WATER QUALITY What You Need To Know To Keep Your Fish Alive

1. WATER QUALITY What You Need To Know To Keep Your Fish Alive Gary Fornshell, University of Idaho Terry Patterson, College of Southern Idaho

2. To a great extent, the success or failure of fish culture is determined by water quality

3. Water Quality – Why Is It Important? • Your fish live in it • Are supported by it • Receive their oxygen from it • And excrete in it

4. Water Quality – Why Is It Important? • Water quality factors influence and interact with each other • What may cause problems in one situation may be harmless in another • Influences effectiveness/toxicity of treatments

5. Water Quality – Why Is It Important? • Most disease problems can be avoided with proper management of water quality • This includes maintaining water quality at a level that provides an environment conducive to fish health and growth

6. Water Quality Variables • Temperature • Dissolved oxygen • Total ammonia-nitrogen, NH3, NO-2 • Alkalinity • Hardness • pH • Carbon dioxide

7. Water Quality Variables Temperature • For each 10°C (18°F) rise in • temperature the metabolic rate doubles • Controls the reaction rate of chemicals • Influences solubility of gases in water • Influences toxicity of ammonia and therapeutants • Optimum temperature for tilapia growth is 85-88 °F

8. Water Quality Variables Dissolved Oxygen • First limiting factor for growth and fish health • Solubility decreases with increasing temperature and elevation • Respiratory rate increases with increasing temperature, activity and feeding • In general the minimum DO should be ≥ 60% of saturation or ≥ 5 ppm (mg/L) • > 2 ppm in biofilter effluent

9. Water Quality Variables Total Ammonia-Nitrogen • Usually the second limiting factor – nitrogenous waste: feces & feed • TAN includes ammonium ion (NH4+) • and ammonia (NH3) • The proportion of NH3 increases with increasing temperature and pH • < 0.05 mg/L NH3 • < 0.5 mg/L nitrite-N (NO-2) ,

10. Percent of Total Ammoniain the Un-Ionized Form atVarious Temperatures and pH percent Ammonia Temperature (ºF) (pH) 7.0 8.0 9.0 ___________________________________________ 50º 0.19 1.83 15.7 68º 0.40 3.82 28.4 86º 0.80 7.46 44.6

11. Food Water plants Excess food Fishes Algae Feces Nitrate (NO ) Urine 3 Peptides Amino acids Urea Nitrite (NO ) Ammonia (NH ) 2 3 The Nitrogen Cycle

12. Time Required for Bio-Filter to Mature 0.8 8 NO 3 NO 0.6 6 2 NH 3 Nitrites & Nitrates (mg/l) Ammonia (mg/l) 0.4 4 0.2 2 0.0 0 2 6 10 14 18 22 Time in Days

13. Water Quality Variables - Alkalinity • Is the buffering capacity of water – • absorbs acids and/or bases • High alkalinity prevents wide pH fluctuations • Maintain levels between 75-120 mg/L as CaCO3 • 7 grams of alkalinity consumed by 1 gram of NH3

14. Effects of pH on Various Buffers Percent of Total CO 2 100 - = Free CO HCO CO 2 3 3 50 0 5 4 6 7 8 9 10 11 12 pH

15. Water Quality Variables • Hardness 50 – 100 mg/L as CaCO3 • pH 7 – 8 • Carbon dioxide < 20 mg/L

16. Water Quality Variables Total Dissolved Gases • Supersaturation caused by: • leaking water lines • air leak on low pressure side of pump • source of water • mixing cold and hot water • Recommended total dissolved gas pressure <104%

17. Water Balance in Freshwater Fish Water Salts Large quantities of dilute urine Ammonia

18. Stressors • Poor water quality • Environmental conditions • Improper handling

19. Most Fish Diseases Are Stressed Mediated Stress is a physiologic state caused by a procedure, environmental condition or other factor which interferes with the fish’s ability to maintain a “normal” state. It extends the adaptive responses of an animal beyond the normal range or which disturbs the normal functioning.

20. Low Level Mortality 100% Peracute M O R T A L I T Y Acute Usually the first sign of water quality/environmental problems Chronic Time 0%

21. Loading Effects • Number of fish which can successfully live and grow in a given amount of water depends on: • DO level • Metabolic rate of the fish • Amount being fed • Pathogen load • Water exchange rate

22. Management Recommendations • Maintain water quality within suggested guidelines • Maintain fish loadings at optimum levels of 1/4 to 1/3 lb./gallon (1/2 lb./gallon maximum) • Monitor water quality on a regular basis/keep good records

23. Management Recommendations • Low DO: increase aeration; stop feeding • High CO2: increase aeration; add air stripping column • Low pH: add sodium bicarbonate; reduce feeding rate; check ammonia & nitrite • High NH3: exchange system water; reduce feeding rate; check biofilter, pH, alkalinity & DO in biofilter • High nitrite: exchange water; reduce feed; add 6 ppm chloride per 1 ppm nitrite; check biofilter, pH, alkalinity & DO in biofilter

24. Good Stuff To Know • ~ 300 square feet biofilter material per 100 lbs. fish • Add 0.125 to 0.167 lbs. baking soda/ 100 gallons to maintain alkalinity • Add 0.275 to 0.413 lbs salt/100 gallons to maintain chloride levels of 200 – 300 ppm • Do not make any rapid changes to any WQ parameter, except to increase DO

25. Resources • SRAC Publications: http://www.msstate.edu/dept/srac/publicat.htm • Hach WQ test kits: http://www.hach.com/ • LaMotte WQ test kits: http://www.lamotte.com/ • Equipment Suppliers: • http://aquaticeco.com/ • http://www.tecinfo.com/~aqcenter/ • Eagar, Inc. 1-800-423-6249