Exotics Top Topics - Environmental Aquatic Disorders Flashcards

1
Q

key health issues related to environmental factors in fish are related to what?

A

ammonia, nitrite, pH, temperature, bicarbonate, heavy metals, & dissolved gases

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2
Q

T/F: most health problems in fish are made worse by poor water quality or inappropriate water temperatures

A

true

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3
Q

what is critical in preventing environmental aquatic diseases in fish?

A

regular tank maintenance & quality water monitoring are critical

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4
Q

what is the classic case presentation of acute new tank syndrome?

A

convulsive swimming/spinning

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5
Q

what is the classic case presentation of sub-acute to chronic new tank syndrome?

A

lethargy, anorexia, increased respiration, & death

damaged gills

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6
Q

what is the pathophysiology of new tank syndrome?

A

ammonia toxicity or nitrite toxicity - high levels of toxic/un-ionized ammonia or nitrite caused by an underdeveloped biofilter

biofilter contains bacteria needed to emtabolize toxic ammonia waste from fish/uneaten food

nitrite is an intermediate metabolite in the multi-step nitrification of NH3 to nitrate

nitrite can cause brown blood disease at elevated concentration (methemoglobinemia) because methemoglobin forms as a result of nitrite binding to hemoglobin & disrupting the ability for RBC to bind oxygen - RBC with methemoglobin can make blood look brown instead of red, but normal appearing blood may still have significant amounts of non-functional RBC

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7
Q

how is new tank syndrome diagnosed?

A

measure ammonia & nitrate levels

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8
Q

how is new tank syndrome treated?

A

assuming pH of water source & system water are similar, consider a water change to drop un-ionized ammonia levels (to < 0.05mg/L) and to reduce nitrite levels

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9
Q

how is new tank syndrome prevented?

A

add commercially available nitrifying bacteria to a tank with no fish & feeding the bacteria with fish food or ammonium chloride

bacteria can also be added using water, filter media, or substrate from an established healthy tank with no major history of disease (still biosecurity risk)

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10
Q

how long can it take for a tank to develop its own healthy biofilter to process nitrogenous waste?

A

up to 6 weeks or more

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11
Q

what is the classic case presentation of of old tank syndrome in a marine system?

A

may see algal growth, recession of corals

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12
Q

what is the classic case presentation of of old tank syndrome in a freshwater system?

A

may be no obvious tank problems or disease fish prior to a system crash

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13
Q

what is mortality like in old tank syndrome?

A

high mortality rates in a previously thriving, long-established tank - possible changes in appetite, attitude, or activity

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14
Q

what is the etiology of old tank syndrome?

A

primarily a problem of very low to non-existent alkalinity

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15
Q

what is the pathophysiology of old tank syndrome?

A

alkalinity includes several different buffer compounds (especially bicarbonate) that not only buffers but acts as a carbon source for the nitrifying bacteria in the biofilter which further acidify the water as they use up the bicarb

biofilter is less efficient as the pH drops and when alkalinity is completely consumed pH can go below 4 & cause a system crash - happens readily if source of water has low alkalinity or may take months to years after the biofilter has been cycled if water quality is not tested regularly

in addition, high organic loads (unsiphoned debris) will acidify the water as it breaks down

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16
Q

how is old tank syndrome diagnosed? how is it prevented?

A

use a water test kit to monitor nitrogen metabolite levels, pH, & alkalinity - may see total ammonia nitrogen 3mg/L->20mg/L, extremely low pH of < 5-6, & low to zero alkalinity

do water tests weekly/monthly depending on starting parameters, fish load, feeding, & managing

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17
Q

how is old tank syndrome treated?

A

change the water & add products to bind NH3 to prevent ammonia toxicity as the pH increases (takes weeks) using binding products with caution

stepped approach - changing out water over a week, using a clean source with a pH that is 7 or lower until most of the total ammonia nitrogen has been replaced & then increase pH using source water

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18
Q

how is old tank syndrome prevented?

A

good tank maintenance including siphoning of debris/cleaning & regular water testing - add new fish/coral slowly & incrementally, large frequent water changes, & iron-based phosphate removing resins

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19
Q

T/F: old tank syndrome is less common than new tank syndrome

A

true

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20
Q

why does old tank syndrome usually occur?

A

usually due to tank mismanagement or benign neglect but strongly driven by alkalinity & pH

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21
Q

what is the classic case presentation of subacute chlorine toxicosis?

A

cloudy eyes, gill inflammation/necrosis, increased respiration/piping at the surface, excess mucus covering gills, & lethargy

22
Q

what is the classic acute case presentation of chlorine toxicosis?

A

sudden death

23
Q

what is the etiology of chlorine toxicosis?

A

chlorine is commonly used to disinfect tanks but it is toxic

24
Q

how is chlorine toxicosis diagnosed?

A

measure free & total chlorine using colorimetric test - should be zero, but can get false negatives if the sample is transported for testing (test on site)

25
Q

how is chlorine toxicosis treated?

