Exotics - Fish 2

pbhati17's version from 2017-03-08 16:43

Water Quality

Question Answer
*Most fish are ectotherms. What does that mean? Which fish can regulate temperature to some extent? How?Ectotherms = Same temp as environment
Tuna can regulate via eye heater
*For every rise of 10⁰ C, what happens to the metabolic rate?Doubles
*Fish farmers will put what stage of fish into warmer water to speed production? What happens if the water gets too warm?Fish farmers will incubate eggs/fry in warmer water
If too warm, see spinal/cardiac deformities
*Which do fish tolerate better, a rise in temperature or a drop? What is associated w/ a rise in temperature?Fish tolerate a drop in temperature much better. ↑ temperatures affect the immune system (T helper cells), so fish are more susceptible to bacterial dzs
*What can happen to fish if temperatures dip too ↓?Winter kill
What do rising temperatures do to respiratory rate? What does that mean for exposure to water pollutants?Rising temp = ↑
Resp rate = ↓ survival in polluted water bc ↑ exposure
What is the term for a stratification of water, where at certain times of layers can invert → poor water quality to the top & killing fish in cages?Thermoclines
*What is Respiratory Distress Syndrome? What should you do to treat this?Respiratory Distress Syndrome: Unable to extract enough O2 for needs. Need to reduce feed & unnecessary movement to conserve O2/reduce O2 demand
What are some accessory breathing capabilities (other than gills) that allow some spp to survive at extremely ↓ O2 levels?Skin
Swim bladdar
Which have ↑er O2 needs - big or small fish? Therefore, which fish should be put into the “head”? What does this mean?Small fish require more O2, so young fish should be put into the “head”, aka best quality water (NOT the toilet!)
What do ↑ fecal levels/detritus do to the available O2? What is the term?Consume O2 - aka Biological O2 Demand (BOD)
*What 2 factors reduce the solubility of gas in water?(1) ↑ temperature (remember bc gases are liquid at ↓ temps, so you can have more gas in the water when it’s cold)
(2) ↓ pressure (think of pressure as pushing gases into solution, so reducing pressure reduces the amt of gas entering)
(think about soda, we keep soda under pressure and in the fridge to keep the the CO2 in solution!)
*What does ↑ temperature & ↓ pressure cz?Supersaturation = Gas Bubble Dz! It czs all the gases in the fluids inside fish to come out of the fluids!
*What are some common ways people kill their fish w/ this phenomenon?Buying supersaturated water (perrier)
Leaks in pumps (venture effect)
↑ sunshine (photosynthesis)
New aquarium filled from the ↑ pressure of the tap
Taking water from ↑ pressure source (like the bottom of a dam)
What are the 2 types of suspended solids? Which is more of a problem?Organic (ex. feed) = more of a problem
Non-organic (ex. clay) = little problem, even at ↑ levels
*What is the equation relating ammonia/ammonium to water temperature & pressure? Which 1 is more dangerous? ↓ pH moves the equation which way? ↑er water temps move the equation which way?NH3 (ammonia/dangerous) + H2O ↔ NH4 (ammonium) + OH
↓ pH & ↓ temperatures move equation to the right = good
↑ pH & ↑ temperature move the equation to the left = bad
*Which form of ammonia is secreted by the gills? What ion exerts a protective effect in seawater?Gills secrete NH3, Ca2+ is protective


