I062 BULLETIN OF THE BUREAU OF FISHERIES. 



Fishes that do exercise parental care differ as to the manner in which it is 

 shown and the length of time it is maintained. Most, if not all, of our centrarchids, 

 for instance, protect their eggs, but there is a difference between species or 

 genera otherwise. It was first declared some years ago (in 1903), by Prof. 

 Jacob Reighard, that the black bass continues the care begun with the nest 

 and new-laid eggs till the young fishes have acquired a considerable size, while 

 sunfishes of the genera Eupomotis and Lepomis discontinue care after the eggs 

 have been hatched. 



Undue generalization has been exercised also in statements respecting the 

 relative sizes of the sexes of fishes. A celebrated ichthyologist, in an "Intro- 

 duction to the Study of Fishes," positively declared that "it appears that in 

 all teleosteous fishes the female is larger than the male," and yet there are many 

 exceptions to this statement. Indeed, in most fishes whose males are differen- 

 tiated by marked secondary characters, so far as known the male is larger than 

 the female. Even in some of our common cyprinids such is the case; the species 

 of Semotilus, often miscalled "chub" or "horned dace," are examples. The 

 males of those species are stone-rollers, thereby preparing a nest for the eggs. 

 An undue generalization might be extended from the examples for it might 

 be assumed that there was coordination between the size and the care-taking 

 function. In contrast, however, the lumpsucker (Cyclopterus) confronts us; in 

 this case the male is much smaller than the female. In fact, we are in much 

 need of definite information as to relative sizes of fishes generally. 



A common African fish, the bolti {Tilapia nilotica) of Egypt, has males 

 larger than the females, and presumably many others of the same large family 

 do likewise. In this case the males prepare a nesting place but the females act 

 as nurses by taking their eggs into their mouths for incubation. 



There is a tendency among almost all men to too great generalization and 

 to an assumption that, because certain forms manifest special modes of behavior 

 or action, others do so also. Thus, because the fishes that had been noticed by 

 early observers did not take care of their eggs but left them after deposition 

 and fertilization to unaided nature, it was assumed that all fishes were alike 

 neglectful. Later, it was found that some forms did take charge of their eggs 

 and then it was assumed that it was the females, simply because among mammals 

 and birds the females do so. Our catfishes and sunfishes, for example, were 

 discovered to care for their eggs, but the old observers invariably credited 

 such care to the females. Meanwhile it was ascertained that it was really the 

 males, only or chiefly, that assumed such charge, and as such was found to be 

 the case also among the sticklebacks and various other fishes, the generalization 

 was conceived that in the case of all fishes that care for their eggs it was the 

 male that was the guardian. 



