WATER IN AQUACULTURE SYSTEMS To a great extent

WATER IN AQUACULTURE SYSTEMS To a great extent water quality determines the success or failure of a fish farming operation

WATER IN AQUACULTURE SYSTEMS Fish perform all bodily functions in water • • • Eat Breathe Take in and lose salts

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

Water Balance in Saltwater Fish Water Drinks sea water Ammonia Small quantities of concentrated urine

Water Resources • Water quality • Water quantity • Water sources Inadequate water quality causes more losses than any other problem!

WATER IN AQUACULTURE SYSTEMS Physical Temperature • • Chemical (“No effect” limits)

WATER IN AQUACULTURE SYSTEMS Physical Characteristics of Water • • “Universal solvent” –

Dissolved Oxygen • Importance – highest cause of mortality • Solubility – variables • • Safe levels – > 5 mg/l

Projected Dissolved Oxygen Levels for Ponds 7 Measured values 6 5 mg/l 4 Projected values 3 2 1 0 5 pm 10 pm 5 am

Uniform dissolved O in pond 2

High dissolved oxygen (warm) Low dissolved oxygen (cool) Decomposing materials

Turnover Low dissolved oxygen - possible fish kill

Relationships

Percent of Total Ammonia in the Un-Ionized Form at Various Temperatures and p. H Percent Ammonia Temperature (F) (p. H) 7. 0 8. 0 50 0. 19 1. 83 15. 7 68 0. 40 3. 82 28. 4 86 0. 80 7. 46 44. 6 9. 0

Nitrification NH 3 1½ O 2 nitrosomonas NO 2 - 1½ O 2 nitrobacter NO 3 - • Requires 3 moles oxygen to convert one mole of ammonia to nitrate •

Dissolved Gasses • Problem gasses – Nitrogen (primarily) dorsal view • • Problem sources – Wells and Springs – – Popeye/exophthalmia leaky pipe

WATER IN AQUACULTURE SYSTEMS Water quantity parameters • Requirements are based on temperaturedependent and size-dependent standard metabolic rates for fish •

WATER IN AQUACULTURE SYSTEMS Water quantity parameters Suggested replacement times Linear • Noncirculating – • Circulating Suggested water velocity rates • Noncirculating – • Circulating -

WATER IN AQUACULTURE SYSTEMS Water quantity parameters Flow measuring techniques Flow meters • • Pond filling time – not very accurate

WATER IN AQUACULTURE SYSTEMS Water quantity parameters Weir gauges • Sharp-crested – if outfall consists of dam boards • V-notch • Trapezoidal • •

WATER IN AQUACULTURE SYSTEMS Pre-Use treatment Sediment removal • Settling basin/pond – • Filtration – Gas stabilization (O 2 and/or N 2) • Slatted inflow boards • •

WATER IN AQUACULTURE SYSTEMS Pre-Use treatment Sterilization • Ultraviolet – • • Chlorination-de-chlorination – • Temperature control • Heating • Chilling

WATER IN AQUACULTURE SYSTEMS Water utilization • Open water systems • Flow-through -Water enters pond or series of ponds and exits with/without treatment - -

Water Sources • • • Rivers, lakes and streams Surface

Springs • Advantages – – few or no predators – no pathogens • Disadvantages –

Wells • Types – – • Advantages – no predators – no pathogens • Disadvantages – – low O 2

Rivers, Lakes and Streams • Advantages – large volumes – inexpensive • Disadvantages – – excessive nutrients

Surface • Advantages – inexpensive • Disadvantages – contaminates – – 5 -7 acre watershed per surface acre of water

Groundwater • Advantages – • Disadvantages – hard to drain • • removal of fish

Municipal • Advantages – – no predators – • Disadvantages – disinfectants • • chloramines –

Water Quantity • • Ponds Raceways Cages Recirculating aquaculture systems

Ponds • Minimum requirement – 13 gal/min or 50 L/min per acre • Rational – – to replace evaporation –

Raceways • Minimum requirement – 500 gal/min. or 1900 L/min • Rational – –

Recirculating Aquaculture Systems • Minimum requirement – varies depending on size of system – • Rational – needed to backflush filters during harvesting – –

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