Question Answer
*What happens when we put the rainbow trout in w/ ammonia for 3 months? Does it dmg the gills directly?Coma for 3 weeks (liver brain!), then recovery. No direct affect on gills
*What are the breakdown products of ammonium (NH4)? What breaks it down? What is it called?Ammonium → nitrite by nitrosomonas, nitrite → nitrate by nitrobacter
Called Nitrification
*Which 1 is slower to establish? Therefore, what may build up in new tanks?Nitrobacter is slower to establish → nitrite buildup in new tanks
*What does nitrite combine w/ that makes it dangerous? What is the result/fatal dz? Is this a problem in salt or fresh water?Nitrite + hemoglobin = methaemoglobin (no ability to bind O2)
↑ levels can be fatal = Chocolate Blood Dz nitrite toxicity NOT in seawater, bc salt competes w/ nitrite for uptake, therefore limiting its toxicity in a reef tank for corals/sponges/invertebrates
What should a filtration system remove?Protein w/a protein skimmer
What are most filtration systems designed to do?Nitrification!
*Should you treat a sick fish in your main tank? Why not? Where you should you put it?No!!!!!, should treat in hospital tank bc don’t want to kill your nice little living nitrification guys!
*Should you pick up a fish w/ dry hands, a paper towel, or gloves? Why not?No, destroy mucous layer. Wet hands!
*What do fish RBC’s look like? Are their neutrophils highly phagocytic?RBC’s nucleated, neutrophils not highly phagocytic
What is excreted by the gills? What does it to do the pH? What effect does this have on the ammonia levels?CO2, reduces pH, reduces free/dangerous ammonia (NH3)
What does exposure to CO2 do to respiration? Are fish sensitive to ↑s in CO2?Reduces affinity of hemoglobin to O2 (Bohr effect), therefore fish are very sensitive to even ↓ levels of CO2
What are some negative effects of ↑ levels of CO2 → ↓er water pH that can be inadvertently czd by adding more O2 to the water?Exopthalmos, swim bladder distention, neprhocalcinosis this chemical is often added to human water systems.
What does it react w/ to produce a toxic compound? How do you remove/inactivate it?ClCoften found in human water supply Cl- + N = Chloramine, which acts on hemoglobin inactivate: aeration, zeolites (clays), activated charcoal
What does alkalinity measure? What 2 types of water are well buffered/stable?Alkalinity = measures buffering capacity of water water from limestone areas & seawater are well buffered
What does hardness measure? What is considered soft water? What spp prefer soft water?Hardness = measure Ca2+ & Mg2+ ion
Soft water = <50ppm, preferred by amazonians
What does salinity measure? What spp can adapt to very ↑ salt levels (>37ppt)?Salinity: total dissolved salts. tilapia can adapt well
What 3 divalent cations are dmging?Zinc, Copper, Cadmium
What is 1 reason algae are useful? What are 2 reasons they can be dangerous?Useful: feed rotifers (invertebrates that fish eat)
Dangerous: blooms can ↓er O2 levels, some produce toxins that can effect fish & humans (ex. barracuda/grouper poisoning from ciguatera toxin, paralytic shellfish poisoning)
What is the difference btwn a diatom & a dinoflagellate?Diatoms = don’t swim
Dinoflagellates = swim
*What are the 2 major dangers of jellyfish blooms? What lesions can they cz?(1) Directly dmg gills/skin cz ballooning lesions on gill arch
(2) Lesions can xfer harmful bacteria that cz 2⁰ infxns

Bacterial dzs!

Question Answer
*This gram (-) rod czs hemorrhagic septicemia in freshwater fish. Is it zoonotic? What are predisposing factors?Aeromonas hydrophila (aka A. liquefaciens)
Predisposing factors:
↑ water temps (tropics)
Poor water oxygenation
↑ organic load in water
What are 2 dzs associated w/ Aeromonas hydrophila (aka A. liquefaciens)?(1) Spring viremia (Rhabdovirus carpio) in carp
(2) EUS, Epizootic Ulcerative Syndrome in asia
Where can you isolate Aeromonas hydrophila (aka A. liquefaciens)?Blood
What are 5 common gross lesions of gram(-) bacteremias?(1) Fish are dark (Hyperpigmented)
(2) Hemorrhages at base of fins/vent
(3) Intussusception of intestine
(4) Ascites
(5) Kidneys/spleen swollen & soft
*What is 1 of the most economically important dzs of cultured & wild fish, mostly freshwater, recently in cod. Czs hemorrhagic muscle lesions. Large bacterial colonies in the myocardium = pathognomonicFurunculosis, czd by Aeromonas salmoncida
Where can you isolate Aeromonas salmoncida?Spleen
Which gram(-) rod produces septicemia, hemorrhageic skin lesions/congestion at fin bases in freshwater fish, usually at ↑ temps? Also czs keratitis/ opthalmitisPseudomonas fluorescens
This czs “Red Spot Dz” in japanese/european eels?Pseudomonas anguilliseptica (aka Sekiten-Byo)
Where can Pseudomonas anguilliseptica be found? What are the other lesions?Found in skin, muscle, heart
Hemorrhages & macrophage infiltrates in these tissues as well
This dz of Salmonids at relatively ↓ water temp features stumpy/atrophied lamellae covered in the bacteria. Clinical sign incld lethargy & ↓ fright response?Pseudomonas anguilliseptica
What bacteria is the cz of “Enteric Redmouth Dz” (ERM) of freshwater fish?Yersinia ruckeri
What are the common clinical signs of Yersinia ruckeri infection?Subcutaneous/submucous hemorrhages around mouth, fins & vent. Also show lethargy & anorexia
*What bacteria czs Enteric Septicemia of catfish?Edwardsiella ictaluri
What is the 1⁰ lesion of Edwardsiella ictaluri in catfish?Hole in the head
*What is the dz called in Vietnamese catfish?White Spot Dz
This is also a warm water dz of catfish in the Southern US & eels in Asia. Dermal & muscular lesions are the hallmark, often gas-filled. What is its other, disgusting name?Edwardsiella tarda
Aka “Emphysematous Putrefactive Dz of Catfish”
What is the other name for myxobacterial dzs?Yellow Pigmented Bacterial Dzs (YPD)


