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AC006 Understanding Water Requirements of Fish

Aquaculture Library

Water is vital!

• Fish need water to• Breathe• Eat• Grow• Reproduce

• The choice of production system is often dictated by the quantity and quality of water available.

Important water qualities include …

• Sufficient quantity• Free of chemicals

or environmentalpollutants

• Water supply that will not be affected by future development or industry

Water sources from best to worst …

• Springs• Wells• Rivers, streams or lakes• Surface run-off• Groundwater• Municipal

BEST

WORST

Springs and wells -- the two most common sources:

• Advantages:• Both maintain steady temperature• Less subject to contamination than surface

water supplies

• Disadvantages:• Quantity may be a problem.• Water requires pumping• Dissolved gases (carbon dioxide, nitrogen,

methane, hydrogen sulfide) may harm your crop

Rivers, streams and lakes as water sources …

• Advantage:• Inexpensive

• Disadvantages:• Continuous supply may not be dependable• Droughts, floods, seasonal fluctuations• Contaminants (pesticides, organic matter,

sediments, metals, wild fish, parasites, insects) may be a problem.

Surface or runoff water as your water supply …

• Advantage:• Inexpensive

• Disadvantages:• Contaminants• Subject to seasonal fluctuations.• Requires considerable land -- five to seven

acres of watershed per surface acre of water

• Unlikely to be suitable for commercial production, but may work for a fee-fishing operation

Groundwater water source …

• Advantage:• Inexpensive

• Disadvantages:• Ponds are hard to drain; harvesting difficult• Same problems as surface or run-off sources• Wetlands may require environmental studies• May require permits

Municipal water supplies …

• Advantage:• High quality water

• Disadvantages:• Quite expensive• May contain chlorine or

other treatment chemicals

Testing for water quality …

• Simple and reasonable in cost• Kits range from inexpensive aquarium

type to battery-operated meters• Kits can test for various

substances:• Dissolved oxygen• Carbon dioxide• Nitrate

• Nitrateammonia

• Hardness• Alkalinity

Some tests are expensive:

• Pesticides and heavy metals testsare high in cost.

• Most samples are screened only forthe 3 most common contaminants:• DDT• Lead• Mercury• Even 1 part per billion (ppb)

may be a problem

Water quality must be continually monitored …

• Fish will die if dissolved oxygen is too low.• Excess waste buildup damages gills and leads

to diseases.• Cooperative Extension

Service may offeradvice and workshopson water testing.

A final caution:

• If you put off buying and learning about test equipment you may find a whole pond of sick or dying fish.

• Taking time to check oxygen, ammonia, nitrate and other water quality factors on a regular basis pays off in fewer fish kills and disease problems.

This presentation was produced and is copyrighted by Stewart- Peterson®, Inc. 2003-2005. Permission is granted for use by active AgEdNet.com® subscribers. All other use is prohibited.

STEWART-PETERSON and AGEDNET.COM are registered trademarks of Stewart-Peterson, Inc.

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