Ichthyology describes all aspects of fish from their classification, behavior, diversity, ecology, habits and uses. In the present book the whole subject matter has been divided into thirty chapters which includes introduction, classification, agnatha, class cyclostomes, super class gnathostomata, class elasmobranhi, subclass bradyodonti,classosteichtyes, subclass crossopterygii, order dipnoi, body shape and size, tegument, scales, colouration, fin, muscles and locomotion, skeletal system, food and feeding habits and alimentary canal, respiratory system, blood vascular system, swim bladder, weberian ossicles, nervous system, endocrine organ, exrecretory system, reproductive system, parental care, fish migration, special characters and adaptation in fishes.This textbook is primarily intended as a textbook for UG and PG courses of zoology, aquaculture and fisheries of Indian Universities. This publication would fulfill the needs of students, teachers, researchers, extension workers, zoologists, aquaculturists, technocrats, limnologists, aquatic ecologists, fisheries and marine biologists as well as by those who are engaged in commercial exploration of aquaculture and fisheries. Contents: Preface vii 1. Introduction 1 2. Classification 5 3. Super Class: Agnatha (Ostracoderms and Cyclostomes) 13 4. Super Class: Agnatha–Living Agnathans, Cyclostomata 21 5. Super Class: Gnathostomata 51 6. Class: Elasmobranchii 59 7. Sub Class: Bradyodonti 105 8. Class: Osteichthyes 117 9. Sub Class: Crossopterygii 189 10. Order: Dipnoi 199 11. Body Shape, Size and some Salient Features 219 12. Tegument 227 13. Scales 233 14. Colouration 245 15. Fins 251 16. Muscles and Locomotion 265 17. Skeletal System 275 18. Food, Feeding Habits and Alimentary Canal 297 19. Respiratory System 317 20. Blood Vascular System 337 21. Swim Bladder 361 22. Weberian Ossicles 375 23. Nervous System 387 24. Sense Organs 405 25. Endocrine System 439 26. Excretory System and Osmoregulation 455 27. Reproductive System and Development 469 28. Parental Care 489 29. Fish Migration 499 30. Special Features 509 Index 547