TROUT. THE MANAGEMENT OF THE FRY (Continued)

In the last chapter I brought my reader up to the point where the fry, which had been feeding for some time in the rearing boxes, had been judiciously separated, the weaker and smaller fish which took up their positions at the lower ends of the boxes having been put into separate boxes and induced as much as possible to keep at the head near to where the current enters.

It is difficult to lay down any certain rule as to what is the best time at which to take the next step that of turning the fry out into the rearing ponds. When the fry have got into more or less regular habits, and showing no fear of whoever it is who feeds them, come up readily and seize the food boldly, is probably the best time to let them out into the larger space of the pond. I do not mean to say that when a certain proportion of the fish have got over their natural shyness, and feed boldly and without hesitation, the whole of them should be set free. What I mean is, that when the habit of associating the appearance of a certain individual with a meal has been well established among them for a week or so, they should be allowed to escape from the box into the pond.

This is best done in the same way that the alevins were allowed to escape from the hatching tray into the box by lowering the level of the box so that its upper edges are some two or three inches below the surface of the water. The food should now be thrown into the pond higher up, so that the little fish may be induced to swim up and station themselves as near the inlet as possible. Probably some of the little fish will not leave the box at all of their own free will. These, of course, will have to be turned out. The box should not, however, be lifted out of the water and the fish and water together be poured out, as this is very likely to cause them severe injury. The box should be gradually tilted over and lifted out of the water bottom first, so that the fish are hardly disturbed at all and certainly not injured in any way.

An important matter to consider before turning the little fish out into the pond is, how the ponds are to be protected so that their many enemies may be kept away from the fry. Kingfishers, herons, and other creatures are very partial to young trout and will cause enormous destruction if not prevented. Kingfishers have, in my experience, been the worst offenders. Some years ago I was rearing some trout in a part of the country where many of the inhabitants bewailed the extermination of the kingfisher. Before I began rearing trout I agreed with these people, for a kingfisher flitting along a stream looking like a little mass of jewels is a pleasing sight, and one which I had never enjoyed in that particular part of the country.

When the time came to set my little fish free in the rearing ponds, as a matter of principle I covered the ponds with herring-net, closely pegged down on the banks so that I could not even get my hand under the edge. I did not think that there were any kingfishers or herons about, and so was very surprised when one morning, on going down to feed the fish, I found a kingfisher under the net, flying up and down the pond trying to get out. By carefully introducing a landing-net under the netting over the pond, I was able to catch the intruder, and caught four more in the same way in about three weeks. Since that time I have not agreed with the people who have stated that the kingfisher is almost extinct, at least in that part of the country. I may say that there are but few streams there, and that it is not at all an apparently likely place for kingfishers. I am quite sure that wherever any one begins to rear fish there he will find that kingfishers are fairly common. The amateur will probably be also surprised at the way herons appear, if he conducts his fish-rearing operations, as he should do, in a secluded spot.

Many of the directions I gave as to the management of the fry and the rearing boxes, apply also to the fry after they have been turned out into the ponds. The doses of earth should still be given regularly, and salt may be applied also in the way I have already described. The little fish will be found to scatter over the pond or to divide again into two bodies, one at the upper and one at the lower end of the pond, as they did in the boxes. The fish culturist should try to induce these fish to come to the head of the pond as much as possible. It is a good thing to place some boards across the head of the pond to give shade and shelter to the fry. It will probably be found that if much artificial food is given to the little fish, a scum will be formed on the surface of the water. This scum is composed of grease, and should be removed, as soon as it is observed, with a gauze net.

All the time that these operations have been going on with regard to the little fish themselves, due attention should have been given to the vegetation round the ponds. The alders and willows which I before recommended to be planted round the ponds should be induced as much as possible to overhang the water. Grass and other vegetation should be allowed to grow freely round the margins, as many insects are then likely to fall into the water.

This vegetation will supply the little fish with a certain amount of natural floating food, without any interference on the part of the fish culturist; but he should, however, give them other floating food, both natural and artificial, as much as possible, for this will get them in their youth to adopt the habit of feeding freely at the surface. When the alders and willows have grown sufficiently and are well covered with leaves, they will probably give enough shelter to the fish to make the boards at the upper end of the pond unnecessary.

As time goes on, and the little fish grow, they should be thinned out, the smaller and weaker being removed into another pond. Despite the best endeavours of the fish culturist, a certain number of these small fish are sure to keep to the lower end of the pond, and it is these which should be removed first. If they are left, the difference in size between the smaller and the larger will soon become so great that the large fish will very likely be tempted to eat the small ones, thus developing a cannibalistic habit which they will keep always.

At the end of August or the beginning of September the little fish will have got over the most dangerous part of their lives. After this time they are called yearlings, are much more hardy and not subject to nearly as many risks as up to that time.

The great points to remember are: That the food should be varied as much as possible; and as much natural food, of a hard description such as shrimps, corixae, snails, bivalves, etc., be given. That the little fish should be well protected from enemies. That they should not be over-crowded, but the weakly and small fish be separated from the larger fish. That frequent doses of earth should be given to keep the bottom sweet and clean. That the inlets and outlets should be frequently cleaned and kept clear, to ensure a good flow of water through the ponds, and that a careful watch should be kept for such misfortunes as fungus and dead fish, in order that they may be dealt with at once.