Aquatic Systems Flashcards
Temperature ranges for cold- vs. cool- vs. warm-water fish
Cold = 32-55ºF
Cool = 50-70ºF
Warm = >70ºF
What are the top 5 parameters of water quality?
- Temperature
- Dissolved Oxygen
- pH
- Ammonia
- Nitrites and Nitrates
How do open and closed water systems differ?
Open (pens, raceways)
- reliable water source
- excellent water quality
- can hold high stocking densities
Closed (ponds, aquariums)
- less total water required
- better control of the system
- can only hold a limited stocking density
What products do fish excrete?
- Ammonia (1º waste product/excreted through their gills)
- CO2
- Solid & liquid waste
Describe the nitrification process
- Fish metabolize protein into ammonia & excrete thru gills. Ammonia = toxic.
- Aerobic bacteria on biofilter consume ammonia and produce nitrite. Nitrite = toxic.
- Aerobic bacteria on biofilter consume nitrite and and produce nitrate. Nitrate ≠ toxic unless in high levels.
Biofilter medium can take 6-8 weeks to accum. adeq. nitrifying bacteria
As a biofilter cycles, ammonia will rise until sufficient nitrifying bacteria are present to consume the ammonia and convert it to nitrite. Ammonia levels will then begin to decrease while nitrite levels increase. Nitrite levels will continue to increase until sufficient bacteria are present to consume the nitrite and convert it to nitrate. Unless many plants are present, nitrate levels will rise slowly until a water change is performed.
Ways to decrease water temperature
provide shade; increase water flow
Your fish are gulping at the surface, appear lethargic, and have increased ventilation efforts. How do you address the problem in an open vs. closed system?
Low dissolved oxygen levels (warm temperatures, animal/plant respiration, organic decomposition)
- Open system: increase water flow, add in a water agitator
- Closed system: air stone
Average DO requirement for fish
Minimum of 5ppm
pH ranges:
1. FW
2. SW
3. Fatal levels
- FW = 6.8-7.8 (7.2)
- SW = 7.8-8.6 (8.2)
- Fatal levels = 4.0 & 11.0
FRESHWATER Water Quality Parameters
The ideal
- ammonia
- nitrite
- nitrate
- salinity levels in aquatic systems
FRESHWATER Water Quality Parameters
- ammonia = < 0.02ppm
- nitrite = < 0.10ppm
- nitrate = < 100ppm
- salinity = 0ppt
MARINE Water Quality Parameters
The ideal
- ammonia
- nitrite
- nitrate
- salinity levels in aquatic systems
MARINE Water Quality Parameters
- ammonia = < 0.02ppm
- nitrite = not applicable
- nitrate = < 100ppm
- salinity = 32ppt
Nitrite ions compete with Cl- ions -> high [NaCl] decr. Nitrite uptake
3 major functions of gills
- Respiration (gas exchange)
- Excretion (ammonia)
- Osmoregulation (ion-mineral balance)
Name of strucure on the gills where respiration (gas exchange) occurs
Lamellae
Difference b/w freshwater and saltwater fish OSMOREGULATION
Osmoregulation = how fish maintains homeostasis of salt ions and water
Freshwater = constant water gain and salt loss
- [salt] in blood is GREATER than [salt] in water -> salt constantly moving OUT
- water is constantly moving IN
- constantly reabsorbing salts from urine and excreting dilute urine in order to preserve salt ions
- never drink water
Saltwater = constant water loss and salt gain
- [salt] in blood is LESS than [salt] in water -> salt constantly diffusing IN
- water constantly moving OUT
- constantly drink water to stay hydrated -> excess uptake of salt ions present in saltwater -> excess actively excreted out thru gills
Ions: high->low, Water: low->high
Pollution and low oxygen are __?__ stressors
Chemical
5 clinical signs of disease in fish
- changes in behavior
- decrease in appetite/ravenously hungry
- changes in coloration
- development of external lesions
- increased morbidity and mortality
