Exotics Top Topics - Environmental Aquatic Disorders Flashcards
key health issues related to environmental factors in fish are related to what?
ammonia, nitrite, pH, temperature, bicarbonate, heavy metals, & dissolved gases
T/F: most health problems in fish are made worse by poor water quality or inappropriate water temperatures
true
what is critical in preventing environmental aquatic diseases in fish?
regular tank maintenance & quality water monitoring are critical
what is the classic case presentation of acute new tank syndrome?
convulsive swimming/spinning
what is the classic case presentation of sub-acute to chronic new tank syndrome?
lethargy, anorexia, increased respiration, & death
damaged gills
what is the pathophysiology of new tank syndrome?
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
how is new tank syndrome diagnosed?
measure ammonia & nitrate levels
how is new tank syndrome treated?
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
how is new tank syndrome prevented?
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)
how long can it take for a tank to develop its own healthy biofilter to process nitrogenous waste?
up to 6 weeks or more
what is the classic case presentation of of old tank syndrome in a marine system?
may see algal growth, recession of corals
what is the classic case presentation of of old tank syndrome in a freshwater system?
may be no obvious tank problems or disease fish prior to a system crash
what is mortality like in old tank syndrome?
high mortality rates in a previously thriving, long-established tank - possible changes in appetite, attitude, or activity
what is the etiology of old tank syndrome?
primarily a problem of very low to non-existent alkalinity
what is the pathophysiology of old tank syndrome?
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
how is old tank syndrome diagnosed? how is it prevented?
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
how is old tank syndrome treated?
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
how is old tank syndrome prevented?
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
T/F: old tank syndrome is less common than new tank syndrome
true
why does old tank syndrome usually occur?
usually due to tank mismanagement or benign neglect but strongly driven by alkalinity & pH