SUITABLE FISH AND SUITABLE WATERS
Having stocked his water with suitable vegetation and food, the next matter which should engage the attention of the amateur, is what fish he had better introduce. He should, where there is a fair chance of success, introduce a trout of some sort, as they give better sport than coarse fish.
The introduction of salmon into a river is not likely to be attempted by the amateur, but the head of salmon frequenting a river is undoubtedly affected in the most marvellous manner by artificial means. In Canada and the United States this is particularly remarkable, but the operations are conducted on a gigantic scale.
In the case of a stream or river where brown trout already exist, or have recently existed, in fair numbers, re-stock with these fish, for they can hardly be bettered in our waters. There are, however, some sluggish rivers where brown trout do not thrive when they are introduced. In such rivers and in many ponds in the South of England I believe that no better fish exists than the rainbow trout. I say particularly in the south, because I do not think that the rainbow trout will ever really thrive and breed in cold waters. I have at other times given numerous examples which go to show that the rainbow will only thrive in warm waters.[1] I will therefore only quote the case of New Zealand. The rainbow trout was introduced into both islands, but while it thrived amazingly in the warm waters of the North Island, it has proved a comparative failure in the cold waters of the South Island.
[1] The Rainbow Trout. Lawrence & Bullen, London.
While the common or brown trout (Salmo fario) and the rainbow trout (Salmo irideus) are, in my opinion, to be strongly encouraged in the waters suitable to their respective qualities, the American brook trout (Salvelinus fontinalis) does not seem to have met with the approval of most of the authorities on pisciculture in this country. My experience of this fish is not sufficient for my holding any very strong views with regard to its suitability to British waters. In one case I know that it was a great success for two seasons, but I have not had any opportunity of following it up in this particular instance. In another case it was a decided failure. I am sure that it should not be introduced into streams where brown trout thrive, and I am doubtful of its ever succeeding in waters which are suitable to the rainbow trout.
Of all the trout, the rainbow is the hardiest, and the one with which the amateur pisciculturist is most likely to be successful. It is also the fish most likely to supply a want felt by very many fishermen, a good sporting fish in waters where the common trout will not thrive.
In large and deep ponds with a good stream, or in lakes, char may be tried with a prospect of success. They require cold waters, and I have never heard of their being successfully introduced in the South of England. They are a more difficult fish to rear than trout.
Grayling have many violent opponents, but I am inclined to think that they do but little if any harm in a trout stream, and they supply excellent fishing during part of the close season for trout. They seem to thrive best in chalk streams, but there are no doubt many waters which would carry a good head of grayling which at present contain only trout. They probably do much less harm than most of the coarse fish constantly found in trout streams. The great crime attributed to them is that they eat the spawn of the trout, but I am inclined to think that the harm they do in this way is much over estimated. They spawn at a different time and would not be likely to frequent the spawning places at the same time as the trout. I have no doubt that an infinitely greater proportion of trout ova are eaten by the trout themselves than by grayling in rivers which contain both fish. Chalk streams and those rivers with gravelly bottoms and with alternate shallows and pools seem to be the most suited to the grayling.
Among coarse fish the rudd is one of the best from the fly-fisher's point of view. It takes the fly readily, is very prolific and very easy to introduce. It thrives remarkably well in ponds which contain a good supply of food. Its fry serve as excellent food for other fish, particularly trout, but I have known cases where it increased rapidly in a pond at the expense of the trout. It can, however, be kept under by judicious netting.