FISH-PONDS. CXI 



pond it sbould not be too deep, shallows being necessary for the fry which 

 rarely go into deep water, which being colder in the summer than the shallows 

 is less frequented by insects. Trees in their vicinity are detrimental because- 

 the leaves falling into the water occasion the formation of a black mud, and 

 the escape of foetid gases, which in winter, especially when the water is 

 covered with ice, become very injurious to the fish. Rank vegetation along 

 the banks is often injurious, although- some' weeds when present afford 

 shelter and assist in clearing the water. 



There should always be facilities for running a fish-pond dry, and the 

 • same depth of water should be maintained throughout the year. The inflow 

 of water should never be direct from a brook but conducted from one side, 

 and the sluices should be strong enough to render overflow impossible, while 

 there should be a grating to keep out strange fish. The centre of the pond 

 should be deeper than the rest, while near the outlet should be a spot still 

 deeper than any other part of the pond. 



The number and sorts of fish suitable for stocking ponds depends on 

 many circumstances, especially as regards the food which is present, whether 

 the "water comes from a stream or from springs,, and many other conditions. 

 Boccius recommends the following as suitable for an acre of water : . 200 

 brood carp, 20 brood tench, and 20 brood pike. North cautions the fish- 

 culturist against over-stocking and recommends that after the first year they 

 should be diminished because the food will decrease. When a pond is dried 

 the contained 'fish should be examined as to whether they are in good or bad 

 condition, from which it must be judged whether the water has been 

 under- or over-stocked. 



In 1754, Mr. Tull communicated a paper to the Royal Society respecting 

 how he had castrated certain carps,- and asserting that their flavour had 

 become much improved consequent upon the operation. 



Salt-water vivaria have been tried with varying success, and one would 

 imagine that .with care and attention they might be made suitable for the 

 reception of some marine forms as bass, mullet, &c., so that a constant supply 

 to the market would be available even at the periods when gales hinder the 

 sea-fisherman's occupation. These vivaria may be placed on the coast and 

 either be entirely supplied with salt-water by means of tidal influence, or may 

 be lakes wherein the lower portion consists of salt or brackish water and the 

 upper of fresh, where it may be fed by a stream. The locality selected, 

 irrespective of all advantage of situation, should be where the necessary 

 food could be obtained at a cheap rate, whether such is the refuse of fish, 

 meat offal, shell-fish, or manufactured substances. Also, should the local 

 demand for fish be insufficient there ought to be the means of inexpensive 

 and easy carriage to a suitable market. Several such vivaria have been formed 

 at different places around these islands at various times ; Parnell mentions 



