Feeding can be done by hand, or by automatic feeders or feeding systems. The time used for feeding can be considerable for large farms with intensive production, and can justify the investment in a system for automatic feeding. For instance, the daily requirement of feed for a rainbow trout farm with a standing biomass of 100 t of 100 g fish is at least 3500 kg per day with a water temperature of 16°C.
For intensive fry production, several species require an almost continuous supply of food, especially in the first feeding stage. This requires a tremendous amount of work, and is therefore normally done by automatic feeders. Feeding systems are of most interest for intensive aquaculture systems because of the importance of getting as much feed as possible into the fish.
How easy it is to automate the feeding depends on the feed type used. Dry, extruded or pelleted feed is quite easy to deal with: the particles are fixed and hard. Wet feed or moist feed is rather more difficult to feed automatically. To find good systems for distribution of dense particles is also difficult. Wet feed may be fed through pump systems, but here it is difficult to obviate the possibilities for over feeding; possible environmental impacts are also much higher with this type of feed.
The size and shape of the dry particles will also influence the feasibility of feeding automatically: small feed particles, for example for marine or freshwater fry, might be a problem. If the feed is like meal, it might be difficult to get it through the feed dispenser; it might clog inside the hopper, and the sliding angle is very high.