Fish help to ensure the correct balance of Nature and are \ most attractive when swimming about in the water. Don’t, however, have too many fish. You need 55 mm of fish to each litre (1 in per gallon) of water. It is always better to understock a pool to allow for increase in weight. Fish should have the opportunity of swimming a length which is eight times their own length. Fish, when put into the water, should all be approximately the same size. Always purchase fish for a pool which have already been living in a pool. Never buy fish from a large lake or running stream. Fish eat less in winter than in the summer. It is only necessary in the winter months to give a pinch of fish food on a sunny day. In the summer they should be fed regularly and a good time is early in the evening. It is a good plan to stock the pool with water fleas and lice for these being rich in protein provide the fishes with food. Small red worms may be given and fresh ant eggs, but not the dried eggs which are sold for the purpose.
Goldfish should be bought direct from an English breeder and there are various varieties available. Discuss these with the supplier.
Stock the pool with sufficient scavengers to devour the decaying vegetation. You should have no more than one water snail per 25 litres (5 gallons) of water. Introduce fresh water lice but never fish lice. Water fleas are useful but again these should be purchased and not collected from ain the country.
Never introduce leeches. The fresh water whelk breeds prolifically and scavenges well. My favourite, however, is the Ramshorn snail.
The specialist aquatic nurseryman will always advise the beginner as to the number of each type of plant to use, plus the right number of fish, scavengers and ‘fleas’.
I have found that a tub 750 mm (30 in) across and 450 mm (18 in) deep will accommodate 4 goldfish, 4 oxygenating plants, plus, say, three aquatic plants of the type that throw bothand foliage well above water level, plus a sprinkling of scavengers and ‘food’ insects.