Vol. XXXVIII. January, 1920. No. i. 



BIOLOGICAL BULLETIN 



THE BREEDING BEHAVIOR OF THE SUCKERS AND 



MINNOWS. 



I. THE SUCKERS. 1 







JACOB REIGHARD. 



CONTENTS. 



I. Introduction to the Series i 



II. Breeding Behavior of the Suckers 3 



A. The White Sucker 3 



1. The Breeding Grounds and Breeding Season : . 3 



2. General Activities of Breeding Fish . 4 



3. Coloration and Color Changes 6 



4. Sexual Differences 6 



Color 6 



Pearl Organs 7 



Fin Length 8 



5. Breeding Activities 9 



B. The Common Red-horse 15 



1. Breeding Grounds and Breeding Season 15 



2. Sexual Differences 16 



3. Coloration 18 



4. Breeding Activities 19 



C. The Hogsucker 20 



1. General Activities 20 



2. Sexual Differences 21 



3. Breeding Activities 22 



III. Summary of Observations. 



A . The White Sucker .... 24 



B. The Red-horse 26 



C. The Hogsucker 28 



IV. Conclusions 29 



V. Literature 31 



i. INTRODUCTION TO THE SERIES. 



This paper is the first of a series on the breeding habits of 

 nine species of suckers and minnows. These fishes form a well- 

 defined group by some systematists united into a single family, 



1 Contributions from the Zoological Laboratory of the University of Michigan. 



I 



