44 SALMONID^ OF BRITAIN. 



respiration*; while in some instances tlie gill-covers are abnormally small, leaving 

 a portion of the gills uncovered and consequently immersed in the sui-rounding 

 water, but more usually this seems to be the result of deficiency of development 

 or even of disease as gill-fever. 



Although alevins are able to subsist on the contents of their yelk-sac, so long- 

 as it lasts, it is imperative when this source of supply has become exhausted that 

 they should obtain natural or artificial nourishment, and now it is that most of 

 the monstrosities succumb, being generally unable to consume food, having been 

 up to this period in the same condition as chickens within their shells, prior to 

 being hatched. It is, however, very advisable to commence feeding alevins before 

 the yelk-sac has become quite absorbed, and as soon as the little fish appear to be 

 searching for nourishment themselves ; at this time they seem to require more air 

 and energetically push up stream. The food should consist of the finest particles, 

 while that which is tainted or diseased must be avoided as absolutely poisonous to 

 them. Opinions differ as to what is the most suitable nutriment, and difi"erent 

 fish-culturists advocate various constituents as being the best. Hard-boiled 

 eggs and fillet of horse are employed at Howietoun, six of the former, which had 

 been boiled twelve hours previously, to l lb. of the latter : or nine eggs to 1 lb. of 

 fillet, subsequently passed through pei'forated zinc of ISTo. 8 size, being a diameter 

 of 0'25 inch ; it has a long and stringy consistence, and many fish get hold of its 

 ends, as its thread-like bands are agitated in the water. Some emjiloy liver and 

 curd made from sour milk, in equal parts, or two portions of the former to one of 

 the latter, and all reduced to the finest particles : yolk of eggs boiled for half an 

 hour, and subsequently finely powdered : boiled liver by itself. Alevins will live 

 for a long time in water which is unchanged, and consequently can be transported 

 with comparative ease : they are likewise said to bear cold well. 



In some localities alevins are turned out into a stream or other suitable rearing 

 pond, protected from their enemies, while should they be put into an unprotected 

 piece of water they fall victims to all the vermin in the neighbourhood.f But 

 even if it is considered desirable to turn these alevins out such is not always 

 practicable, thus snow may be still present on the ground, and were it to suddenly 

 melt, floods injurious to these young fish might be occasioned. 



When the umbilical sac has become absorbed these fish commence to be known 

 as " fry," and now a period of greater danger to the artificially reared ones 

 commences. Looking more like fish, as they are no longer weighted down by the 

 large sac, they are seen to collect less in masses, in short, to lead more 

 separate existences, looking out for food. They rise from the floor of the 



employed them for this purpose. Alevins of the trout 0-85 in. long, and also a salmon 1-25 in. long, 

 of about the same age, were placed in a tumbler of still water taken from the tray where it stood 

 at 4'2° Fahr., at 11-7 a.m., and which, on being carried indoors, rose by 11-20 a.m. to 45°. In 

 seven minutes the pectorals of the trout began to be used for accessory breathing purposes, at the 

 rate of three times to every once of the gill-covers ; this went on for fifteen minutes, when the 

 fish was returned to the tray. The salmon alevin breathed faster, but did not employ its pectoral 

 fins. 



* In 1884 some little blennies, mostly shannies, Blennius (jattoruginc, were placed in a small 

 salt-water aquarium, the contents of which had been accidentally left unchanged, and the water 

 as a consequence had become very foul. The little fish until the water was changed could be 

 seen emi^loying the uj^per rays of their pectoral fins in order to assist respiration, for in these 

 fishes the character of the rays differ, the upper seven being shorter, thinner, and more elastic 

 than the lower six, which are thicker and stiffer. Although the entire thirteen may be employed 

 simultaneously during locomotion, the uj^per ones, when the fish is stationary, may be used to 

 assist breathing, while the lower stiff ones are employed to support. In gobies the ventral fin 

 under the same conditions was observed to be used in order to attach the fish to the aquariurn, 

 while the outer pectoral rays were also placed against the glass, as a person during an asthmatic 

 paroxysm fixes his elbows on the table or window-sill while he gasps for breath. During this 

 period the gill-covers were spasmodically working at about 108 times in a minute. 



t Andrews, Badminton Libmrij, " Salmon and Trout Culture," page 435, observed that 

 " most fishing clubs not being able to provide suitable rearing-places for their young fish turn 

 the ' fry ' that they produce or breed direct into the rivers, which already contain trout, the 

 probable consequence being that 91) out of every 100 go down the throats of the larger fish .... 

 a few hundred yearling fish would cost far less and make a much better ' show ' in the water." 



