Abstract: The present disclosure provides systems and methods for recycling gas in a reactor. An example of gas-recycling system comprises: a housing, a gas conduit, and a powered propeller. The housing encloses a gas space and a liquid space, wherein the gas space is configured to collect gas within a reactor. The powered propeller comprises a shaft having an upper end and a lower end; and a plurality of radial blades connected to the lower end of the shaft. Upon rotation of the powered propeller, the powered propeller is configured to: generate a suction to cause the collected gas to flow from the gas space to the liquid space through the conduit; cause fluid of the reactor to flow in a direction from the upper end of the shaft to the lower end of the shaft; and mix the liquid and the collected gas proximate the powered propeller.

Abstract: Extruded, formulated, complete feed for aquatic species, said formulated, complete feed comprising: at least one non-hydrolysed protein source; at least one fat source; fibers inherent in at least one raw material; optionally at least one carbohydrate containing source; a vitamin additive; a mineral additive; water; a binder comprising at least partly an edible, starch containing, tuberous-originating thickening agent; a hydrolysed plant protein source; and a plasticizer, and said formulated, complete feed comprises a moisture content from about 12.5% to about 25% (w/w) of the complete feed. A method for production of the feed is disclosed as well.