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By: Michael Kaufman Fisheries Technician Water Quality Unit University of Pittsburgh at Johnstown ◦ B.S. Biology PFBC ◦ Fisheries Technician, Water Quality Lab Collect & receive water samples from 14 PFBC fish hatcheries as defined by PA DEP National Pollutant Discharge Elimination System (NPDES) permits Perform analyses on hatchery samples for Carbonaceous Biochemical Oxygen Demand (CBOD), Total & Dissolved Phosphorous (PO4), Total Suspended Solids, pH, Temperature, and Dissolved Oxygen Trout in the Classroom & Water Quality Fish live in water Fish receive life support from water Fish breathe in water (obtain oxygen from) Fish excrete in water Must maintain water quality at a level that provides an environment conducive to fish health and growth Most disease problems can be avoided with proper management of water quality ◦ Poor water quality can act as a stressor weakening the immune system of the fish making them more prone to infectious disease ◦ Poor water quality can cause massive mortality The success or failure of fish culture is primarily determined by water quality Dissolved Oxygen Temperature pH Nitrites/Nitrates Ammonia Chlorine DO is a relative measure of the amount of oxygen that is dissolved or carried in a given medium such as water Standard Units = milligrams per liter (mg/L), parts per million (ppm), or Percent saturation (%) Abundant in the atmosphere, comprises 21% of atmosphere Generally measured with a dissolved oxygen probe Very soluble in water Second most abundant gas in water (nitrogen is first) ↑water temperature, ↓DO concentrations ↑ barometric pressure, ↑ DO concentrations Primary limiting factor for growth and fish health In general, minimum dissolved oxygen should be ≥ 100% of saturation or ≥ 5ppm (mg/L) As DO increases, metabolism increases ◦ A trout uses five times more oxygen while resting at 80° F (26.7° C) than at 40° F(4.4° C). As temperature increases, the dissolved oxygen saturation level in the water decreases, while the dissolved oxygen requirement for the fish increases DO < 5.0, slows fish growth and increases stress DO < 1.0, can be lethal to fish As temp. increases, the equilibrium amount of DO in water decreases Atmosphere Oxygen diffuses out of water column Oxygen diffuses into the water column Oxygen > 100% Saturation Oxygen < 100% Saturation Water Column DO should not exceed 100% saturation for fry and small fingerlings D.O. supersaturation can cause mortality in fry and small fingerlings Supersaturation - refers to a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances Influent DO – in our case the DO in the water introduced to the tank Fish density – more fish use more O2 & food and create more waste Temperature – water holds less O2 at higher temps Atmospheric pressure – water holds less O2 at lower pressure Excess organic matter that leads to decomposition Water velocity Water clarity Normoxic - Having a normal oxygen concentration; typically 20-21% in the atmosphere Hypoxic - reduced oxygen content in air or a body of water detrimental to aerobic organisms Anoxic - a total depletion in the level of oxygen or an extreme form of hypoxia Environmental Hypoxia leads to severe mortality Low O2 levels can act as a stressor and cause chronic mortality and affect growth Lethargy Congregation of fish near air-water interface or near water inflows Mouth open, gills flared High mortality after feeding Morts will have curved back and flared gills Little or no growth Low or no reproduction Ulcers/Tumors Susceptible to other diseases Decomposer organisms (mainly bacteria) also consume oxygen in the system Sometimes they consume oxygen faster than it can be produced or replenished within the system A sudden increase in organic matter can create a spike in decomposition activity which can cause fish kills Brook trout require relatively high concentrations of dissolved oxygen in water compared to other fish and even other trout species Dissolved O2: Ideal dissolved oxygen levels should be10-12 ppm, 8ppm is the absolute minimum for developing eggs and alevins, and 5ppm is the absolute minimum for fry Optimal dissolved oxygen levels for trout are not well documented, but appear as the following: ◦ Rainbow trout: ≥ 7 mg/L