A

dechlorination/chlorine binding products

affected fish may benefit from addition of salt (3-5 g/L for freshwater) or reduction of salinity (25g/L for marine systems) to help relieve osmoregulatory burden resulting from damage to gills/skin

26
Q

what puts fish at an increased risk of getting chlorine toxicosis?

A

increased risk if the water source contains chlorine/chloramine & dechlorinating products aren’t used during a routine water change

27
Q

T/F: chlorine toxicosis is not an uncommon cause of acute mortalities in tanks or ponds

A

true

28
Q

what is the classic case presentation of acute on chronic heavy metal toxicity in fish caused by heavy metals/zinc/copper toxicosis?

A

mortality

29
Q

what is the classic case presentation of acute copper toxicosis in fish?

A

blunted gills, abnormal lateral line, distress, darkening, lethargy, & incoordination

30
Q

what is the etiology of heavy metal toxicity in fish?

A

causes derangement of osmoregulatory capacity & electrolyte balance (calcium & sodium levels) & zinc toxicosis can fatally inhibit calcium uptake

copper may also alter sodium/calcium uptake causing damage to gill tissue & causing immunosuppression

31
Q

how is heavy metal toxicity diagnosed in fish?

A

measure heavy metal concentrations & compare to source water & published fish toxicity information

32
Q

how is zinc toxicosis in fish treated? how is it prevented?

A

no known treatment

do not use zinc in tanks or allow coins in tanks/ponds

33
Q

how is copper toxicosis in fish treated? how is it prevented?

A

use chelating compounds & activated carbon filters - if source is known to have copper piping, prevent by running the water before filling the aquarium/tank & checking copper levels

34
Q

what is a common scenario for copper toxicosis in fish?

A

improper use of copper for parasite treatments in fresh or salt water systems or less commonly, due to the addition of water that has been standing on copper pipes

35
Q

what is a commonly seen scenario for zinc toxicosis in fish?

A

using stainless steel or zinc-galvanized tanks (aquaculture) or throwing pennies into an exhibit pond

36
Q

what is the risk for heavy metal toxicity from copper if the pH of water in a system decreases?

A

copper bound to substrate in a system may be released if pH decreases

37
Q

what gases cause gas bubble disease of fish?

A

N2 or less commonly O2

38
Q

what is the the classic case presentation of gas bubble disease in fish?

A

exophthalmos, gas bubbles in the eyes, skin, gill capillaries, & fins, lethargy, buoyancy issues, & sudden mortality

39
Q

what is the etiology of gas bubble disease? what is the pathophysiology of the disease?

A

supersaturation of water with dissolved nitrogen gas or O2

similar pathology to the bends - gas under pressure is taken up by the fish’s body but then bubbles escape the blood/fluids & form air emboli that block blood vessels & damage tissues

40
Q

how is gas bubble disease diagnosed in fish?

A

use a saturometer/total gas pressure meter to measure dissolved gases in water & calculate N2 gas saturation

41
Q

how is gas bubble disease treated?

A

identify & correct the source of supersaturated water if occurring in a system - use degasification units to treat flow through systems in which source water is supersaturated

correct underlying cause (water source or leaking pumps)

degasification in larger recirculating aquaculture systems is also recommended to remove CO2 as well as low levels of N2

42
Q

when does gas bubble disease most commonly occur?

A

when well water is high in N2 gas is used to fill the tank or if the system’s water pump has a leak & is sucking in air & pressurizing it into the water

43
Q

what are the 3 main categories of pH issues causing disease in fish?

A

accidental application of hydrated lime to a pond causing a rapid increase in pH to > 10

old tank syndrome

high CO2 levels decreasing pH

44
Q

how are pH issues causing disease in fish diagnosed?

A

TA <50 = low, inadequate to buffer pH changes

ideal is 100 for freshwater & 150-200 mg/L for saltwater

measure total alkalinity (amount of bicarb in the system vs total water hardness measures calcium & other divalent cations)

45
Q

how is high water CO2 (> 12mg/L) treated for fish?

A

degasification - increased aeration or a separate unit that allows for increased gas exchange) to help remove CO2 gas & increase pH

46
Q

how is low total alkalinity treated for fish?

A

add limestone or dolomite to ponds to increase the alkalinity & hardness - small amount can be added to the substrate or sump of an aquarium

or add baking soda

47
Q

what are 2 very important drivers of water pH for fish environmental diseases?

A

alkalinity & CO2

48
Q

when is CO2 concentration usually lowest in a pond with plants/algae?

A

lowest in late afternoon because all algae use up CO2 through photosynthesis & highest first thing in the morning

CO2 levels are inversely related to dissolved oxygen content & pH

49
Q

T/F: most freshwater fish have an acceptable range of pH but even within range, large fluctuations can be disturbing

A

true

50
Q

what is alkalinity?

A

a measure of buffering capacity of water against acid - measures among other buffer compounds, bicarbonate which is the key buffer