface area ratio of the water they contain.  Fish breath oxygen just as we do, but they extract it from water that is passed over the gill filaments.  The surface area of the water will largely determine the amount of oxygen that a given volume of water will contain.  The ideal shape of a fish tank is oblong, with the tank’s length being about twice its height; this will grant a suitable surface-to-air ratio.

The tank can be all glass, plastic (acrylic) or metal-framed glass.  As a rule always purchase the largest tank you can possibly afford, as it will look better, offer more potential for aquascaping and will allow more fish to be contained in it.

Theoretically, if you have a good balance between plants and fish, then the water will remain in good condition without filtration.  In reality, however, this is rarely the case, and it is advisable to purchase a filter that will remove debris created by the waste of the fish, uneaten food, and dead organisms that sink to the bottom of the tank.

This could be overcome by changing the water in the tank each week; however, this is both extra work and is not actually beneficial to the fish or plants, which require water that is matured - by which is meant that the water has within it the right balance of organisms and minerals conducive to good health.  

The amount of oxygen contained in the water of the tank can be increased by the use of an air pump attached to an airstone or similar porous material.  The airstone should be set near, but not on the bottom of the tank.  Goldfish require more oxygen in the water than do tropical fish, so air pumps are very useful extras; they have the further advantage that the currents they create will help to keep the temperature at a more constant level throughout the tank.  

The tank should be set where it will benefit from daylight - but not direct sunlight. Lighting will be required for healthy plant growth, so a suitable fluorescent or tungsten light should be fitted under the tank canopy.  A glass sheet should be fitted on the top of the tank to act as a condensation plate and to reduce surface evaporation of the water.  Light will be required for about 12 to 14 hours daily.

Goldfish will survive within the range of 0 to 22 degrees centigrade.  There are numerous thermometers that  can be fitted to either the inside or the outside of the tank.

Goldfish kept in home tanks are normally subjected to temperatures at the higher end of the temperature range, and that presents no problem.  In fact, many of the fancier varieties of goldfish prefer a warmer environment.  No fish should be subjected to abrupt temperature changes.

Although goldfish do not have the same need for specific water conditions, water than is neutral to slightly alkaline is probably best.  A pH reading of about 7-7.5 will be required.  Fill the tank up to about 5cm from the top.  It is best to leave the tank alone and running for at least three days so that the water time to matures or you can use a water-aging product.