Fish Disease

Edward J. Noga, MS, DVM, is Professor of Aquatic Medicine (College of Veterinary Medicine) and Adjunct Professor of Zoology (College of Agriculture and Life Science) at North Carolina State University, in Raleigh, North Carolina, and Adjunct Professor of Marine Science (Center for Marine Science) at the University of North Carolina in Wilmington, North Carolina.

Preface to the First Edition ix

Preface to the Second Edition xi

Acknowledgments xiii

How to Use the Book xv

Part I Methods for Diagnosing Fish Diseases

1. Major Cultured Species 5

Aquarium (Pet) Fish 5

Bait Fish 7

Food Fish 7

Laboratory Fish 8

2. Types of Culture Systems 9

Closed Culture Systems: Aquaria 9

Closed Culture Systems: Ponds 10

Flow-Through Culture Systems 11

Semi-Open Culture Systems 12

3. The Clinical Workup 13

Equipping a Fish Disease Diagnostic Facility 13

Case Submissions 13

Water-Quality Analysis 16

Taking the History 17

The Physical Exam 17

Clinical Techniques: Routine Methods 20

Clinical Techniques: Specialized Methods 35

4. Postmortem Techniques 49

Euthanasia 49

Preserving Parasites 49

Culturing for Bacteria 49

Sampling for Water Molds and Fungi 55

Sampling for Viruses 55

Examining Tissues Postmortem 55

Zoonotic Diseases and Other Human Pathogens 63

5. Guidelines for Interpreting Clinical Findings 65

Environment, Stress, and Fish Disease 65

Acclimation 65

How to Use Part II, the Problem List 65

Sample Problem Data Sheet 66

Clinical Decision Making: Have the Major Problems Been Identified? 67

Prioritizing Problems 68

Treatment Plans 68

When to Refer Cases 68

6. Health Management 69

Biosecurity 69

Health Promotion and Maintenance 73

Animal Welfare 77

Food Safety 78

Environmental Safety 78

Part II Problem List

7. Problems 1 through 10: Diagnoses made with commercially available water-quality test kits or equipment that should be present in the clinician’s clinic 83

1. Environmental hypoxia 83

2. Temperature stress 88

3. Temperature stratification 90

4. Ammonia poisoning 91

5. Nitrite poisoning 96

6. Nitrate poisoning 98

7. Too low (too acidic) pH 100

8. Too high (too alkaline) pH 102

9. Improper hardness 103

10. Improper salinity 104

8. Problems 11 through 43: Diagnoses made by either gross external examination of fish, wet mounts of skin/gills, or histopathology of skin/ gills 107

11. Gas supersaturation 107

12. Lamprey infestation 109

13. Leech infestation 110

14. Copepod infestation/infection 112

15. Branchiuran infestation 119

16. Isopod infestation 121

17. Monogenean infestation 123

18. Turbellarian infection 129

19. Protozoan ectoparasites: general features 129

20. Ich infection 131

21. Marine white spot disease 135

22. Trichodinosis 137

23. Chilodonella infestation 138

24. Brooklynella infestation 139

25. Tetrahymenosis 140

26. Scuticociliatosis 141

27. Marine velvet disease 143

28. Freshwater velvet disease 147

29. Ichthyobodosis 148

30. Gill Cryptobia infestation 150

31. Gill amoebic infestation 150

32. Sessile, solitary, ectocommensal ciliate infestation 153

33. Sessile, colonial, ectocommensal ciliate infestation 155

34. Typical water mold infection 156

35. Epizootic ulcerative syndrome 162

36. Branchiomycosis 164

37. Columnaris infection 166

38. Bacterial cold water disease 169

39. Bacterial gill disease 170

40. Lymphocystis 171

41. Epitheliocystis 172

42. Miscellaneous skin and gill diseases 174

43. Incidental findings 176

9. Problem 44: Diagnoses made by examination of a gill clip or a blood smear 179

44. Primary hemopathies 179

10. Problems 45 through 57: Diagnoses made by bacterial culture of the kidney or affected organs 183

45. Bacterial dermatopathies/systemic bacterial infections: general features 183

46. Motile aeromonad infection 185

47. Aeromonas salmonicida infection 186

48. Enteric septicemia of catfish 190

49. Edwardsiella tarda infection 192

50. Vibriosis 193

51. Pasteurellosis 196

52. Enteric redmouth disease 197

53. Streptococcosis 199

54. Bacterial kidney disease 201

55. Mycobacteriosis 204

56. Piscirickettsiosis 208

57. Miscellaneous systemic bacterial infections 210

11. Problems 58 through 76: Diagnoses made by necropsy of the viscera and examination of wet mounts or histopathology of internal organs 215

58. Digenean trematode infection: general features 215

59. Digenean gill infection 220

60. Nematode infection 222

61. Cestode infection 226

62. Acanthocephalan infection 229

63. Myxozoan infection: general features 229

64. Proliferative gill disease 236

65. Ceratomyxa shasta infection 237

66. Hoferellus carassii infection 239

67. Proliferative kidney disease 239

68. Whirling disease 242

69. Miscellaneous important myxozoan infections 243

70. Microsporidian infection 247

71. Ichthyophonosis 253

72. True fungal infections 254

73. Diplomonad flagellate infection 257

74. Tissue coccidiosis 258

75. Miscellaneous endoparasitic infections 264

76. Idiopathic epidermal proliferation/neoplasia 264

12. Problems 77 through 88: Rule-out diagnoses 1 (viral infections): Presumptive diagnosis is based on the absence of other etiologies combined with a diagnostically appropriate history, clinical signs, and/or pathology. Definitive diagnosis is based on presumptive diagnosis combined with confirmation of viral presence (e.g., antibody probe, gene probe), 269

