222 A HISTORY OF FISHES 



have been shown to be associated with such emotions as greed, 

 anger, or fear. Although in ourselves a feeling of extreme 

 fear is followed by pallor, in fishes the experience of this emotion 

 is generally followed by the assumption of a dark coloration. 



Very remarkable colour changes often occur after death, 

 and the hues of many fishes a few hours after capture are quite 

 different to those exhibited in life. In Mackerels [Scomber)^ 

 Mullets (Mullidae) and other brightly iridescent forms, the 

 colours appear to be brightest at the time intervening between 

 the capture of the fishes and their death, and in Roman times 

 Red Mullet were not infrequently brought alive to the ban- 

 queting table, swimming round and round in a glass vessel, so 

 that the guests might gaze on the brilliant display of colour 

 changes afforded in their death struggles. So esteemed were 

 these fishes for their vivid hues and exquisite flavour that at 

 the height of the Roman Empire fabulous sums were paid 

 for particularly fine specimens. Suetonius mentions three 

 fish for which, roughly, ^£"240 was paid, and a single individual 

 in the reign of Claudius is said to have fetched more than £^0. 



There are, of course, other functions of coloration besides 

 concealment. The question of recognition marks has already 

 been touched upon {cf. p. 154), and it is difficult to find any 

 other explanation of the sudden switching on, for example, of a 

 row of black or white spots along the side of the body. Many 

 species exhibit peculiar markings which are remarkably constant 

 in all the individuals — a spot below or behind the eye, a stripe 

 from eye to mouth or at the angle of the mouth, a blotch on 

 the gill-cover, a bright red fin, a brilliant margin to dorsal, 

 anal, or caudal fins, a purple or emerald spot in the axil of the 

 pectoral or pelvic, or a brilliant eye-like spot often ringed 

 with white or yellow on a particular part of the body or fins. 

 Any explanation of these as recognition marks is naturally 

 hypothetical, but the theory that such marks are intended to 

 aid the individuals of a species to recognise one another is quite 

 as plausible as that which assigns this purpose to certain patches 

 of coloured feathers in birds or similar specific markings in 

 mammals. 



The young of some species are conspicuously differently 

 coloured to the adults, and although in some cases this may be 

 shown to go hand in hand with a corresponding difference in 

 habits or environment, and is undoubtedly protective, in others 

 no such connection seems to exist. The characteristic "parr- 

 marks" of a young Salmon or Trout, which disappear altogether 



