6 ACANTHOPTERYGII. 



Breeding. In some ponds perch increase in numbers very rapidly : spawning 

 commences about the third year of the fish's life, when they have attained about 

 inches in length. The breeding season is from March to the commencement 

 of May, occurring even earlier in shallow water, while it is frequently continued 

 until June. They have been known to breed in aquaria, and Bloch describes 

 how they deposited their ova in long strings, in a glass vessel in which they 

 were kept in his room. Near Paris the number of females to males has been 

 given as 5 to 1, but stich has not been generally recorded elsewhere. Mr. Manley 

 however, in his " Notes on Pishing," states that 9 out of every 10 which an angler 

 takes are females : in fact the proportion between the two sexes appears to 

 vary in different localities. A fish of 1| lb. weight was found to contain 280,000 

 ova, but Lacepede, on the authority of Picot, gives nearly 1,000,000, however the 

 size of the example is not stated. Buckland recorded 127,240 in one 2 lb. 11 oz. 

 in weight, and 155,620 in one 31b. 2oz. The size of the parent is one factor to 

 be considered in computing the number of ova which seem to increase with the 

 age of the fish : the weight of the eggs has been known to equal one-fourth 

 of that of the entire fish. The eggs are about tbe size of poppy seeds, glued 

 together by mucus, into stringy bands or mesh-work, having much resemblance 

 to frog- spawn. The female selects a spot where rushes, reeds, or grass grow in 

 the water, or else seeks a piece of wood or some hard substance, against which she 

 rubs herself or presses, until one end of the glutinous band of ova has become 

 attached : then gently swimming away the eggs become voided. These ova being 

 readily observed are constantly being devoured by aquatic birds and other 

 enemies. In the Thames swans destroy fish spawn to a great extent. 



Their growth is slow, attaining to 2J inches in length at the end of the first 

 year, and about 5 inches at 2 years of age : but the rapidity of their growth 

 frequently depends upon local circumstances, especially as regards the purity or 

 otherwise of the water, the abundance or the reverse of suitable food, and whether 

 the locality is overstocked or not so. An example is recorded in which a perch 

 having lived five years in an aquarium only attained 8 inches in length and 

 then spawned. 



Hermaphrodite examples have been recorded by Yarrell.* 



Diseases. These fishes are occasionally subject to epidemics. Thus in 1867 

 a perch plague destroyed hundreds of thousands in the Lake of Geneva, caused 

 according to Dr. Forel and Dr. Du Plesis by the presence of certain minute fungi 

 in the blood. It has been stated in Yorkshire that " after a certain age they 

 become blind : a hard, thick, yellow fibre covers the whole surface of the eye, and 

 renders the sight totally obscured. When this is the case, the fish generally 

 are exceedingly black : and although from the more extreme toughness and 

 consistency of the membrane, it is evident that some have been much longer in 

 this state than others, yet there appears no difference either in their flavour or 

 condition. f Yarrell suggested that this opacity may be the effect of local inflam- 

 mation, produced by some of the numerous leech-like minute animals, which are 

 found to frequently occur in the aqueous humours of the eyes of fishes. 



Uses. The Laplanders, according to Linnaeus, employed the skin of this fish as 

 a strong glue for the purpose of joining together the two pieces of different sorts of 

 wood of which their bows were made. These skins were first dried, then soaked 

 in a little cold water in order that the scales might be easily rubbed off : several 

 of these skins were then enclosed in a bladder or piece of birch bark so that they 

 might not become moist : they were then placed in a pot of water to boil, a stone 

 being placed over the vessel in order to keep in the heat. Small perch are 

 frequently employed as bait for pike and trout. 



As food. This fish, especially when from rivers, has been held in great esteem 

 from the time of the Romans to the present day : in Ausonius's writings, when 

 recording delicacies for the table, he observes that the perch must not be omitted, 

 while among the fishes of the rivers, it is a worthy compeer to those of the sea, 

 and may even compete with the sea-mullet. Ray remarks that owing to its 



* British Fishes (Ed. 1), 1845, i, p. 91. 



f Thomas Huxley, Fish of Maltham Water, Craven, Yorkshire. 