77. Systemic viral diseases: general features 269

78. Channel catfi sh virus disease 270

79. Infectious pancreatic necrosis and other aquatic birnaviruses 271

80. Infectious hematopoietic necrosis 274

81. Viral hemorrhagic septicemia 278

82. Infectious salmon anemia 282

83. Spring viremia of carp 285

84. Iridoviral diseases 287

85. Nodaviral diseases 289

86. Koi herpesvirus disease 292

87. Alphavirus diseases 294

88. Miscellaneous systemic viral diseases and infections 298

13. Problems 89 through 99: Rule-out diagnoses 2: Presumptive diagnosis is based on the absence of other etiologies combined with a diagnostically appropriate history, clinical signs, and/or pathology. Definitive diagnosis is based on presumptive evidence combined with further, more extensive workup with a specific identification of the problem 305

89. Nutritional deficiency 305

90. Hypercarbia 309

91. Hydrogen sulfide poisoning 309

92. Chlorine/chloramine poisoning 310

93. Metal poisoning 311

94. Cyanide poisoning 314

95. Miscellaneous water-borne poisonings 315

96. Harmful algal blooms, 321

97. Acute ulceration response/environmental shock/delayed mortality syndrome 325

98. Traumatic lesions 326

99. Genetic anomalies 330

14. Problems 100 through 102: Rule-out diagnoses 3: Presumptive diagnosis is based on the absence of other etiologies combined with a diagnostically appropriate history, clinical signs, and/or pathology. Definitive diagnosis is not possible since the etiology is unknown (idiopathic) 333

100. Lateral line depigmentation 333

101. Senescence 336

102. Miscellaneous important idiopathic diseases 336

15. Problem 103: Diagnoses made by examination of eggs 341

103. Egg diseases 341

Part III Methods for Treating Fish Diseases

16. General Concepts in Therapy 347

Treatment Guidelines 347

Routes of Drug Administration 358

Recommended Treatments in Various Culture Systems 371

Which Dosage to Use 373

17. Pharmacopoeia 375

Acetic Acid 376

Acriflavin 376

Activated Carbon 376

Agricultural Lime 376

Alum 376

Anesthetics 376

Antibiotics 377

Amoxycillin Trihydrate 378

Ampicillin Sodium 378

Chloramphenicol 378

Enrofloxacin 378

Erythromycin 379

Florfenicol 379

Flumequine 380

Furaltadone 380

Furazolidone 380

Kanamycin Sulfate 380

Nalidixic Acid 380

Neomycin Sulfate 381

Nifurpirinol 381

Nitrofurazone 381

Oxolinic Acid 381

Oxytetracycline 382

Sarafloxacin 383

Sulfadiazine-Trimethoprim 383

Sulfadimethoxine-Ormetoprim 384

Sulfadimidine-Trimethoprim 384

Sulfamerazine 384

Sulfamethoxazole-Trimethoprim 384

Antiseptics 384

Bayluscide® 385

Benzocaine 385

Biological Control 385

Bithionol 385

Bronopol 385

Buffers: Freshwater Aquaria 386

Buffers: Marine Aquaria 386

Buffers: Ponds 386

Butorphanol 387

Calcium 387

Carbon Dioxide 387

Chloramine Neutralizer 388

Chloramine-T 388

Chlorhexidine 389

Chloride 389

Chlorine 389

Chlorine Neutralizer 390

Chloroquine Diphosphate 390

Chorionic Gonadotropin 391

Clove Oil 391

Copper 391

Chelated Copper 391

Copper Sulfate 392

Deionized Water 393

Diflubenzuron 393

Dimetridazole 394

Diquat 394

Disinfection 394

Electroshock 396

Enamectin Benzoate 396

Eugenol 397

Euthanasia 397

Fenbendazole 398

Flubendazole 399

Formalin 399

Formalin/Malachite Green 400

Freshwater 400

Fumagillin 401

Gonadotropin Releasing Hormone 401

Hydrogen Peroxide 401

Hyposalinity 402

Hypothermia 403

Immunostimulants 403

Ivermectin 404

Ketamine 404

Ketoprofen 404

Levamisole Hydrochloride 404

Lidocaine 404

Magnesium Sulfate 404

Malachite Green 405

Mebendazole 406

Methylene Blue 406

Methyltestosterone 406

Metomidate 407

Metronidazole 407

Monensin Sodium 407

Nitrifying Bacteria 407

Organophosphate 408

Ozone 409

Peat 410

2-Phenoxyethanol 410

Piperazine Sulfate 410

Potassium Permanganate 410

Povidone Iodine 411

Praziquantel 412

Pyrethroid 413

Quaternary Ammonium Compounds 413

Quinaldine Sulfate 414

Salt 414

Secnidazole 415

Sedatives 415

Silver Sulfadiazine 415

Slaked Lime 415

Sodium Bicarbonate 416

Sodium Pentobarbital 416

Sodium Phosphate 417

Sodium Sulfi te 417

Teflubenzuron 417

TFM 417

Toltrazuril 417

Tonic Immobility 417

Tricaine 417

Triclabendazole 418

Ultraviolet Light 418

Unslaked Lime 419

Vaccines 419

Virkon® Aquatic 419

Water Change 419

Wound Sealant 420

Zeolite 420

Literature Cited 421

Appendix I Fish Disease Diagnosis Form 471

Appendix II Suppliers 473

Appendix III Scientific Names of Fish Mentioned in the Text 481

Appendix IV Definitions of Terms 491

Appendix V Example Form for Shipping Fish to a Clinic or Diagnostic Laboratory 495

Index 497