This Primefact is a guide to stocking fish for angling and domestic consumption on private property only.
Commercial fish farming (aquaculture) is a specialised venture needing thorough investigation of the technology and economics, and requires a permit from NSW DPI (which has literature on fish and crayfish farming).
Stocking of fish into public waters (including creeks, rivers and impoundments) requires a special NSW DPI permit.
The past 20 years has seen a growing demand for freshwater fishes to stock farm dams. Several million fish have been sold to farmers throughout New South Wales.
However, the stocked fish have had various fates, with reports varying from virtually 100% survival and growth of 1 kg per year to anecdotal reports like ‘I didn’t see a sign of the fish ever again’.
To improve these variable results, during the late 1970s NSW DPI examined ways of increasing fish production in farm dams. The research showed that production depends on many factors, including food, predator control, water quality, water depth and climate that are often beyond the landowner’s control. Nevertheless, there are ways to enhance production, and have fish on the table sooner.
This document outlines a range of issues you need to consider before attempting to stock fish and to maximise their survival after stocking, including:
- the dam (location, size, and suitability);
- water quality;
- choice of species;
- stocking rates;
- fish stocking, survival, growth and feeding;
- potential problems and how to deal with them.
The dam Size:
The dam should have a surface area of at least 0.05 ha (500 m2 ), preferably more.
Stock access:
Ideally, livestock should be excluded from dams stocked with fish, as they can damage dam walls and muddy the water. The best approach is to completely fence the dam, and provide an external trough with pumped or gravity fed water, although this may not always be practical.
An alternative is to partially fence the dam, and restrict stock access to a narrow entry. Planting the fenced area with trees has several benefits. Planting can improve the dam’s appearance and stabilise its banks, whilst decaying leaves provide nutrients to start the food chain, and falling insects are preyed upon by fish.
Do not grow trees or shrubs on the embankment or spillway as they can disturb the dam structure.
Location:
It is illegal to permit fish to escape from a dam. Dams that are likely to flood (as in a gully) should not be stocked, as it can be hard to prevent fish escaping. As well as reducing production in the dam, escaped fish can cause major problems in local river systems, especially if they are not native to the local area.
NSW DPI recommends that only dams above the 1 in 100 year flood level on the eastern drainage and dams not inundated by a 1 in 100 year flood on the western drainage should be used for fish stocking, to ensure that fish do not escape to waterways.
Ease of maintenance:
Consider installing a pipe and gate-valve in a new dam, so that it may be drained from the bottom.
This allows bad water to be drained easily, and complete drainage helps in dam maintenance. (The site must have some slope.) Drained water should not enter adjacent waterways.
Preparing the dam:
Consider removing unwanted plants and fish from an existing dam before restocking. New dams should be filled and ‘aged’ for at least three months before stocking. This gives the food chain time to develop, and can be assisted by adding locally native water plants, shrimps and yabbies from other dams or other sources.
Note. A Department of Natural Resources permit is needed to build a dam on a watercourse. A NSW DPI permit may be required to collect organisms to put in farm dams. Some species are illegal to stock in your dam – check with NSW DPI.
Water quality:
Comprehensive water tests are expensive and are generally not needed for farm dams. Most surface and bore water suitable for irrigation or stock is acceptable for fish. A small test stocking will quickly show whether the water is suitable.
Muddy water may not harm native fishes directly but it can lower food production by preventing light penetration. On the other hand, some turbidity can help reduce predation by making the fish hard to detect by predators.
Choice of species:
Species to avoid:
Some fish species (which are listed as noxious in NSW) are illegal to stock into farm dams. For the latest list of noxious fish, visit the NSW DPI Fisheries website (www.dpi.nsw.gov.au/fisheries).
Many exotic species, even if they are not illegal, are undesirable, either because of their effects on the dam or because of their risk to the natural environment if they escape. More information on some of these undesirable species can be found later under ‘Potential problems’. There are good reasons for stocking fish that occur naturally in your area.
- Local fish are well adapted to the environmental conditions, and likely to survive well in your dam, provided they are not predated.
- Suitable local fish are frequently available from the nearest hatchery.
- If exotic fish are stocked and escape into the wild, they can become serious pests which compete with native species and cause environmental damage. This can apply even to stocking native fish from a different part of NSW or Australia.
Also take care to buy only native water plants for your dam. Many exotic plants can not only choke your dam but may end up spreading and blanketing local rivers.
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