at temperatures ≤ 15.0°C and ≥ 9 mg/L at temperatures > 15.0°C. ◦ Brown trout: ≥ 9 mg/L at temperatures ≤ 10°C and ≥ 12 mg/L at temperatures > 10°C. ◦ Brook trout: ≥ 7 mg/l at temperatures < 15°C and ≥ 9 mg/l at temperatures ≥ 15° C. Add aeration (additional airstones) Lower water level so that your filter outflow creates a mini waterfall Check your water temperature: decrease slowly if needed Stop feeding for a day or two Decrease fish density if low dissolved oxygen levels persist How warm or cold the water is Degrees Fahrenheit (°F) or degrees Celsius (°C) Fish have specific temperature ranges Pathogens have specific temperature ranges Temperature can directly influence DO Temperature: Range for brook trout is 3372°F (0.6 -22.2°C), but Optimal is 48-52°F (8.9-11.1°C) Studies have determined that brook trout cannot tolerate sustained water temperatures exceeding 77°F (25°C) and prefer water temperatures less than 68°F (22°C). Brook trout are less tolerant of warmer water temperatures than brown or rainbow trout. When temperature is too high or too low, fish can become stressed Avoid sudden changes in temperature ◦ Slight temperature changes can act as a stressor (>1-2°F) As temperature increases, metabolism increases Prolonged exposure to extreme temperatures can be fatal Symptoms ◦ Below 38°F (3.3°C) - Will suppress fish appetites and slows digestion processes. ◦ Above 68°F (20°C) - Partial digestion of food. Water holds less dissolved oxygen. Trout will gasp for oxygen at water surface and crowd near the filter outflow and/or chiller coil. Fixes ◦ Adjust temperatures accordingly using the chiller unit and thermometer. At any given temperature the intensity of the acidic or basic characteristic of the solution is indicated by pH or hydrogen ion activity. pH is the negative logarithm of the hydrogen ion concentration Expressed as Standard Units (S.U.) pH scale is 0 to 14 pH of 7 is neutral, below 7 is acidic, above 7 is basic Generally measured using: ◦ a pH meter and indicators (buffers @ 4.01 SU and 7.00 SU) ◦ Color wheel (universal indicator paper) Color charts needed to determine pH range ◦ Litmus paper Blue indicates basic (7-14 SU) Red indicates acidic (0-7 SU) Brook trout have evolved to be the most tolerant of the trout species to acidic conditions. Adult brook trout can tolerate pH levels as low as 5.0 pH: Ideal pH range for trout is 6.0 – 8.2 ◦ pH outside this range negatively effects fish growth and reproduction Extreme pH levels can be lethal to fish ◦ Levels of 4.0 and lower or 9.5 and higher are typically lethal pH range of most of hatcheries is 7.2-8.0 Lower pH increases toxicity of many metals. Water with a pH lower than 6.0 can cause metals found in soil and rocks to dissolve and suffocate and/or poison aquatic organisms. Higher pH increases toxicity of ammonia pH of common liquids: bleach=12.7, blood=7.3, milk=6.8, orange juice=4.2 Fish can handle small changes in pH. They are able to buffer by exchanging ions between their internal (blood) and external (water) environments. The most important site of ion transfer are the gills This ion exchange requires external Cl- for internal HCO3-, and external Na+ for internal H+. Blood acidosis (low pH) is corrected by reducing the uptake Cl- by the gills and to some extent increasing uptake of Na+. The reduction in Cl- uptake thus reduces HCO3excretion, and the increase in Na+ uptake increases the excretion of H+. Then net effect is a compensatory increase and return to normal blood pH. Mild cases - fish may become sluggish and stay near the surface of the water. Severe cases - trout will become excited, jumping out of water, racing back and forth. Acute ◦ Tremors and hyperactivity Chronic ◦ ◦ ◦ ◦ ◦ ◦ Increased mucus production Poor growth Reproductive failure Increased accumulation of heavy metals Respiratory stress Increased susceptibility to disease Gill, mucus cells and epithelial cells are hypertrophic Corneal damage Conduct partial water change. Know the source water pH and aquarium pH. They should be within +0.5 standard pH units to safely exchange the water. Temper pH slowly, using a commercial pH Up or pH Down product sparingly and only after trying other alternatives pH Up – increases pH of system using Sodium Carbonate 10-19% pH Down – decreases pH of system using Sulfuric acid <10% Ammonia is a compound of nitrogen and hydrogen that can be found in the atmosphere. Produced from the putrefaction (decay process) of nitrogenous animal and vegetable matter. Ammonia ions are also found in the metabolic byproduct (animal waste) of animals. In fish it is excreted directly into the water. Reported in mg/L or ppm Usually the second biggest contributor to poor fish health and growth Causes gill tissue hyperplasia Decreases the ability of hemoglobin to carry oxygen Gill Hyperplasia Normal Gill Tissue Maximum recommended levels for chronic exposure: ◦ Salmonids - 0.0125 ppm un-ionized ammonia per liter Ionized Ammonia (NH4 +) ◦ Upper limit for trout is 0.5 ppm ◦ Fish can be stressed at levels of 0.3 ppm Exceeding the upper limit can result in reduced growth and damage to gills, liver and kidneys As pH increases, the toxicity of NH3 increases ◦ For example, a pH increase from 8.0 to 9.0, increases the amount of NH3 by 10 times The interaction between WQ parameters is critical Excess food will increase ammonia levels in your aquarium. Do not overfeed your trout. Immediate ◦ Conduct small (5-10 gallon) water changes. When doing this use your siphon clean and take water from the bottom of your aquarium. That is where ammonia will settle most. ◦ Turn off filter and add a biological enhancement agent or biological filter additive containing live bacteria that improves the development of the biological filter and helps clean a dirty aquarium. Leave filter off for at least 2 hours before turning it back on allowing biological agent time to work. ◦ Do not feed your trout for a day or two. Daily ◦ Feed smaller amounts of food ◦ Use a turkey baster to take out excess food 15-20 minutes after trout feed. This will prevent excess water changes and targets areas where food tends to accumulate. Long term ◦ Do NOT conduct too many water changes. Too many water changes = aquarium not cycling ◦ Ensure that your good bacteria populations are healthy. The biological process that converts ammonia and nitrite (both toxic to fish) into relatively harmless nitrogen compounds (nitrates). Stage One – Ammonia Spike ◦ Ammonia is formed from all uneaten, decayed food, and waste generated by metabolism in the fish, where it is excreted directly into the water. It breaks down to form ionized or unionized ammonia. ◦ The ionized form, Ammonium (NH4+), is present if the pH is below 7, and is not toxic to fish. The unionized form, Ammonia (NH3), is present if the pH is 7 or above, and is highly toxic to fish. Stage Two – Decrease in Ammonia & Increase in Nitrites ◦ Nitrosomonas bacteria colonize the filter and derive all the energy they need for growth and reproduction from converting ammonium (NH4+) into nitrites. Nitrites (NO2) are highly toxic to fish. Nitrites (NO2) destroy the hemoglobin in the fish's blood and eventually prevents the blood from carrying oxygen. Stage Three – Decrease in Nitrites & Increase in Nitrates ◦ Nitrobacter bacteria begin to colonize the filter and feed on the nitrites (NO2) produced by the Nitrosomonas bacteria. They convert the nitrites (NO2) to nitrates (NO3), which are far less harmful to fish. In doing this, they too begin to multiply their numbers until most of the nitrites (NO2) being produced are converted to nitrates (NO3). The byproducts, then, of the nitrogen cycle is the carbon dioxide exhaled by the fish and the nitrates produced by the bacteria. Both of these are used up by some degree by any aquatic plants present. The carbon dioxide is used up by plants in the action of photosynthesis, which produces oxygen back into the water and the nitrates are consumed by the plants as fertilizer to aid their growth. Ammonia 2NH4+ + 3O2 2NO2- + O2 Nitrites Nitrites 2NO2- + 2H2O + 4H+ + energy 2NO3Nitrates Nitrites ◦ If nitrates present in aquarium (10ppm-40ppm): 0–2 ppm ◦ If nitrates NOT present in your aquarium: 0-0.25 ppm; any higher will stress trout ◦ A cycled aquarium should have little to no nitrite readings (0-0.5) Nitrates ◦ 5 – 40 ppm Ammonia ◦ If nitrates present in aquarium (10ppm-40ppm): 0-1 ppm ◦ If nitrates NOT present in your aquarium: 0-0.25 ppm; any higher will stress trout ◦ A cycled aquarium should have little to no ammonia readings Do not