Culture environment for eels

Eels can be grown in both pond and recirculating tank systems. They have a high stocking density tolerance, which means a large number can be grown in a relatively small area (see 'Stocking density' below).

Eel farming requires access to large volumes of water, as regular water exchange is required due to the high stocking densities and messy feeding behaviour of the eels,

Pond systems

For pond-based aquaculture, research has determined the best site is one with constant water supply, and which is not susceptible to flooding. Bore water is suitable as long as it is free from pathogens and chemical residues and has a pH of 7.0–8.0. Highly acid water is not acceptable. A gently sloping site will make it easier to fill and drain ponds.

Tank systems

For intensive tank-based eel aquaculture, site selection criteria such as climate and soil quality are less restrictive, although a source of good-quality water is still essential.

Water quality

Eels require large amounts of oxygen if they are to remain active and grow at an optimal rate. Aeration can be supplied using paddlewheels or aspirators. Blooms of phytoplanktonic algae are encouraged as they produce oxygen and shield the eels from direct sunlight.

Regular water exchange is necessary to maintain water quality due to the often high stocking densities. The pH, dissolved oxygen, temperature, total nitrogen and nitrite levels need to be checked regularly. Ideally, the water should have a pH of around 7, dissolved oxygen levels no lower than 3 parts per million and free ammonia levels of less than 0.2mg per litre. If water quality deteriorates, corrective measures need to be applied quickly to ensure minimal stock loss.

Stocking density

Stocking rates in tank systems and pond systems vary, depending on the capacity of the system and the intensity of the operation. As a general rule, biomass in ponds should not exceed 10t per hectare. In tanks it should not exceed 50kg per cubic metre.

Temperature

Eels grow rapidly in a tropical climate, preferring temperatures between 23^oC and 28^oC. In ideal conditions they grow to marketable size (150–200g) in 12–18 months, although growth rate can be extremely variable.

Also consider...

• Find out how to get started in aquaculture.
• You will need to discuss technical and licensing aspects of any proposed aquaculture venture with staff from Fisheries Queensland and the Department of Environment and Science before proceeding with site selection, design and, where applicable, land purchase.
• Find out how to prevent, identify and manage disease in aquaculture farms.
• Download the latest report to farmers for aquaculture industry statistics and production data.