FISH: ALL YOU EVER WANTED TO KNOW (BUT WERE AFRAID TO ASK) Anatomy 1. Poikilothermic: body temperature approximates surrounding water temperature; in general fish can live in water below zero to geothermal hot springs--but each species has a much narrower range; gradual changes can be adapted to 2. Skin: No keratin layer; covered by mucus, fatty acids, etc. Scales: Ctenoid = elasmobranchs (sharks, skates-cartilage) Cycloid = teleost fish (bony-smooth outer surface) 3. Respiratory: low available oxygen content in water compared to air (air has 26x times as much oxygen as same volume of water at the same temperature)--thus fish expend more energy in respiration than most mammals--thus are "sprinters" with high amt of white muscle because they can function for a short time anaerobically. Respiration rate controlled via O2 receptors in first gill arch; Root Effect: (only in teleost) at increased pH (gills) oxygenation 4x faster than deoxygenation but at low pH (tissue/muscle) de-ox 400x faster than oxy-nate Counter current flow of water over gills. 4. Circulatory: 2-chamber heart; blood flow: ventricle - bulbus arteriosus - ventral aorta - afferent branchial arteries (gills) - efferent branchial arteries - dorsal aorta. Bottom line: heart mm receives most poorly oxygenated blood and retina receives most richly oxygenated blood 5. Urinary: kidney is major site of hematopoiesis. This tissue is between nephrons in the posterior ("trunk") kidney and is the most prominent feature in anterior ("head") kidney. Kidney (teleosts) not sole or primary osmoregulatory/waste organ. Most NH3/NH4 excreted through gill epithelium and the chloride cells of teh gills, operculum, and buccal cavity are primary means of osmoregulation. 6. R-E System: No lymph nodes. Pigmented macrophages in groups (melanomacrophage centers) present in spleen, kidney & liver. Teleosts can produce specific Igs, elicit cell-mediated immunity, show delayed and immediate hypersensitivity and immune memory; produce only IgM. 7. Digestive: Teeth in phayrnx and mouth; anchored in bone. Taste buds down into esophagus; pancreas diffuse, liver less structured - little lobulation - some hepatopancreas. Swim Bladder is outpouch of GI tract--adjusts specific gravity which decreases energy expended to maintain set depth. 8. Endocrine: No parathyroid - Calcitonin (hypocalcemic) produced in ultimobranchial body near esophagus. Corticosteroids made in "head" kidney near cardinal veins. Urophysis near distal end of spinal cord produces peptides (urotensins) involved in osmoregulation (change in water salinity creates change in urotension production) 9. Acousticolateralis System: ear receives acoustic stimuli and changes in angular acceleration. Lateral line receives changes in hydrostatic stimuli 10. Diet: growing fish need 50% protein in diet; Salmon (Coho), Rainbow Trout, & others have absolute requirement for Vitamin C. Point: each fish has different requirements. 11. Amazon Molly (Poecilia formosa) is all female species (gynogenesis). Sperm of closely related species stimulates the development of ova but do not contribute to the genetic lmakeup of the young; all are clones. 12. Behavior: fish are most sensitive to smells. Pheromones have major influences. Schooling thought to be pheromone + sight controlled. Alarm Substance is pheromone produced in "club cells" in the skin, released following trauma--causes flight of other fish of the same species from the injured fish. 13. Paired fins = pectoral, pelvic; Unpaired = dorsal, adipose, caudal (tail), anal. Diseases 1. Channel Catfish Virus (CCV) - Herpesvirus; a lymphocystis- like disease - warty growths. (Lymphocystis = Poxvirus). 2. Infectious Hematopoietic Necrosis (IHN) - Rhabdovirus; rainbow trout fry and fingerlings. 3. Infectious Pancreatic Necrosis (IPN) - Aeromonas salmonicida, Pseudomonas fluorescens. 4. Ichthyophthirus multifilis - "ich" - white spot disease-- trophozoite (parasite) is on the fish therefore changing water will not cure. 5. Anisakis - anisiakiasis in man, nematode of herring. Rowfish form eosinophilic granulomata of stomach and intestine--also man. 6. Aflatoxin - metabolite of Aspergillus flavus; Salmonids are very sensitive. 7. Fish cannot methylate mercury; methyl mercury is toxic. 8. Aspergillus flexibacterium - "cotton wool disease" or "mouth fungus" (Columnaris Disease); see boils and ulcers. 9. Myxosoma cerebralis - protozoa that causes "Whirling Disease"; this is reportable. Anesthesia 1. MS-222 = ethyl m-amino-benzoate sulfanate/tricaine methylsulfonate. 2. Quinaldine sulfate 3. Alka Seltzer (CO2) 4. Saffan (alphaxalone)