Question Answer
*This myxobacterial dz is necrotizing & bacteria form “columns” or “haystacks”. What temperature must the water be above to see dz?Columnaris dz, czd by Flavobacterium columnare
***Water must be 18⁰ C to see dz***
*What is Columnaris dz called if seen in seawater? What type of lesion do you see?Tenacibaculum maritimum, see lesions at the commisure of the mouth
*What type of dz is Columnaris dz & what are the 1⁰ lesions? (3)Type: Necrotizing dz:
(1) Pale “saddlepatch” around the dorsal fin
(2) “Cotton wool mouth”
(3) Necrosis of the gills
What is 1 of the most important dzs of cultured fish on a worldwide basis? The most significant in Canadian hatcheries, often coincides w/ spring thaw?Bacterial Gill Dz (BGD), czd by Flavobacterium branchiophilum
What is the pathogenesis of Bacterial Gill Dz?Bacteria on gill surface → fused lamellae/clubbing → crash in blood O2 levels to 30% of normal in minutes bc of vasoconstriction of branchial vessels
What is an early sign that helps differentiate Bacterial Gill Dz from other gill dzs?↓ appetite
What is the typical appearance of a fish w/ Bacterial Gill Dz?Flared opercula
Eosion of trailing edges
Crowding at inlets
Foaming of water from mucus production
*What dz in North America shows a classic tail rot appearance & general necrotizing myositis?Bacterial Cold Water Dz, aka “Peduncle dz”, czd by Flavobacterium psychophilum
*What are 5 other dzs associated w/ F. psychophilum?(1) Rainbow Trout Fry Syndrome (RTFS)
(2) Dissolving Head Dz
(3) Necrotic Myositis
(4) Strawberry Dz of Rainbow Trout
What kind of tissue does F. psychophilum prefer?Connective tissue (ex. sclera, vertebral column)
*What does Strawberry Dz look like? What czs the spaces seen in the dermis (histologically)?Massive inflammatory response, red lesions, looks like Type IV hypersensitivity. Spaces in dermis czd by osteoclasts resorbing scales
*What gram(+) bacteria is an extremely important dz of Salmonids & czs multifocal pyogranulomas, encephalitis, kidney dz & spawning rash lesions?Bacterial Kidney Dz (aka Dee Dz, Kidney Dz)
Czd by Renibacterium salmoninarum
In Bacterial Kidney Dz, If renal granulomas are severe, what can be the result in terms of the kidney? If they rupture?Compression atrophy of nephrons (wire loop glomerulus, Ag/ Ab complexes on basement membrane). Ruptured granulomas → peritonitis
What are 2 other organs that can be the targets of Bacterial Kidney Dz? What can that lead to?(1) Heart, esp. epicardium → fibrinous epicarditis, myocardium → necrosis of compact layer
(2) Choroid of the eye → exopthalmos
*Why is Fibrinous Epicarditis such a problem for fish?Important bc they rely more on stroke volume!
(CO = SV x HR)


Question Answer
What bacteria czs “Cichlid Bloat”?Clostridium hastiforme
*What zoonotic bacteria czd meningitis & death in 3 people handling tilapia in Toronto?Streptococcus iniae
(ZOONOTIC ..... obviously)
*What was effect of Streptococcus iniae on the Caribbean in 1999?Epizootic, led to death of many/most reef fish, 1 of very few confirmed cases of such severe loss in wild fish populations
What is an important dz of yellowtail in japan, also in North America, czs hemorrhagic septicemia in kidney/spleen or multifocal granulomas?Pasturellosis czd by Photobacterium damselae subsp. piscicida
What organism is Pasturellosis associated w/? What is produced?Closely associated w/ scombroid poisoning, produces histamine
*Which organism czs cholera & gastroenteritis in humans & was also the commonest cz of bacterial dz in the marine environment. It is the marine equivalent of furunculosis, czing large, necrotizing lesions in muscle. What has helped control this dz?“Classical” vibriosis in most marine fish, czd by vibrio (cholera in humans, vibrio anguillarum in eels). Adjuvant vaccines now largely have this dz under control
What does this bacteria cz in eels?“Red Pest”
What are the classical lesions?Petechial hemorrhage on abdomen, hemorrhage/congestion at base of pectoral/pelvic/anal fins, dermal ulceration
*What is a zoonotic bacteria that czs self-limiting infxns of the skin in people & czs dz in fresh/marine/cold/warm water/cultured/wild fish. Esp. effects fish at the bottom of the “pecking order”?Mycobacterium marinum, fortuitum & chelonei
(Mycobacterium tuberculosis is the dangerous 1 in humans)
*What are some pathological lesions associated w/ this Mycobacterium spp?Miliary “Millet seed” lesions in liver, spleen, kidney, tubercules (w/o langhan’s giant cells, carried to melanomacrophage centers
*What organ do you expect to be effected if scales are standing up indicating problems w/ water balance/ regulation?The kidney!
What is the main differential for mycobacteriosis?Nocardia
What is an extremely small intracellular bacterium that czs multi-focal granulomas in many organs. Is this the same czative agent for human dz?Francisella, NOT the same organism that czs Tularemia in humans

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