change aquarium water too often. Changing will delay the growth of bacteria needed to drive the nitrogen cycle and will stress the fish. ◦ Only change when levels are extremely high. High levels are needed in order for complete the nitrogen cycle completely. Do not change filter media as that is where the needed bacteria is located. Do not overfeed. Acute: ◦ Hyperexcitability Chronic ◦ Enlargement of gill tissue in both cell size and number ◦ Elevated blood pH ◦ Osmoregulatory disturbance ◦ Increased tissue oxygen consumption ◦ Reduced growth ◦ Increased susceptibility to disease Nitrite (NO2-) – high concentrations occur after ammonia has peaked because nitrate oxidizing bacteria (nitrate nitrifiers) require time to become active Trout will become stressed at levels above 0.15 ppm Levels above 0.55 ppm are lethal to trout Most levels in PFBC hatcheries are < 0.1 ppm High ammonium concentrations in alkaline water inhibit nitrate nitrifiers Brown or tan gills due to nitrite converting hemoglobin to methemoglobin ◦ Methemoglobin cannot transport oxygen as well as hemoglobin Lethargy Congregation near water surface and water inflow Should not be disturbed, any stress will cause mortality Small water change, only about 5-10 gallons A biological enhancement agent or biological filter additive Do not feed your trout for about a day or two Slowly decrease water temperature(48-50°F) Conduct a static salt bath. This will reduce stress on your trout and help fight off infections Nitrate (NO3-) is the end product of nitrite oxidation and nitrogen cycle Must be removed through water changes or denitrification Aka “Old Tank” phenomenon Typically not toxic to fish Problem gasses ◦ Nitrogen (primarily) ◦ Causes popeye/ exophthalmia Chlorine is typically what most water authorities treat their water with to rid public water sources of harmful bacteria and micro-organisms Chlorine is lethal to fish at any concentration and therefore cannot be present in the tank water How to remove chlorine from your water: 1. Fill up two 5 gallon buckets. 2. Allow the buckets to sit for at least 48 hours before placing them into your aquarium 3. While your buckets are sitting, you should also occasionally stir the water to help dissipate the chlorine more rapidly Other options: You can also use commercial dechlorinators such as: Prime, AmQuel, AP Tap water conditioner, and Aquasafe Plus Chlorine (Total) Test Kit, Model CN-21P, Hach Total Chlorine Test Kit, Model CN-70T, Hach VWR: $40.25 VWR: $79.93 Pocket Colorimeter™ II, Chlorine (Total), Kit includes SwifTest™ DPD Reagent Dispenser, Hach VWR: $411.78 Chloramines are another type of disinfectant used by water authorities to kill harmful bacteria in water. Ammonia is also added to municipal water supplies to eliminate trihalomethanes (carcinogen). Formation of chloramine occurs through the reaction of chlorine and ammonia. Chloramines are highly toxic to fish. Fish, unlike humans and other animals, do not just swallow water, they breathe it; therefore, the chloramines enter directly into their blood stream, making it difficult for their blood to carry oxygen. Chloramines, unlike chlorine, cannot be removed by allowing your water to sit out for 48 hours. Before using public water for your aquarium, contact your local water authority to see what they treat their water with. Depending on what they treat the water with will determine what you need to do. To remove chloramines, use a commercial dechlorinator that specifically states that it also removes ammonia. If the label doesn't specifically mention that it neutralizes ammonia, then don't depend on it to safely treat water containing chloramines. Acute ◦ ◦ ◦ ◦ ◦ Difficulty breathing Acute necrosis and asphyxiation Extensive mucous secretion Hypertrophy of gill epithelium Mortality Chronic ◦ Hemolytic anemia (abnormal breakdown of red blood cells) ◦ Red blood cells composed of denatured hemoglobin An aquarium is a closed system, with no natural water exchanges and limited space for your trout population; as a result, ammonia, pH, nitrite/nitrate levels and carrying capacity can impact the health of your trout. You need to make sure your aquarium cycles and conduct water changes only when your parameters indicate that you need one. Any Questions?