Shrimp differ in a lot to other farmed species:

Shrimp are benthic. They only use the bottom of a pond.
Shrimp must find the feed by chemical attraction (olfactory sensors). Feeds should leach substances (often useful nutrients) to attract shrimp to the feed.
Typically, shrimp feed pellets will stay in the water for 15 - 60 minutes before the shrimp consumes them. But they can lie in water for several hours before consumption and should remain water-stable during this time. During this time, feed pellets swell by taking up water and water-soluble nutrients leach out of the pellets. These nutrients are a loss. In semi-intensive farming, shrimp are typically fed 3-4 times/day. This worsens the problem enormously.
Shrimp are external masticators, meaning that they chew their feed outside their mouth. They are selective feeders, nibbling on pellets and only consume more feed when palatability is OK: When shrimp start consuming feed, they will not ingest the feed at once. They will nibble on it, select the palatable pieces and throw away whatever they don’t like. The uneaten parts are left and will be digested on the pond bottom by bacteria.
Shrimps are poor digesters. Their digesting system is rudimentary. A lot of nutrients pass their system without being assimilated. For example, the protein efficiency of shrimp is only 15-20 %.
In nature, shrimps will consume a lot of pre-digested feed, like rotten fish and detritus. Whatever is not assimilated goes back to nature and is recycled. In ponds however, as density of production increased, these excess nutrients became pollutants, using oxygen and degrading into ammonia, hydrogen sulphide and methane, all toxic to shrimp. To get rid of those pollutants, water is exchanged and the pollutants are flushed out of the system. This way, the chance of recirculating them is lost and the feed will never be utilised at this maximum. This is the main reason why feed conversions in shrimp culture are horribly high and don’t show any progress during the last couple of years.
Shrimps can consume detritus actively or passively. Soluble nutrients will dissolve in the pond water and feed the natural bloom of the pond: phytoplankton, which in turn will feed zooplankton. The shrimp will ingest some of this plankton again. This is what we call natural production of the pond.
Crustaceans have some unique nutritional requirements such as phospholipids, cholesterol, Phosphate to Calcium ratio. Knowledge of shrimp nutrition has increased during the years, but application in business has been difficult. Semi-intensive farming is not the system that will maximise shrimp efficiency and different shrimp feed qualities have not show substantial differences in the production. Hence, shrimp producers tend to choose the cheapest feed.

Shrimp Feed Premix