The colour and lively movement of ornamental fish are a great asset to a pool and they also perform the valuable service of controlling insects. But they are not compulsory. The notion that so many oxygenators plus so many inches of fish equals pool balance is mistaken. A pool can have a few fish or none at all and still be entirely successful, although it will be missing a good deal in potential interest.
The recommended rate for initial stocking – 2 to 3 in. of fish for every square foot of water surface area – is therefore a maximum which you should not exceed; it is certainly not a minimum requirement, and you can start off with a good deal less without prejudicing the success of the pool in any way.
Types of hardyfish that can be safely mixed together include goldfish, shubunkins, the comet longtail variants of both, orfe, rudd and tench. The Japanese Koi and Hi-goi Carp which are so popular with fish fanciers nowadays are perhaps the most vividly colourful fish that can be introduced into an outdoor pool. It must be said, however, that they grow far too big for the average garden pool, and they have the typical carp appetite for underwater vegetation. The effect on oxygenating plants – and consequently on water clarity – is disastrous in small pools. They are really lake fish and I would certainly hesitate to introduce them into any pool smaller than a hundred square feet. Common and. Mirror Carp, too, with their propensity for rooting in the bottom like pigs, are quite unsuitable for the ornamental garden pool.
Native pond and river fish have no place in the garden pool either. Some, like pike and perch, are voracious eaters of other fish and with all of them there is the risk of bringing in various fish parasites and diseases. In any case, their natural protective coloration makes them practically invisible.
To my mind the greatest virtue in a pond fish is visibility: on this score good bright red goldfish and (except for very small pools) the lively surface-golden orfe are hard to beat. However, there is plenty of scope here for personal preference. You can visit a supplier and make your own choice, or pick from a number of mixed collections which he will offer, based on pool size. These will probably include one or two of the fish, usually tench, which have a reputation as useful scavengers. They are, but goldfish are equally industrious foragers on the bottom. The reputation of the tench as a doctor fish is pure myth and, since it is hardly ever seen once it is in the pool, and does nothing that cannot be done equally well by a goldfish, it is clear that its virtues have, to say the least, been exaggerated. Another frequently recommended scavenger, the catfish, should be kept out of the pool at all cost. It has a capacious mouth and a large appetite for other fish of any kind.
It is possible to buy selected pairs of’breeding fish’. This does not mean that they are on the point of spawning. Simply that they are guaranteed to be a male and a female, sexually mature and capable of breeding if the conditions are favourable. All that means, for the goldfish and its varieties, is a nourishing diet, -a well-planted pool, and warm summer temperatures. Orfe breed much less readily.
Unless you are impatient for quick results, the purchase of breeding pairs is not essential. Any mixture of small fish is almost bound to include both sexes and they reach sexual maturity very rapidly.
You will soon be aware when this has happened beeause you will see individual fish being nudged and chivvied by others. This apparently unkind treatment is the necessary attention of males to a female ripe for spawning and you will not be doing her a favour if you separate them. Thick plant growth in shallow water is the favourite situation for the deposit of eggs, and small planting containers filled with SOP and placed on the marginal shelf provide ideal conditions.
Collecting the spawn and rearing the fry separately is all very well if you are a dedicated and knowledgeable fish fancier; novices are not advised to try it. After all, if you reared two thousand young fish, what on earth would you do with them? Most pool owners will be satisfied to let nature take its course, which means the loss of many fry eaten by newts and other fish, and the survival of enough to stock the pool to the limit in the fullness of time.
The fry are so skilful at hiding in corners and among plant growth that it is usually some months. Even a full year, before their existence is noticed. They will be very slender but already bright with goldfish red or the mottled coloration of shubunkins. And some, almost certainly, will be a dull bronze. All the goldfish varieties have been developed by centuries of selective breeding from coloured sports of an originally bronzy species. In every generation there is likely to be a percentage of throwbacks to the dull-coloured ancestor, so the uncoloured fry need watching. It is quite possible for them to develop colour during their first two seasons. If they have not done so by the time they are 3 in. long they must be ruthlessly weeded out so that they cannot grow to breeding size and produce more and more uncoloured progeny.
The question that bothers pond owners more than anything else about fish is feeding – the question of how much and how often. They worry about it far too much. There is, in fact, no fixed amount of food that fish must have each day. Appetite and digestive ability vary with the water temperature and the amount of food needed is as changeable as the climate, as well as depending on the size of the fish. When fish are active, from spring to autumn, they can be fed daily, or, indeed, as often as they are prepared to take food. In colder weather the frequency of feeding is reduced to match their diminished appetites and in really cold conditions, when they are virtually in a state of torpor, do notat all. When a mild spell makes them lively and obviously keen for food, be ready to give it. It doesn’t take much practice to get the hang of judging what they need, and adjusting the amount accordingly.
I assume you will be giving them good nourishing stuff. Ants’ ‘eggs’ are useless nutritionally, while bread or biscuit meal, little better in this respect, can also cause digestive troubles. The most entertaining and hygienic way to feed fish is with floating pellets of high-protein food. Apart from being highly nutritious the pellets bring the fish to the surface where you can watch their antics. When they have had enough it is easy to spot and net off any of the pellets they have left, thus avoiding the danger that the surplus will decay on the bottom and foul the water.
Once a pool is well established and has abundant plant growth – which means also abundant insect life – feeding is not really necessary. Even so, it is a good idea to reinforce the natural food supply with pellets in the autumn, to get the fish in peak condition to face the winter, and again in the spring to help them recover quickly from their winter fast and to get them into breeding condition. If you are going ondon’t ask anyone to come in to feed the fish while you are away. They are almost sure to be wildly over-generous to be on the safe side and it is a quite unnecessary risk. A lot offish are killed by kindness, but I doubt if any ever starved to death if left to forage for themselves in a pool full of plants and the attendant insect life.