Weaning marine finfish larvae from live food to dry microdiet continues to be a major challenge.
In most research and commercial hatcheries, the feeding of microdiet is usually done manually.
Feeding several times a day demands high labor requirements and administering large amounts of food infrequently can cause fouling issues. A high proportion of microdiet remains uneaten and settles on the bottom of the tank. This leads to bacterial proliferation and reduced dissolved oxygen levels, which increases larval stress and the risk of infection.
An automatic feeding system developed by the Department of Fisheries aims to resolve these problems.
The feeding system
The basic feeding system consists of a central touch screen controller and 24 Automated Microdiet Dispenser (AMD) units. Stand-alone electronic controls and low profile compact feeding units allow easy integration into existing infrastructure.
The AMD system can reduce costly labour requirements and facilitate feeding outside of working hours. The AMD system administers small amounts of microdiet that maximise the availability to larvae by increasing the frequency of encounters. This more closely resembles live feed availability and leads to a healthier environment and more efficient weaning by allowing the larvae to consume a greater proportion of microdiet.
The AMD system presents a wide range of versatile feeding regimes for larvae and juvenile fish. The operator can easily customise for specific feeding requirements on a daily basis through a user-friendly touchpad interface. Alternatively, a series of feeding regimes can be pre-programmed to cater for changing larvae requirements, which can be used repeatedly for successive larval production runs.
The controller operates 24 AMD units or more (optional expandable unit), either individually or as a group of identical feeders. Each AMD unit periodically administers an operator-determined number of microdiet doses during one to four feeding periods. This allows the culturist to provide microdiet evenly across the whole day, or provide periods of relatively high and low intensity feeding that cater for diurnal larvae requirements. A more constant availability of microdiet is provided when the larvae need it.
Other applications such as dissolved oxygen monitoring, lighting and pumping can be integrated into the same control mechanism in order to ensure concurrent operation of system components.
The Automatic Microdiet Dispenser (AMD™)
The AMD is designed to periodically administer a small amount of microdiet to larvae rearing tanks. The AMD can cope with microdiet particle sizes from 100 µ to 2mm. As little 100mg ± 2 %, depending on the microdiet, is released without the need to weigh the diet each time.
The AMD mechanism is based on two ABS slotted plates located below a food hopper. A stationary base plate is situated below an oscillating feeder plate. While the feeder is inactive, the bars of the base plate block the slots of the feeder plate. During activation a solenoid is energised to draw the feeder plate across the base plate so that the slots momentarily line up and allow microdiet to flow. An air manifold constantly jets beneath the plates in order to scatter the microdiet across the water surface within a target area.
Complete solution for hatchery feeding
A new controller has been developed to provide a complete solution for both live feeds and algae, as well as weaning diets.
The controller is capable of operating 24 outlets, independently or in groups, with any combination of AMD feeders and peristaltic pumps. The peristaltic pumps can operate at different time intervals and at different pumping rates to constantly or periodically supply algae, Artemia and rotifers.
For more information contact Sagiv Kolkovski firstname.lastname@example.org.
Feeder Aliquote Tables 2012 24v.pdf