PREFACE THE USE OF FISHES as experimental animals has contributed much to our knowledge in many phases of animal science. Nigrelli 1953 has reviewed some of the more outstanding of these contributions. The principal obstacle connected with the use of fishes as ex- perimental animals is the lack of information on the selection and maintenance of experimental fishes. This apparent need has prompted the author to attempt to bring together some of the more important considera- tions associatedwith this problem. Notable among these considerations are nutrition, disease, and the artificial maintenance of suitable environmental conditions. This work is limited to a treatment of freshwater fishes and is based upon the authors experience in this area of interest and upon such literature as seems relevant. There are some considerations concerning the maintenance of captive fishes about which there is little information available. It is hoped that research persons will be stimulated to make contributions on these topics....