Barramundi

 Barramundi (//Lates calcarifer//)



The barramundi is one of the largest of Australia's inland fish. This species belongs to the giant perch family. Barramundi can live in both fresh and salt water. They are found in tropical areas throughout the South-East Asia region, including northern Australia. Barramundi have white flesh, which is highly regarded throughout the world. 
 * [|Identifying features]
 * [|Habitat]
 * [|Optimum range of water quality]
 * [|Feed]

Barramundi can grow to 150 cm and 60 kg. They can be identified by the following features: [|back]
 * grey-green to golden brown colouring
 * rounded caudal fin (tail)
 * slightly concave forehead
 * two dorsal fins - the first has 8 - 9 spines, and the second is soft and flexible
 * an anal fin with 3 spines
 * jaw that extends to beyond the end of the eye.

[|back]
 * Barramundi live in both fresh and salt water. Barramundi larvae and young barramundi (juveniles) are found in waters of very low salinity or salt. This water is usually swamp water near estuaries. Older juveniles are found in the upper parts of rivers. Full-grown barramundi live in estuaries and nearby coastal areas; they can also be found in the lower part of a river. Barramundi are found throughout the northern part of Australia. || [[image:http://www.westone.wa.gov.au/toolboxes/aquaculture/images/stock/barramundi_map.gif width="150" height="130" caption="Map of Australia showing barramundi habitat"]] ||


 * || **Water quality factor** || **Optimum range** ||
 * Temperature || 26 - 30°C ||
 * pH || 7.5 - 8.5 ||
 * Dissolved oxygen || More than 4 mg/l ||
 * Turbidity || 30 cm ||
 * Alkalinity || More than 5 mg/l ||
 * Hardness || 50 - 200 mg/l ||
 * Ammonia || Less than 0.1 mg/l ||
 * Nitrite || Less than 0.1 mg/l ||
 * Salinity || 0 - 36 ppt ||  ||

[|back]

The barramundi ( //Lates calcarifer//) is a large predatory fish found in tropical regions of Australia. It has a natural distribution extending from the Ashburton River in Western Australia (WA), throughout the Northern Territory (NT), to the Maryborough River in Queensland (QLD). The barramundi is a greenish grey on the dorsal surface, changing to silver on the sides. The mouth is large and the eye glows red at night under flashlight. The species is portrayed widely in northern Australian Aboriginal mythology where it has been used historically as a primary food item. It is also commonly regarded as the premium recreational sportfish in northern Australia. The barramundi's attributes as an aquaculture species have more recently been realised.
 * **Fish Size (mm)** || **Fish Size (g)** || **Pellet Size** || **Feed Frequency (times/day)** ||
 * 20 - 25 || 0.13 || 1 mm Crumble || 4 ||
 * 25 - 30 || 0.222 || 1 mm Crumble || 4 ||
 * 30 - 35 || 0.58 || 1 mm Pellet || 3 ||
 * 35 - 40 || 0.8 || 1.5 mm Pellet || 3 ||
 * 40 - 45 || 1.28 || 2 mm Pellet || 3 ||
 * 50 - 55 || 1.65 || 3 mm Pellet || 3 ||
 * 55 - 60 || 2.12 || 4 mm Pellet || 3 ||


 * WATER QUALITY**

 The osmoregulatory abilities of Barramundi allow their culture in both freshwater and saltwater environments and they have the ability to quickly acclimatize to changes in salinity. They are also very hardy and generally do well in highly intensive situations. However, in order to maximise growth, tank conditions should remain as close as possible to optimum levels. The farmer should monitor water quality and fish health closely and take action immediately where required. In the initial stages, Barramundi should only be stocked at a rate that the system can handle. This can be increased, as the farmer becomes more experienced. Dissolved oxygen levels should be between 4-9ppm, however levels as low as 3ppm will be tolerated for very short periods. Free ammonia levels should not exceed 1mg/L and temperatures should be maintained at 26-28°C. Barramundi will tolerate exposure to levels slightly outside of the ranges listed above but will result in slowed growth rates and stress. Prolonged exposure to sub-optimum conditions will result in increased incidence of disease and death.


 * Diseases and parasites **

 Barramundi are naturally susceptible to most bacterial, fungal and parasitic infections particularly at times of stress. This is as with most other aquaculture species and can usually be avoided by appropriately quarantining new stock before release into culture tanks, maintaining water quality and a stress free environment and regular disease monitoring of stock. In the event of disease outbreak, stock can sometimes be effectively treated by salt or freshwater bathes, or via veterinarian prescribed treatments. Of particular concern to NSW DPI are the aforementioned BEV and the possible introduction of this virus to NSW. To address these concerns NSW DPI have included provision within the Barramundi Farming Policy for the sterilization of all effluent to be removed, as well as a specific import protocol for the importation of barramundi fingerlings from out-of-state. This includes the testing of fingerlings for presence of the BEV as well as other diseases and virus. This policy will not only reduce the chance of translocation of the virus into NSW, but also ensures that the farmer has a guarantee of healthy good quality seedstock.


 * Growth and reproduction **

 Due to the potential for the spread of BNNV to native NSW fish, culture of barramundi in NSW has been restricted to intensive recirculation tanks only. Most of the research done in northern Australia has focused on pond culture, however, much of this technology is being transferred to tank culture systems, particularly in the southern states and the cooler regions of Queensland. Tank culture technology has made it possible for most mainland states to produce barramundi. Stocking rates in tank systems vary, depending on the capacity of the system and the intensity of the operation. Many producers work on a stocking rate of around 30-40kg/m3, however more advanced systems may be able to increase the stocking rate, depending on the experience of the farmer and husbandry practices used. The optimum temperature for barramundi culture is 28°C, with acceptable growth rates between 26-30°C. Temperatures below this range will result in decreased metabolism and growth. Barramundi generally stop feeding at temperatures below 20°C. To maintain acceptable growing temperature conditions, some existing farms rely on the use of warm subterranean bore water and climate controlled or insulated sheds. Expensive alternatives include the heating of individual tanks with electric submerged heaters. At optimum temperatures, barramundi can be raised to market size (500g) between 6-12 months. Due to the carnivorous nature of barramundi, a high protein diet is required for efficient growth. Commercial diets are readily available from a number of feed manufacturers and are generally produced in a floating or sinking pellet. Food conversion ratios (FCRs) for barramundi should be in the range of 1.5-2:1 (kg of food:kg of weight growth), however lower FCR's have been reported by some industry members. The very nature of intensive recirculation tank farming means that water requirements are much lower than that for pond culture. However, the high stocking densities, reliance on powered biofilters and use of high protein feeds can lead to water quality deterioration if left unchecked, therefore greater supervision in required. Tanks should be cleaned and biofilters back-washed regularly to avoid blockage. Backup power generation should also be supplied.


** Behaviour **

 Barramundi are gregarious (readily school) and adapt easily to high stocking densities. However, by nature they are also highly cannibalistic and will eat tank mates up to two thirds of their own size. To avoid problems of cannibalism, stock should be graded at least once a week and separated into appropriate size classes. This will also reduce size variation between groups (assist in marketing), while reducing expensive mortality through cannibalism.