Food for carp
One should distinguish between foods used for fish production in ponds and in the so-called industrial environments (fish tanks, pools) where fish are kept at the super-dense plantings (up to 250 ind./m). In ponds, even at high planting densities (over 5 thousand ind./ha, or 0.5 individuals/ m2), the fish has the ability to consume natural food that is a source of biologically active substances — vitamins, minerals, and valuable protein. Therefore, pond feeds does not impose such stringent requirements on the balance and value of diets.
Quality set of feeds with a high enough level of protein, vitamins and other components can be improved by the fish due to consumption of biologically valuable natural food. At stocking density of fingerling carp in ponds 5 thousand ind./ha the proportion of natural food in the content of their intestines is not less than 10 — 15%, with a density of 30 — 35 thousand ind./ha, it is further reduced, but is still 5 — 7% of the daily diet on average during the season.
A different picture is observed when extremely high densities of fish landing in the industrial conditions of ponds and pools. The proportion of natural food in the diets of fish is practically zero. Consequently, feeds used in these conditions must be complete, i.e. contain all necessary for the growth and development of fish substances, as well as balanced,that is, to contain them in such quantities and proportions to match the dietary needs of fish. So the food used for industrial fishery, contain more protein, fat, include premixes, enzyme preparations, antioxidants. Accordingly, they are more expensive. The fish grown on such feed, has a higher cost than pond.
In table. 1 shows the recipes of feed for common carp grown in ponds. They should contain crude protein: for young of the year — at least 26%, for commodity fish — not less than 23%; fat — not less than respectively 4% and 3.5%, calcium — 1,2% and 0,7%, phosphor 1,0% and 0,8%; fiber intake should be no more than 9% and 10% respectively. All these requirements satisfy the feed formulation shown in table. 1. They allow to achieve good results for densities of 50 — 100 thousand young of the year per 1 ha and year old commercial 2 — 5 thousand ind./ha. With fodder VBS-RJ is more effective at high densities of fingerling and feed 111-1 and PC-BP is a year old.