Aquarium Fish - FAQs

Is a filter necessary?

All fish require filtration. Filters break down toxic waste products converting them into a harmless form. Within the confines of an aquarium, natural processes are not sufficient to maintain a well balanced system. Through surface water movement a filter also aerates the water. Power filters are more efficient than the traditional air driven filter systems, however, the latter is suitable for smaller set- ups.

How many fish can I keep?

The following guidelines apply to a properly filtered aquarium:
Approximately one inch of fish per gallon of water. Build up to this slowly.

Pond:
Multiply length x width and divide the result by 120 to give the amount of fish that can be kept in cm's.

Why does the water go green?

Green water and the green 'slime' often present in aquariums is algae, a simple plant form. The main cause of this is excessive light, particularly where there is long exposure to direct sunlight. Place the aquarium away from windows and ensure cover lights are left on no longer than twelve hours each day. Excess nutrients also encourage algal growth. Ensure fish are not overfed and that partial water changes are carried out on a regular basis. (Also see the article on algae in ponds)

How much and how often should I feed my fish?

Tropical fish require feeding twice daily and coldwater fish once each day. Pond fish do not require feeding over the winter and then once every two or three days in the warmer months. All fish should be fed just enough to be consumed within one minute.

How difficult are tropical fish to keep?

Tropical fish are no more difficult to keep than coldwater fish providing there is adequate filtration. A heater and thermometer becomes necessary, and although not essential, a coverlight shows off the colours of the fish.

Why do fish kept in goldfish bowls often die?

The small volume of water contained in an average goldfish bowl is not sufficient to dilute the waste products from fish. This is compounded by the relatively small amount of surface area, which restricts the entry of oxygen. Overfeeding is also a problem as well as the lack of filtration. Achieving a healthy balanced environment for fish within a goldfish bowl is very difficult. Although perceived as an easy way of keeping fish, the beginner aquarist is well advised to opt for a small filtered aquarium.

How often do I need to clean the aquarium?

Each fortnight a partial water change of about 20% should be carried out. At the same time clean any algae off glass and decorations and rinse filter media in dechlorinated water. Avoid 'spring cleaning' the aquarium as this has a sterilising effect which often leads to fish losses.

Do my goldfish need Oxygen Plant?

There are many aquatic plants available, all of which release oxygen into the water. Although Oxygen Plant produces more oxygen than most it also breaks down much faster and is quickly consumed by fish. Aquatic plants are a beneficial addition to an aquarium, but need not be Oxygen Plant.

Can I get all my fish at once?

Allow a few days 'running in time' before adding fish to the aquarium. Then add a few fish each week until the maximum level is reached. This will prevent the build-up of toxic ammonia known as 'new tank syndrome'.

Can other fish besides goldfish be kept in coldwater?

Mountain minnows, are a small schooling fish which are suitable for coldwater aquariums. Paradise fish are also suitable but can be aggressive to small goldfish. Thats pretty much it! Algae eaters and plecostomus catfish are often offered for sale as 'coldwater' fish. These fish often kill their goldfish tankmates and as they originate from tropical regions, usually die in winter. Be wary of other so called 'acclimatised' tropical fish sold for coldwater - they too usually die in winter. Why not buy a heater and go tropical?

Will my fish breed? Have I got males or females?

Other than livebearing tropical fish, most fish will not successfully breed in a community aquarium. This is due to other fish eating eggs and young, or unsuitable conditions. With a little effort many fish can be encouraged to breed when their individual requirements are met. The sexes can be distinguished in most tropical fish with help from a good reference book. Male goldfish develop white nodules on the gill plates and a thickening of the front rays of the pectoral fins in spring and summer. They are also somewhat slimmer than the females to which they often vigorously give chase at this time.