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Fish Health Management Lab 1: Water Quality

Fish Health Management Lab 1: Water Quality. January 25 th , 2010 David Burbank burb2155@vandals.uidaho.edu. Aquatic Environment. Water quality is one of the most important factors to maintain fish health. Poor water quality causes more losses in aquaculture than any other problem.

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Fish Health Management Lab 1: Water Quality

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  1. Fish Health ManagementLab 1: Water Quality January 25th, 2010 David Burbank burb2155@vandals.uidaho.edu

  2. Aquatic Environment • Water quality is one of the most important factors to maintain fish health. • Poor water quality causes more losses in aquaculture than any other problem. • Factors that influence water quality/quantity in aquaculture: • Feed rates • Feed types • Flow rates • Tanks/containers (flow dynamics) • Temperature

  3. Water quality testing • Daily or weekly tests • Basic tests • Relatively quick and inexpensive • i.e. Temp, DO, Cl, ect… • Semi-annual or annual • Extensive & more precise • Expensive and time consuming • i.e. Heavy metals • Are catered to specific concerns for the facility

  4. Dissolved oxygen Temperature Nitrogen compounds Ammonia (NH3) Nitrite (NO2-) Nitrate (NO3-) pH Alkalinity Carbon Dioxide Hardness Hydrogen sulfide Total suspended solids Chlorine Daily or Weekly

  5. Dissolved Oxygen • Inadequate DO can cause mortality and contribute to chronic stress and ill health • Solubility • dependent on: • Temperature • Elevation • Salinity • Safe levels • greater than 5 mg/L for salmonids • greater than 3 mg/L for warm water fish Mg/L

  6. Dissolved Oxygen • Uptake influenced by condition of gills • Partial pressures are important • If lamellae are not healthy, the demand may not be met. • Water DO levels below saturation can adequately provide saturation of hemoglobin, however a safety margin should be maintained.

  7. Oxygen Requirements • Dependent on Temperature • Metabolic increases with temperature • Dependent on demands of organism • Energetic demands: swimming, digestion, etc. • Energetic costs of ventilation • Efficiency of uptake varies in species

  8. Effects metabolic rate doubles for every 8C increase Influences spawning Influences growth Influences pathogens Fish Categories warmwater coolwater coldwater Temperature

  9. Types dissolved gas ammonia ionized (NH4+) un-ionized (NH3) nitrite (NO2-) nitrate (NO3-) Nitrogen Compounds

  10. 1½ O2 1½ O2 NH3 NO2- NO3- nitrosomonas nitrobacter Nitrification • Requires 3 moles oxygen to convert one mole of ammonia to nitrate • Nitrification is an acidifying reaction

  11. Ammonia (NH3) results from the breakdown of fish feed, and waste Two forms: ionized (NH4+) un­ionized (NH3) Un­ionized ammonia concentration is a function of pH and temperature Chronic exposure (un­ionized form) 0.06 mg/L is toxic to warm water fish 0.03 mg/L is toxic to salmonids Ammonia

  12. Nitrite (NO2-) is the intermediate product in the breakdown of ammonia to nitrate (nitrification) Nitrite levels greater than 0.5 to 0.6 mg/L or 10 times higher than the toxic threshold for un­ionized ammonia are toxic to fish Catfish will tolerate 13 mg/L Salmonids will tolerate <0.3 mg/L Decreasing pH increases toxicity Nitrite

  13. Brown blood disease (Methemoglobinemia) Iron in the heme molecule is reduced and cannot transport oxygen Blood appears dark in color and fish cannot meet oxygen demands Treatment Salt Chloride ions out-compete nitrite Recommend 10:1 ratio Hypertrophy and hyperplasia in the gill lamellae Lesions/hemorrhaging in thymus Nitrite

  14. Nitrate (NO3-) is the final breakdown product in the oxidation of ammonia Nitrate is relatively non­toxic to fish at concentrations up to 3.0 mg/L May be problem in embryo development Nitrate

  15. Nitrogen thresholds for salmonids

  16. Measure of the hydrogen ion concentration 1-14 scale less than 7 acidic greater than 7 basic Safe range generally 6.5-9.0 (species variable) pH

  17. Sources bi-product of respiration of fish and phytoplankton wells carboniferous rock (i.e. black shale, coal) Removal intense aeration buffers calcium carbonate sodium bicarbonate Carbon Dioxide CH2O (food) + O2CO2 + H2O

  18. Alkalinity is the capacity of water to buffer against wide pH swings Acceptable range 20-300 mg/L Alkalinity Bicarbonate: CO2 + H2O  H+ + HCO3- Carbonate: HCO3- H+ + CO3- Effects of calcite lime: CaCO3 + CO2 + H2O  Ca+2 + 2HCO3- *Dolomite CaMg(CO3)2 yields 4HCO3-

  19. Hardness is the measure of divalent cations Calcium Magnesium Suggest > 50 ppm Hardness is used as an indicator of alkalinity but hardness is not a measure of alkalinity Magnesium or calcium sulfate increases hardness but has no affect on alkalinity If hardness is deficient then fish grow poorly Hardness

  20. Source Well water Ponds shift from aerobic to anaerobic breakdown of wastes Can develop under net pens Extremely toxic to fish Removal Intense aeration Draining and drying of pond Hydrogen Sulfide

  21. Types suspended settleable Sources runoff uneaten food feces Safe levels less than 1,000 mg/L Removal filtration settling chambers Total Solids

  22. Suspended Solids • Potential problems • Source of irritation/nutrients on gills • Inflammation and damage to gills • Bacterial or fungal colonization on gill surface • Reduce oxygen transport • 80 - 100 ppm TSS reasonable for salmonids

  23. Chlorine • Chlorine, (sodium hypochlorite or calcium hypochlorite) reacts with water to form strong acid • Cl2 + H20 H0Cl H+ + Cl -

  24. Disinfectant municipal water cleaning tanks and equipment Safe levels less than 0.03 mg/L Removal intense aeration sodium thiosulfate 1 mg/L for every mg/L chlorine Sunlight Filtration (carbon filters) Chlorine

  25. Chlorine toxicity • Acid is more toxic than hypochlorite ion • Destroys epidermal surfaces (especially gills) • Toxicity depends on temp, DO, free chlorine present, presence other pollutants • Residual chlorine (free plus chloramine)0.2 - 0.3 ppm kills fish rapidly • Chlorine and nitrogenous organics = chloramines that are very toxic

  26. Heavy Metal Contaminants • Heavy metals - Cd, Cu, Zn, Hg, must be all < .1 mg/L. • In aquaculture watch out for plumbing systems (copper, zinc alloys) PVC is preferred choice. • Soft water makes a difference in toxicity of metals

  27. Problem gasses nitrogen maintain less than 110% Problem sources wells and springs leaky pipes Dams dorsal view Popeye/exophthalmia leaky pipe Dissolved Gasses

  28. Characteristics of gas bubble disease • Bubbles under skin • fins • tail • mouth • gas emboli in vascular system = death • similar to bends or decompression sickness

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